An Introduction to Starting a Biobank

The purpose of a biobank is to process, organize, and maintain various types of biospecimens that are to be utilized for both clinical and research-based services. There are different types of biobanks, so the goals of the biobank should be delineated at the outset of forming a biobank. The startup of a biobank benefits from accreditation and stringent adherence to standards of practice. Fundamental to these practices is the protection of privacy and informed consent. A budget must be developed, and sources of funding should be obtained to properly equip the designated space and personnel. The appropriate space for freezers and for biospecimen processing should be identified. Information technology is also a critical part of the biobank and effort should be expended to ensure that this aspect is effective and secure. Given the ethical concerns surrounding biospecimens, engagement with the public is also highly valuable.

Orientation and Training of New Biobank Personnel

The personnel who operate a biomedical biobank should function as a unit to efficiently manage the numerous types of biospecimens that are to be utilized for both clinical and research purposes. Therefore, new staff must be appropriately trained before becoming fully integrated into the work environment. This chapter focuses on several key aspects to this training that should be completed by all personnel. This first step is an orientation where the new trainee is provided with the priorities and expectations of the biobank. The next and perhaps most important step is training on the various safety precautions. The trainee should learn how to protect patient privacy if human biospecimens are involved. They should gain a basic understanding of different types of biospecimens and their vulnerabilities to suboptimal storage conditions. The trainee must learn the various aspects of the day to day work which encompasses the methods and equipment needed for procuring, labeling, handling, tracking, storing, disbursing, and shipping biospecimens. They should become familiar with aspects of quality assurance.

Early experience with formalin-fixed paraffin-embedded (FFPE) based commercial clinical genomic profiling of gliomas-robust and informative with caveats

BACKGROUND

Commercial targeted genomic profiling with next generation sequencing using formalin-fixed paraffin embedded (FFPE) tissue has recently entered into clinical use for diagnosis and for the guiding of therapy. However, there is limited independent data regarding the accuracy or robustness of commercial genomic profiling in gliomas.

METHODS

As part of patient care, FFPE samples of gliomas from 71 patients were submitted for targeted genomic profiling to one commonly used commercial vendor, Foundation Medicine. Genomic alterations were determined for the following grades or groups of gliomas; Grade I/II, Grade III, primary glioblastomas (GBMs), recurrent primary GBMs, and secondary GBMs. In addition, FFPE samples from the same patients were independently assessed with conventional methods such as immunohistochemistry (IHC), Quantitative real-time PCR (qRT-PCR), or Fluorescence in situ hybridization (FISH) for three genetic alterations: IDH1 mutations, EGFR amplification, and EGFRvIII expression.

RESULTS

A total of 100 altered genes were detected by the aforementioned targeted genomic profiling assay. The number of different genomic alterations was significantly different between the five groups of gliomas and consistent with the literature. CDKN2A/B, TP53, and TERT were the most common genomic alterations seen in primary GBMs, whereas IDH1, TP53, and PIK3CA were the most common in secondary GBMs. Targeted genomic profiling demonstrated 92.3%-100% concordance with conventional methods. The targeted genomic profiling report provided an average of 5.5 drugs, and listed an average of 8.4 clinical trials for the 71 glioma patients studied but only a third of the trials were appropriate for glioma patients.

CONCLUSIONS

In this limited comparison study, this commercial next generation sequencing based-targeted genomic profiling showed a high concordance rate with conventional methods for the 3 genetic alterations and identified mutations expected for the type of glioma. While it may not be feasible to exhaustively independently validate a commercial genomic profiling assay, examination of a few markers provides some reassurance of its robustness. While potential targeted drugs are recommended based on genetic alterations, to date most targeted therapies have failed in glioblasomas so the usefulness of such recommendations will increase with development of novel and efficacious drugs.

MASH1/Ascl1a leads to GAP43 expression and axon regeneration in the adult CNS

Unlike CNS neurons in adult mammals, neurons in fish and embryonic mammals can regenerate their axons after injury. These divergent regenerative responses are in part mediated by the growth-associated expression of select transcription factors. The basic helix-loop-helix (bHLH) transcription factor, MASH1/Ascl1a, is transiently expressed during the development of many neuronal subtypes and regulates the expression of genes that mediate cell fate determination and differentiation. In the adult zebrafish (Danio rerio), Ascl1a is also transiently expressed in retinal ganglion cells (RGCs) that regenerate axons after optic nerve crush. Utilizing transgenic zebrafish with a 3.6 kb GAP43 promoter that drives expression of an enhanced green fluorescent protein (EGFP), we observed that knock-down of Ascl1a expression reduces both regenerative gap43 gene expression and axonal growth after injury compared to controls. In mammals, the development of noradrenergic brainstem neurons requires MASH1 expression. In contrast to zebrafish RGCs, however, MASH1 is not expressed in the mammalian brainstem after spinal cord injury (SCI). Therefore, we utilized adeno-associated viral (AAV) vectors to overexpress MASH1 in four month old rat (Rattus norvegicus) brainstem neurons in an attempt to promote axon regeneration after SCI. We discovered that after complete transection of the thoracic spinal cord and implantation of a Schwann cell bridge, animals that express MASH1 exhibit increased noradrenergic axon regeneration and improvement in hindlimb joint movements compared to controls. Together these data demonstrate that MASH1/Ascl1a is a fundamental regulator of axonal growth across vertebrates and can induce modifications to the intrinsic state of neurons to promote functional regeneration in response to CNS injury.

Permissive Schwann cell graft/spinal cord interfaces for axon regeneration

The transplantation of autologous Schwann cells (SCs) to repair the injured spinal cord is currently being evaluated in a clinical trial. In support, this study determined properties of spinal cord/SC bridge interfaces that enabled regenerated brainstem axons to cross them, possibly leading to improvement in rat hindlimb movement. Fluid bridges of SCs and Matrigel were placed in complete spinal cord transections. Compared to pregelled bridges of SCs and Matrigel, they improved regeneration of brainstem axons across the rostral interface. The regenerating brainstem axons formed synaptophysin(+) bouton-like terminals and contacted MAP2A(+) dendrites at the caudal interface. Brainstem axon regeneration was directly associated with glial fibrillary acidic protein (GFAP(+)) astrocyte processes that elongated into the SC bridge. Electron microscopy revealed that axons, SCs, and astrocytes were enclosed together within tunnels bounded by a continuous basal lamina. Neuroglycan (NG2) expression was associated with these tunnels. One week after injury, the GFAP(+) processes coexpressed nestin and brain lipid-binding protein, and the tips of GFAP(+)/NG2(+) processes extended into the bridges together with the regenerating brainstem axons. Both brainstem axon regeneration and number of GFAP(+) processes in the bridges correlated with improvement in hindlimb locomotion. Following SCI, astrocytes may enter a reactive state that prohibits axon regeneration. Elongation of astrocyte processes into SC bridges, however, and formation of NG2(+) tunnels enable brainstem axon regeneration and improvement in function. It is important for spinal cord repair to define conditions that favor elongation of astrocytes into lesions/transplants.

Immunohistochemical analysis of the monoclonal antibody 4B5 in breast tissue expressing human epidermal growth factor receptor 4 (HER4)

AIMS

A recent study examining the specificity of human epidermal growth factor receptor (HER) 2 pharmacodiagnostic antibodies demonstrated that CB11 and 4B5 stain both HER2-transfected and HER4-transfected cell lines. However, there has been no evidence showing that 4B5 has affinity for HER4 in clinically obtained tissues, and, if so, whether this has any impact on the assessment of HER2. We therefore sought to determine the expression of membrane-bound HER4 in clinical breast carcinomas, and evaluate its impact on the clinical utility of 4B5 in determining HER2 status.

METHODS AND RESULTS

Breast carcinomas were assessed by immunohistochemistry (IHC) for membrane-bound HER4 using anti-HER4 clone E200. HER2 expression in these cases was then assessed using anti-HER2 clone 4B5, and a reference clone, SP3. In all 117 membrane HER4-positive cases (out of 241), 4B5 scored equal to or less than the reference anti-HER2 clone SP3. Eighteen cases were positive for membrane-bound HER4 by E200 and negative by 4B5, including a membrane HER4 level 3+ case.

CONCLUSIONS

No cross-reactivity of 4B5 with membrane-bound HER4 was identified in the clinical IHC analysis of formalin-fixed paraffin-embedded breast carcinoma cases as evidenced by the HER4 antibody clone E200.

Immunohistochemical analysis of pathway HER2 4B5 performance in breast carcinoma expressing HER4

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Background: The ability of pharmacodiagnostic antibodies to specifically detect their target antigen is essential to their performance. Non-clinical protein based models for specificity of two human epidermal growth factor 2 (HER2) pharmacodiagnostic antibodies, Oracle CB11 and PATHWAY HER2 4B5 (4B5) (Ventana Medical Systems Inc., Tucson, AZ, USA), have been reported to demonstrate affinity to both HER2 and HER4. To date there has been no evidence showing that affinity of 4B5 for HER4 impacts the IHC clinical HER2 assay. We therefore sought to investigate whether there exists any risk of the 4B5 antibody detecting HER4-positive but HER2-negative cases as falsely positive due to a hypothetical cross reactivity to HER4. Methods: A HER4 IHC assay was developed by screening ten HER4 antibodies for specificity by staining FFPE blocks of recombinant HEK-293 cells expressing HER1, HER2, HER3 and HER4. Specific HER4 antibodies were then evaluated in breast carcinoma to identify a clone that provided distinct membrane staining in tumour cells. This pattern was used as a reference in order to detect any potential interference of HER4 detection in determining the HER2 score. The HER4 antibody E200 (Epitomics) was selected and used to evaluate a cohort of breast carcinoma cases. The HER2 expression in these cases was then assessed using anti-HER2 clone PATHWAY HER2 4B5 and a HER2 reference antibody, clone SP3 (Spring Bioscience). Results: 117 out of 241 (48%) breast tissue cases evaluated were HER4 positive for membrane staining by IHC using E200. The scoring criteria for determining the HER4 score was based on the system used to score HER2, however a positive score indicated any membrane staining and therefore a 1+, 2+ or 3+ score was considered HER4-positive. 4B5 exhibited similar staining patterns as SP3 in co-expressing HER4 and HER2 tissues indicating that 4B5 was detecting only the HER2 antigen. Eighteen cases were HER4-positive by E200 and level 0 by 4B5 including a HER4 level 3+ case. Conclusions: PATHWAY HER2 4B5, a clinically relevant pharmacodiagnostic antibody for detecting HER2 expression in breast carcinoma, does not demonstrate cross reactivity to HER4 in IHC of FFPE clinical tissues.

The assessment of adeno-associated vectors as potential intrinsic treatments for brainstem axon regeneration

BACKGROUND

Adeno-associated virus (AAV) vector-mediated transgene expression is a promising therapeutic to change the intrinsic state of neurons and promote repair after central nervous system injury. Given that numerous transgenes have been identified as potential candidates, the present study demonstrates how to determine whether their expression by AAV has a direct intrinsic effect on axon regeneration.

METHODS

Serotype 2 AAV-enhanced green fluorescent protein (EGFP) was stereotaxically injected into the brainstem of adult rats, followed by a complete transection of the thoracic spinal cord and Schwann cell (SC) bridge implantation.

RESULTS

The expression of EGFP in brainstem neurons labeled numerous axons in the thoracic spinal cord and that regenerated into the SC bridge. The number of EGFP-labeled axons rostral to the bridge directly correlated with the number of EGFP-labeled axons that regenerated into the bridge. Animals with a greater number of EGFP-labeled axons rostral to the bridge exhibited an increased percentage of those axons found near the distal end of the bridge compared to animals with a lesser number. This suggested that EGFP may accumulate distally in the axon with time, enabling easier visualization. By labeling brainstem axons with EGFP before injury, numerous axon remnants undergoing Wallerian degeneration may be identified distal to the complete transection up to 6 weeks after injury.

CONCLUSIONS

Serotype 2 AAV-EGFP enabled easy visualization of brainstem axon regeneration. Rigorous models of axonal injury (i.e. complete transection and cell implantation) should be used in combination with AAV-EGFP to directly assess AAV-mediated expression of therapeutic transgenes as intrinsic treatments to improve axonal regeneration.

Familial Aggregation of Morbid Obesity

Recent studies have shown major gene effects for obesity in randomly ascertained families. To investigate the familial aggregation of a specific subset of obesity, which is particularly prone to medical complications, families with morbid obesity were studied. This condition occurs in 1%-2% of the population and is defined as 45.5 kg (100 pounds) or more over ideal weight. First-degree relatives of 221 morbidly obese probands (1560 adults) were identified, and height and weight (current and greatest) were obtained from each family member. Morbid obesity occurred in the family members of the probands 8 times more often than in the general population. Of the morbidly obese probands, 48% had one or more first-degree relatives who were also morbidly obese compared to a 6% population estimate. By the ages of 20-24, 12% of the morbidly obese probands were already 45.5 kg or more overweight, and 45% were 22.7 kg (50 pounds) or more overweight. There was little difference in the prevalence of familial morbid obesity by the gender of the probands: 47% of the male probands and 48% of the female probands had another morbidly obese relative, while 67% and 53% of the early onset (before age 25) male and female probands, respectively, had one or more first-degree relatives who were also morbidly obese. In addition to the extreme degree of familial aggregation, the prevalence of morbid obesity in parent-offspring sets was calculated within the morbidly obese families. Morbidly obese families who have one or two morbidly obese parents have a 2.6 times increased risk (p<0.002) of having one or more morbidly obese adult offspring, compared to families who have neither parent morbidly obese. Evidence for trimodality of the body mass index distribution was found for each gender (p = 0.0006 for male relatives and p = 0.075 for female relatives). The strong familial aggregation of morbid obesity indicates the need for further understanding of the genetic determinants of this extreme clinical disorder and how environmental factors affect the genetic expression of the trait.

IL-24 is expressed during wound repair and inhibits TGFalpha-induced migration and proliferation of keratinocytes

Interleukin (IL)-24 is the protein product of melanoma differentiation-associated gene 7 (MDA-7). Originally identified as a tumor suppressor molecule, MDA-7 was renamed IL-24 and classified as a cytokine because of its chromosomal location in the IL-10 locus, its mRNA expression in leukocytes, and its secretory sequence elements. We previously reported that IL-24 is expressed by cytokine-activated monocytes and T lymphocytes. Here, we show that IL-24 is expressed in keratinocytes during wound repair. Paraffin-embedded tissues prepared from human skin sampled at days 2, 6, and 10 after wounding were examined by immunohistochemistry for the expression of IL-24. Protein expression was detected in the keratinocyte population with maximum expression at days 2 and 6, and no expression by day 10 (four of four subjects). In vitro studies showed that cytokines involved in wound repair, most notably transforming growth factor alpha (TGFalpha), TGFbeta, IFNgamma, and IFNbeta, upregulated IL-24 protein expression in normal human epidermal keratinocytes (NHEKs). Examination of the function of IL-24 in both in vitro wound repair and migration assays demonstrated that IL-24 inhibits TGFalpha-induced proliferation and migration of NHEKs. These data support the hypothesis that IL-24 functions during an inflammatory response in the skin by inhibiting the proliferation and migration of keratinocytes.

Molecular mechanisms for the activity of PX-478, an antitumor inhibitor of the hypoxia-inducible factor-1alpha

We have reported previously that PX-478 (S-2-amino-3-[4'-N,N,-bis(chloroethyl)amino]phenyl propionic acid N-oxide dihydrochloride) has potent antitumor activity against a variety of human tumor xenografts associated with the levels of the hypoxia-inducible factor-1alpha (HIF-1alpha) within the tumor. We now report that PX-478 inhibits HIF-1alpha protein levels and transactivation in a variety of cancer cell lines. Hypoxia-induced vascular endothelial growth factor formation was inhibited by PX-478, whereas baseline levels of vascular endothelial growth factor in normoxia were unaffected. Studies of the mechanism of PX-478 action showed that HIF-1alpha inhibition occurs in both normoxia and hypoxia and does not require pVHL or p53. In addition, PX-478 decreases levels of HIF-1alpha mRNA and inhibits translation as determined by 35S labeling experiments and reporter assays using the 5' untranslated region of HIF-1alpha. Moreover, to a lesser extent, PX-478 also inhibits HIF-1alpha deubiquitination resulting in increased levels of polyubiquitinated HIF-1alpha. The inhibitory effect of PX-478 on HIF-1alpha levels is primarily due to its inhibition of translation because HIF-1alpha translation continues in hypoxia when translation of most proteins is decreased. We conclude that PX-478 inhibits HIF-1alpha at multiple levels that together or individually may contribute to its antitumor activity against HIF-1alpha-expressing tumors.

Mineral uptake in tobacco leaf discs during different developmental stages of shoot organogenesis

Relationships between mineral uptake and tobacco shoot organogenesis were investigated during three morphogenic phases: phase 1, days 0-10, pre-meristem formation; phase 2, days 10-20, meristem initiation and formation; and phase 3, days 20-35, growth and differentiation of induced meristems into leafy shoots. The mineral content of both shoot-forming (SF) and non-shoot-forming (NSF) media was examined over the 35-day culture period. Both SF and NSF explants rapidly consumed iron during phase 1. Nitrate uptake in SF explants was high and independent of explant growth during phases 1 and 2, but greatest and strongly correlated with growth during phase 3. Phosphorus uptake was highest in SF explants during phases 2 and 3, and correlated with explant growth. Uptake of potassium, calcium and sulphur was strongly associated with explant growth during phase 3 whereas magnesium uptake was only poorly correlated with growth. Results from this study indicate that particular minerals may have an important role in regulating development as well as generally supporting growth.

The thioredoxin redox inhibitors 1-methylpropyl 2-imidazolyl disulfide and pleurotin inhibit hypoxia-induced factor 1alpha and vascular endothelial growth factor formation

Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that plays a critical role in tumor growth by increasing resistance to apoptosis and the production of angiogenic factors such as vascular endothelial growth factor (VEGF). HIF-1 is a heterodimer comprised of oxygen-regulated HIF-1alpha and constitutively expressed HIF-1beta subunits. The redox protein thioredoxin-1 (Trx-1), which is found at high levels in many human cancers, increases both aerobic and hypoxia-induced HIF-1alpha protein in cells leading to increased expression of HIF-regulated genes. We have investigated whether two cancer drugs that inhibit Trx-1 signaling, PX-12 (1-methylpropyl 2-imidazolyl disulfide) and pleurotin, decrease HIF-1alpha protein levels and the expression of downstream target genes. Treatment of MCF-7 human breast cancer and HT-29 human colon carcinoma cells with PX-12 and pleurotin prevented the hypoxia (1% oxygen)-induced increase in HIF-1alpha protein. HIF-1-trans-activating activity, VEGF formation, and inducible nitric oxide synthase were also decreased by treatment with PX-12 and pleurotin under hypoxic conditions. PX-12 and pleurotin also decreased HIF-1alpha protein levels and HIF-1 trans-activation in RCC4 renal cell carcinoma cells that constitutively overexpress HIF-1alpha protein because of loss of the pVHL gene, indicating that HIF-1alpha is inhibited independently of the pVHL pathway. HIF-1alpha and VEGF protein levels in MCF-7 tumor xenografts in vivo were decreased by PX-12 treatment of mice. The results suggest that inhibition of HIF-1alpha by Trx-1 inhibitors may contribute to the growth inhibitory and antitumor activity of these agents.

The absence of mitochondrial thioredoxin 2 causes massive apoptosis, exencephaly, and early embryonic lethality in homozygous mice

Thioredoxin 2 (Trx-2) is a small redox protein containing the thioredoxin active site Trp-Cys-Gly-Pro-Cys that is localized to the mitochondria by a mitochondrial leader sequence and encoded by a nuclear gene (Trx-2). Trx-2 plays an important role in cell viability and the regulation of apoptosis in vitro. To investigate the role of Trx-2 in mouse development, we studied the phenotype of mice that have the Trx-2 gene silenced by mutational insertion. Homozygous mutant embryos do not survive to birth and die after implantation at Theiler stage 15/16. The homozygous mutant embryos display an open anterior neural tube and show massively increased apoptosis at 10.5 days postcoitus and are not present by 12.5 days postcoitus. The timing of the embryonic lethality coincides with the maturation of the mitochondria, since they begin oxidative phosphorylation during this stage of embryogenesis. In addition, embryonic fibroblasts cultured from homozygous Trx-2-null embryos were not viable. Heterozygous mice are fertile and have no discernible phenotype visible by external observation, despite having decreased Trx-2 mRNA and protein. These results show that the mitochondrial redox protein Trx-2 is required for normal development of the mouse embryo and for actively respiring cells.

Penetration of levofloxacin into skin tissue after oral administration of multiple 750 mg once-daily doses

OBJECTIVE

To probe the pharmacokinetic basis for the use of levofloxacin for complicated skin and skin-structure infections (SSSIs) at a once-daily dosage of 750 mg by investigating its penetration into skin tissue.

METHOD

Ten healthy volunteers were administered three oral, once-daily 750 mg doses of levofloxacin, and levofloxacin concentrations were subsequently measured over time (0.5-24 h) in skin-punch biopsy tissue and plasma.

RESULTS

Skin tissue concentrations consistently exceeded those in plasma at every time point, with tissue/plasma ratios of 1.37 +/- 0.81 for peak concentration and 1.97 +/- 0.35 for area under the concentration versus time curve. Three of the ten subjects reported treatment-emergent adverse events (AEs) that were considered unrelated to treatment. An 11th subject who had enrolled in the study withdrew after AEs of mild severity that were possibly related to the study drug.

CONCLUSION

The results support the clinical usage of levofloxacin 750 mg once-daily for complicated SSSIs.

Absence of a pharmacokinetic interaction between digoxin and levofloxacin

BACKGROUND

Levofloxacin, a broad-spectrum fluoroquinolone, may enhance digoxin bioavailability by eliminating intestinal flora that metabolize digoxin. Moreover, levofloxacin, which is eliminated primarily by glomerular filtration and active tubular secretion, may alter the elimination rate of digoxin. Because of the narrow therapeutic index of digoxin, it is important to evaluate the potential for interaction with levofloxacin when administered concomitantly.

METHODS

This was a placebo-controlled, randomized, double-blind, two-phase crossover study. Twelve healthy subjects (six males and six females) received 500 mg twice/day oral doses of levofloxacin or placebo for 6 days and a single oral dose of 0.4 mg digoxin on the morning of study day 5 along with levofloxacin or placebo.

RESULTS

There was no significant effect of levofloxacin on the pharmacokinetics (Cmax, AUC, and other disposition parameters) of oral digoxin. Steady-state levofloxacin absorption and disposition kinetics were also similar in the presence or absence of digoxin.

CONCLUSIONS

Results of this study suggest that an important pharmacokinetic interaction between levofloxacin and digoxin is unlikely to occur when administered concomitantly.

Developmental patterns of protein expression in photoreceptors implicate distinct environmental versus cell-intrinsic mechanisms

The present study has examined the spatial and temporal expression patterns of various proteins associated with the structure and function of mature photoreceptor outer segments in the developing ferret's retina using immunocytochemistry and RT-PCR. One set of proteins, including rod opsin, arrestin, and recoverin, was detected progressively in photoreceptors as they became postmitotic, being expressed well before the differentiation of outer segments. A second set of proteins, including beta- and gamma-transducin, cGMP-phosphodiesterase, phosducin, rhodopsin kinase, rod cGMP-gated cation channel protein, and peripherin, displayed a contrasting temporal onset and pattern of spatial emergence. These latter proteins first became detectable either shortly before or coincident with outer segment formation, and were expressed simultaneously in both older and younger photoreceptor cells. A third set, the short wavelength-sensitive (SWS) and medium wavelength-sensitive (MWS) cone opsin proteins, was the last to be detected, but materialized in a spatio-temporal pattern reminiscent of the neurogenetic gradient of the cones. These different spatial and temporal patterns indicate that cellular maturation must play a primary role in regulating the onset of expression of some of these proteins, while extrinsic signals must act to coordinate the expression of other proteins across photoreceptors of different ages.

The minisatellite of the GPI/AMF/NLK/MF gene: interspecies conservation and transcriptional activity

Minisatellites are tandemly repeated DNA sequences found throughout the genomes of all eukaryotes. They are regions often prone to instability and hence hypervariability; thus repeat unit sequence is generally not conserved beyond closely related species. We have studied the minisatellite located in intron 9 of the human glucose phosphate isomerase (GPI) gene (also known as neuroleukin, autocrine motility factor, maturation and differentiation factor) and have found, by Zoo blotting coupled with PCR amplification and DNA sequencing, that similar repeat units are present in seven other species of mammal. There is also evidence for the presence of the minisatellite in chicken. The repeat unit does not appear to be present at any other locus in these genomes. Minisatellite DNA has been reported to be involved in recombination activity, control of gene expression of nearby gene(s) (both transcriptional and translational), whilst others form protein coding regions. The high level of conservation exhibited by the GPI minisatellite, coupled with the unique location, strongly suggests a functional role. Our results from transient and stable transfections using luciferase reporter constructs have shown that the GPI minisatellite region can act to increase transcription from the SV40 promoter, CMV promoter and the human GPI promoter.

Safety and pharmacokinetics of multiple 750-milligram doses of intravenous levofloxacin in healthy volunteers

The safety and pharmacokinetics of a once-daily high intravenous dose of levofloxacin (750 mg) in 18 healthy volunteers were studied in a double-blind, randomized, placebo-controlled, single-center parallel group study. Levofloxacin was well tolerated, and higher maximum concentration of drug in serum and area under the concentration-time curve values were achieved. For difficult-to-treat infections, high daily doses of levofloxacin may be beneficial, and intravenous administration may be preferred in certain clinical settings, such as when treating patients in intensive care units, warranting further evaluation.

Organization of the inner retina following early elimination of the retinal ganglion cell population: effects on cell numbers and stratification patterns

The present study has examined the effects of early ganglion cell elimination upon the organization of the inner retina in the ferret. The population of retinal ganglion cells was removed by optic nerve transection on the second postnatal day, and retinas were subsequently studied in adulthood. Numbers of amacrine and bipolar cells were compared in the nerve-transected and nerve-intact retinas of operated ferrets, while stratification patterns within the inner plexiform layer were compared in these and in normal ferret retinas. Early ganglion cell elimination was found to produce a 25% reduction in the population of glycine transporter-immunoreactive amacrine cells, and 18 and 15% reductions in the populations of parvalbumin and calbindin-immunoreactive amacrine cells, respectively. GABAergic amacrine cells were also reduced by 34%. The number of calbindin-immunoreactive displaced amacrine cells, by contrast, had increased in the ganglion cell-depleted retina, being three times their normal number. Other amacrine and bipolar cell types were unaffected. Despite these changes, the stratification patterns associated with these cell types remained largely intact within the inner plexiform layer. The present results demonstrate a class-specific dependency of inner retinal neurons upon the ganglion cell population in early postnatal life, but the ganglion cells do not appear to provide any critical signals for stratification within the inner plexiform layer, at least not after birth. Since they themselves do not produce stratified dendritic arbors until well after birth, the signals for stratification of the bipolar and amacrine cell processes should arise from other sources.

Effectiveness of levofloxacin for adult community-acquired pneumonia caused by macrolide-resistant Streptococcus pneumoniae: integrated results from four open-label, multicenter, phase III clinical trials

BACKGROUND

The rate of macrolide resistance among Streptococcus pneumoniae clinical isolates is rising. Coresistance to several unrelated classes of antimicrobial agents is common and may limit the treatment options available for the management of infections caused by this pathogen. Although the fluoroquinolones appear to retain activity against macrolide-resistant pneumococci, limited clinical data exist to support their use in this setting.

OBJECTIVE

This study integrated data from 4 clinical trials to determine whether the fluoroquinolone levofloxacin is an effective therapeutic agent for community-acquired pneumonia (CAP) caused by macrolide-resistant S. pneumoniae.

METHODS

Across the 4 trials, 271 adult patients with CAP were diagnosed with infections caused by S. pneumoniae; these constituted the intent-to-treat population. Clinical isolates obtained from each patient at admission were tested using broth microdilution for in vitro sensitivity to the macrolide erythromycin (minimum inhibitory concentration breakpoints: susceptible, < or =0.25 microg/mL; intermediate, 0.5 microg/mL; resistant, > or =1.0 microg/mL). All patients received levofloxacin (500 mg once daily for 7-14 days) and were analyzed at a posttherapy visit (2-5 days after completion of therapy) for clinical and microbiologic outcomes; in 3 trials, patients were also examined at a poststudy visit (14-28 days after completion of treatment). Clinical and microbiologic outcomes were analyzed in patients infected with macrolide-resistant and macrolide-susceptible S. pneumoniae.

RESULTS

A total of 235 evaluable patients infected with S. pneumoniae were identified from the 4 trials. Twenty-seven (11.5%) patients were infected with isolates resistant to erythromycin, of whom 26 (96.3%) were clinical successes. By comparison, the clinical success rate in patients infected with erythromycin-susceptible isolates was 97.7%.

CONCLUSIONS

These results suggest that if future studies demonstrate the clinical relevance of macrolide resistance, levofloxacin may be a useful therapeutic option in patients with CAP caused by macrolide-resistant S. pneumoniae. However, caution may be warranted to prevent overprescription of levofloxacin and other fluoroquinolones, given the potential for the development of resistance in S. pneumoniae.

Usefulness of cardiovascular family history data for population-based preventive medicine and medical research (the Health Family Tree Study and the NHLBI Family Heart Study)

Detailed medical family history data have been proposed to be effective in identifying high-risk families for targeted intervention. With use of a validated and standardized quantitative family risk score (FRS), the degree of familial aggregation of coronary heart disease (CHD), stroke, hypertension, and diabetes was obtained from 122,155 Utah families and 6,578 Texas families in the large, population-based Health Family Tree Study, and 1,442 families in the NHLBI Family Heart Study in Massachusetts, Minnesota, North Carolina, and Utah. Utah families with a positive family history of CHD (FRS > or =0.5) represented only 14% of the general population but accounted for 72% of persons with early CHD (men before age 55 years, women before age 65 years) and 48% of CHD at all ages. For strokes, 11% of families with FRS > or =0.5 accounted for 86% of early strokes (<75 years) and 68% of all strokes. Analyses of >5,000 families sampled each year in Utah for 14 years demonstrated a gradual decrease in the frequency of a strong positive family history of CHD (-26%/decade) and stroke (-15%/decade) that paralleled a decrease in incidence rates (r = 0.86, p <0.001 for CHD; r = 0.66, p <0.01 for stroke). Because of the collaboration of schools, health departments, and medical schools, the Health Family Tree Study proved to be a highly cost-efficient method for identifying 17,064 CHD-prone families and 13,106 stroke-prone families (at a cost of about $27 per high-risk family) in whom well-established preventive measures can be encouraged. We conclude that most early cardiovascular events in a population occur in families with a positive family history of cardiovascular disease. Family history collection is a validated and relatively inexpensive tool for family-based preventive medicine and medical research.

Frequency of the R3500Q mutation of the apolipoprotein B-100 gene in a sample screened clinically for familial hypercholesterolemia in Hungary

Familial hypercholesterolemia (FH) and familial defective apolipoprotein B-100 (FDB) cause early onset of coronary heart diseases (CHD). According to the recommendations of the international MEDPED program, we tried to find FH cases. We analyzed 73 FH probands and their 304 first-degree relatives. A total of 39 probands were found from the 21000 subjects screened (1:538) from family doctors' registers recording all citizens, while the remaining 34 were derived from screened patients from lipid clinics. In our FH probands, four cases of FDB (R3500Q mutation) were diagnosed with allele-specific PCR, and the mutation was also detectable in five cases out of seven living family members. In the remaining 69 FH families, 156 people were diagnosed clinically with FH, and 31.8% of the males (against 13% of the not clinically diagnosed FH males, P<0.01), and 32.4% of the females (against 13.5% of the not clinically diagnosed FH females, P<0.01) suffered from early onset CHD. The plasma total cholesterol level of the FDB patients, especially in the younger patients, was very close to normal values. Therefore, the FDB patients seem to be under-represented in this type of survey. Because FDB is one of the independent causes of early onset CHD, the R3500Q mutation should be considered in families with a high frequency of cardiovascular diseases.

Plasma homocysteine and its association with carotid intimal-medial wall thickness and prevalent coronary heart disease: NHLBI Family Heart Study

Mildly elevated plasma total homocysteine (tHcy) levels have been associated with increased risk of coronary heart disease (CHD). Carotid artery intimal-medial wall thickening is a predictor of cardiovascular disease and has been previously shown to be positively associated with plasma tHcy in studies of asymptomatic subjects. In the current study we examined 1467 subjects with regard to their fasting plasma tHcy levels and intimal-medial wall thickness as measured by B-mode ultrasound and early onset CHD. The results showed that there is a significant positive association between plasma tHcy levels and carotid-artery wall thickness in participants 55 years or older even after the tHcy levels are adjusted for age, smoking and anti-hypertensive medication. The direction and magnitude of the relationship is similar although the result was not statistically significant in younger participants ( < 55 years). Early onset CHD at any age was not significantly different across the tHcy quintiles. The lack of an association of tHcy and CHD in the presence of a positive association with intimal-medial wall thickening may be a reflection of increased statistical power of quantitative versus qualitative traits. We conclude that the present finding of a positive association between tHcy and intimal-medial wall thickness strengthens the in vitro finding of the stimulating effect of homocysteine on vascular smooth muscle cell growth. Vascular smooth muscle cell proliferation may be an important mechanism through which mildly elevated plasma tHcy promotes atherosclerosis.

NHLBI family blood pressure program: methodology and recruitment in the HyperGEN network. Hypertension genetic epidemiology network

PURPOSE

Hypertension is a common precursor of serious disorders including stroke, myocardial infarction, congestive heart failure, and renal failure in whites and to a greater extent in African Americans. Large genetic-epidemiological studies of hypertension are needed to gain information that will improve future methods for diagnosis, treatment, and prevention of hypertension, a major contributor to cardiovascular morbidity and mortality.

METHODS

We report successful implementation of a new structure of research collaboration involving four NHLBI "Networks," coordinated under the Family Blood Pressure Program. The Hypertension Genetic Epidemiology Network (HyperGEN) involves scientists from six universities and the NHLBI who seek to identify and characterize genes promoting hypertension. Blood samples and clinical data were projected to be collected from a sample of 2244 hypertensive siblings diagnosed before age 60 from 960 sibships (half African-American) with two or more affected persons. Nonparametric sibship linkage analysis of over one million genotype determinations (20 candidate loci and 387 anonymous marker loci) was projected to have sufficient power for detecting genetic loci promoting hypertension. For loci showing evidence for linkage in this study and for loci reported linked or associated with hypertension by other groups, genotypes are compared in hypertensive cases versus population-based controls to identify or confirm genetic variants associated with hypertension. For some of these genetic variants associated with hypertension, detailed physiological and biochemical characterization of untreated adult offspring carriers versus non-carriers may help elucidate the pathophysiological mechanisms that promote hypertension.

RESULTS

The projected sample size of 2244 hypertensive participants was surpassed, as 2407 hypertensive individuals (1262 African-Americans and 1145 whites) from 917 sibships were examined. Detailed consent forms were designed to offer participants several options for DNA testing; 94% of participants gave permission for DNA testing now or in the future for any confidential medical research, with only 6% requesting restrictions for tests performed on their DNA. Since this is a family study, participants also are asked to list all first degree relatives (along with names, addresses, and phone numbers) and to indicate for each relative whether they were willing to allow study staff to make a contact. Seventy percent gave permission to contact some relatives; about 30% gave permission to contact all first degree relatives; and less than 1% asked that no relatives be contacted. Successes after the first four years of this study include: 1) productive collaboration of eight centers from six different locations; 2) early achievement of recruitment goals for study participants including African-Americans; 3) an encouraging rate of consent for DNA testing (including future testing) and relative contacting; 4) completed analyses of genetic linkage and association for several candidate gene markers and polymorphisms; 5) completed genotyping of random markers for over half of the full sample; and 6) early sharing of results among the four Family Blood Pressure Program networks for candidate and genome search analyses.

CONCLUSIONS

Experience after four years of this five-year program (1995-2000) suggests that the newly initiated NHLBI Network Program mechanism is fulfilling many of the expectations for which it was designed. It may serve as a paradigm for future genetic research that can benefit from large sample sizes, frequent sharing of ideas among laboratories, and prompt independent confirmation of early findings, which are required in the search for common genes with relatively small effects such as those that predispose to human hypertension.

Co-segregation of elevated LDL with a novel mutation (D92K) of the LDL receptor in a kindred with multiple lipoprotein abnormalities

Factors predisposing to the phenotypic features of familial combined hyperlipidemia have not been clearly defined. In the course of investigating familial coronary artery disease in Utah, we identified a three-generation family in which multiple members were affected with type IIa hyperlipoproteinemia (HLP IIa), type IIb hyperlipoproteinemia (HLP IIb), or type IV hyperlipoproteinemia (HLP IV). Because several family members had relatively severe low-density lipoprotein (LDL) cholesterol elevation, in order to dissect the possible contribution to the plasma lipoprotein abnormalities in this pedigree, we identified a novel point mutation in the low-density lipoprotein receptor (LDLR) gene, a G-to-A transition at nucleotide position 337 in exon 4. This change substituted lysine for glutamic acid at codon 92 (D92K) of the LDL receptor. By means of mutant allele-specific amplification we determined that the mutation co-segregated with elevated cholesterol and LDL cholesterol in the plasma of family members with HLP IIa and HLP IIb, but not with the elevated plasma triglycerides seen in HLP IIb and HLP IV patients. Thus, in families with apparent familial combined hyperlipidemia, a defective LDLR allele and other genetic or environmental factors that elevate plasma triglycerides may account for the multiple lipid phenotypes observed in this kindred.

Segregation analysis of cardiovascular reactivity to laboratory stressors

To better understand the contribution of major gene influences to individual differences in cardiovascular reactivity, we performed a segregation analysis on blood pressure responses to two laboratory tasks, mental arithmetic and bicycle exercise. The study population consisted of 1,451 adults (age > or = 18 years) who were members of 81 Utah pedigrees. Only 864 members performed the bicycle task because persons age 60 years or older or with heart disease were excluded. Blood pressure reactivity to mental arithmetic was defined as change from resting values, and reactivity to the bicycle task was defined as the difference between maximum blood pressure during exercise and resting values adjusted for the individual's workload. Complex segregation analysis and likelihood procedures were used to test for a major gene effect controlling blood pressure reactivity to each task. Two modifiers of the penetrance, age and sex, were considered parameters in these models. We found that diastolic blood pressure (DBP) but not systolic blood pressure reactivities to the mental arithmetic and bicycle exercise tasks were controlled by major gene effects. The best-fitting model, however, differed for the two tasks. For DBP reactivity to mental arithmetic, a major codominant model with gene frequency 0.10 was the best-fitting model; for the bicycle task, the best-fitting model was a mixed recessive model with gene frequency 0.21. Sex differences in DBP reactivity were significant in both tasks: the effect of age was significant only for the mental arithmetic task. These results suggest a significant genetic component for DBP reactivity to laboratory stressors.

Association between the alpha-adducin gene and hypertension in the HyperGEN Study

This report from the HyperGEN Study, one of four networks participating in the NHLBI-sponsored Family Blood Pressure Program, presents the results of an association study based on 822 white and 572 black subjects (cases and controls) participating in the HyperGEN Network from five geographically diverse field centers. All cases met the Joint National Committee on Detection and Treatment of High Blood Pressure (JNC VI) criteria for hypertension (Stage I or higher). Each subject was clinically examined for risk factors for hypertension as well as genotyped for the point mutation Gly460Trp at the alpha-adducin locus on chromosome 4p. In the white group, the prevalence of genotypes with one or more Trp alleles was 26% in normotensives, versus 33% in hypertensives randomly selected from the population, and 39% among the multiply affected hypertensive sibships. Overall, in whites, the Trp allele significantly increased the odds of hypertension (P = .0056), with an odds ratio (OR) of 1.73 (95% confidence interval [CI] = 1.17, 2.54). The alpha-adducin gene remained a significant independent predictor of hypertension in a multivariate logistic model even after correcting for other risk factors for hypertension, including gender, age, body mass index (BMI), smoking, LDL cholesterol, triglycerides, urine sodium (Na), and urine potassium (K), (OR = 1.55, 95% CI = 1.03, 2.34). Through the use of regression trees, several gene-by-environment interactions were implicated, suggesting that alpha-adducin appears to be a particularly important risk factor (OR = 4.2) for older (age > 60.5 years), less lean (BMI < 25.8 kg/m2) subjects with moderately high triglycerides (between 145.5 and 218.5 mg/dL). In the black group, the relationship was less clear. Overall, it was protective against hypertension. The prevalence of genotypes with one or more Trp alleles was 24% among normotensive versus 11% in hypertensive black subjects randomly selected from the population, and 13% among multiply affected hypertensive sibships, resulting in an OR of 0.48 (P = .0231; 95% CI = 0.25, 0.90). However, the Trp genotype was no longer a significant independent predictor of hypertension risk in the multivariate logistic model (OR = 0.79; 95% CI = 0.37, 1.67), suggesting that it may be operating through one or more of these other factors. Thus, we conclude that the alpha-adducin gene is a significant, independent risk factor for hypertension in whites, but not in blacks, and may play a particularly important role for subjects with certain constellations of other risk factors.

The Family Risk Score for coronary heart disease: associations with lipids, lipoproteins, and body habitus in a middle-aged bi-racial cohort: The ARIC study

PURPOSE

To examine the association between the Family Risk Score (FRS) for coronary heart disease (CHD) and body mass index (BMI), waist-to-hip ratio (WHR), high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol, triglycerides, and lipoprotein(a) protein [Lp(a)].

METHODS

FRS was computed from observed and expected CHD events using family data collected from 11467 black and white adults of the Atherosclerosis Risk in Communities Study (ARIC). BMI, WHR, and lipids adjusted for study center, race, education, BMI (except BMI), WHR (except for BMI and WHR), cigarette smoking, alcohol, and Keys' score were compared among low (FRS < -0.5), average (-0.5 to 0.5), and high (> 0.5) FRS using analysis of covariance. The association between FRS and these risk factors was compared to that for simpler estimates of family risk.

RESULTS

Adjusted means of BMI, WHR, LDL, LP(a), and triglycerides were positively associated with FRS, whereas HDL cholesterol was inversely associated with FRS. Of demographic and behavioral factors, cigarette smoking was most strongly associated with FRS. Based on additional comparisons of adjusted means, high vs. low levels of FRS appear to correlate better with CHD risk factors than do the simpler family history assessments.

CONCLUSIONS

In situations were genetic or clinical information is not available, FRS may be a favorable measure of familial burden for CHD.

An economic evaluation of levofloxacin versus cefuroxime axetil in the outpatient treatment of adults with community-acquired pneumonia

OBJECTIVE

To examine treatment costs of community-acquired pneumonia (CAP) in adult outpatients given oral (p.o.) levofloxacin or cefuroxime axetil as initial therapy.

STUDY DESIGN

Patients with a primary diagnosis of CAP were enrolled in a multicenter, prospective, randomized, open-label, active-controlled Phase III clinical trial. Both inpatients and outpatients were assigned to 1 of 2 treatment groups: (1) intravenous (i.v.) or p.o. levofloxacin; or (2) i.v. ceftriaxone and/or p.o. cefuroxime axetil.

METHODS

To make legitimate and meaningful cost comparisons between similar types of patients receiving drugs via the same route of administration (i.e., orally), this outpatient economic study examined the resource utilization of the 211 patients enrolled as outpatients who received oral formulations as initial treatment (levofloxacin, 103 patients; cefuroxime axetil, 108 patients). Resource utilization data and clinical trial data were collected concurrently. To generate cost estimates, Medicare cost estimates for resources were multiplied by the resource units used by patients in each treatment arm.

RESULTS

Cost estimates indicated a total cost difference that favored the levofloxacin group (base case: $169; sensitivity analysis: $223 [P = .008]). The results for the base case were not significant (P = .094). In addition, within the cost categories, there was a statistically significant study drug cost differential favoring levofloxacin ($86; P = .0001 for both the base case and sensitivity analysis).

CONCLUSION

Oral levofloxacin is less costly than oral cefuroxime axetil in the outpatient treatment of adults with CAP.

No evidence of linkage between the very-low-density lipoprotein receptor gene and fasting serum insulin or homeostasis model assessment insulin resistance index: the National Heart, Lung, and Blood Institute Family Heart Study

A major gene effect on the fasting insulin level and insulin resistance has been suggested in previous studies. Several candidate genes for insulin resistance in rare syndromes have been proposed. However, there has been limited success in finding genes for common forms of insulin resistance. There is accumulating evidence of a relationship between insulin resistance and a disturbance of free fatty acid (FFA) metabolism. The very-low-density lipoprotein (VLDL) receptor, which is associated with FFA metabolism, could serve as a possible candidate gene for insulin resistance. We performed linkage analyses between the VLDL receptor gene and fasting insulin and the homeostasis model assessment (HOMA) insulin resistance index (fasting insulin x fasting glucose/22.5) in 1,050 sibpairs participating in the phase II physical examination of the National Heart, Lung, and Blood Institute Family Heart Study (FHS). Data analyses were completed using the SIBPAL component of the SAGE software package (SAGE, Statistical Analysis for Genetic Epidemiology, Version 3.1; Computer program package available from the Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, OH, 1997). We did not find evidence for linkage of the fasting insulin or the HOMA insulin resistance index with a polymorphic marker at the VLDL locus (P = .316 and .402, respectively). Adjustment of fasting insulin and the HOMA insulin resistance index for the body mass index (BMI) did not change the results (P = .319 and .472, respectively). In conclusion, no evidence was found for a linkage between a locus controlling the fasting insulin level or HOMA insulin resistance index and a VLDL polymorphism in the present study. Additional adjustment of fasting insulin or the HOMA insulin resistance index for the BMI did not change the linkage results significantly.

Insulin and hypertension in the NHLBI Family Heart Study: a sibpair approach to a controversial issue

The association between insulin and hypertension remains equivocal. We therefore investigated insulin levels in 3037 normotensive and 1067 hypertensive subjects from the National Heart, Lung and Blood Institute (NHLBI) Family Heart Study (FHS) by two different approaches. First, we compared insulin levels between normotensive and 275 untreated hypertensive subjects. Insulin levels unadjusted as well as adjusted for age, sex, and center were significantly higher in hypertensives. After adjustment for body mass index (BMI), insulin remained significantly higher only in the diastolic hypertensive group (mean +/- SD 77.0 +/-36.7 pmol/L, P < .01) but not in the isolated systolic hypertensive group (67.0 +/- 38.2 pmol/L) when compared to normotensives (63.2 +/- 29.1 pmol/L). A sibpair analysis was then used that compared the intra-sibpair differences in insulin concentrations to the intra-sibpair differences in blood pressure (BP) levels. This approach was intended to control for the effects of genetic and residual shared environmental variance upon insulin levels. The intra-sibpair difference in insulin concentrations between concordant (diastolic and systolic deltaBP < 5 mm Hg) and discordant sibpairs (diastolic and systolic deltaBP > 15 and > 20 mm Hg, respectively) was no longer significantly different when adjusted for BMI (2.7 v 5.9 pmol/L for diastolic and -1.7 v -1.8 pmol/L for systolic BP). Even the random selection of one sibpair from each of the 326 families independently of insulin and BP levels did not result in a significant correlation between the intrasibpair differences in insulin and BP. Using an insulin resistance index instead of insulin did not change our findings. Our investigation in the FHS sample of families suggests that there is only a small, if any, influence of insulin levels on BP after adjustment for obesity-related sources of variation.

Primordial prevention of cardiovascular disease through applied genetics

Primordial prevention might be considered prevention of the development of disease at its earliest stages or early intervention on risk factors to eliminate increased risk in the first place. In this review we consider how knowledge of genetic causes of early cardiovascular disease can lead to directed screening and better treatment of high risk individuals. While gene therapy would be the most "primordial" approach to prevention of some diseases such as familial hypercholesterolemia, its practical application remains on the horizon. Nevertheless, there is much we can do now to prevent early deaths in genetically high risk patients. Here we consider epidemiology as the parent discipline for applied genetics and as integral to primordial prevention. With new knowledge of special susceptibility and new understanding of the interaction of genetics and exposures, prevention of individual high-risk in the first place is realizable. We summarize here the known and candidate genes influencing atherosclerosis, hypertension, and thrombosis; their diagnosis; and some useful preventive approaches. MEDPED, an international scheme for detection of risk in medical pedigrees, is described, along with the cost and social implications of its application as a preventive strategy.

A novel LDLR mutation, H190Y, in a Utah kindred with familial hypercholesterolemia

Heterozygous familial hypercholesterolemia (FH) is a serious disorder causing twice normal low-density lipoprotein (LDL) cholesterol levels early in childhood and very early coronary disease in both men and women. Treatment with multiple medications together with diet can normalize cholesterol levels in many persons with FH and prevent or delay the development of coronary atherosclerosis. Previously published blood cholesterol criteria greatly under-diagnosed new cases of FH among members of known families with FH and over-diagnosed FH among participants of general population screening. Thus, there is a need for accurate and genetically validated criteria for the early diagnosis of heterozygous FH. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To carry out molecular genetic diagnosis of the disease, we screened DNA samples for mutations in all 18 exons and the exon-intron boundaries of the LDL receptor gene (LDLR). Novel point mutations were identified in the proband: a C-to-T transversion at nucleotide position 631, causing substitution of tyrosine for histidine at codon 190 in exon 4 of the LDLR gene. The mutant allele-specific amplification method was used to examine 12 members of the family recruited for the diagnosis. This method helped to unequivocally diagnose 7 individuals as heterozygous for this particular LDLR mutation, while excluding the remaining 5 individuals from carrier status with FH.

Rods and cones project to the inner plexiform layer during development

Mature rod and cone photoreceptor cells extend terminals to the outer plexiform layer (OPL), where they form characteristic spherules or pedicles, synapsing with the second-order neurons of the inner nuclear layer (INL). The present study demonstrates that, prior to the formation of this connectivity, immature rods and cones in the ferret extend processes beyond the level of the horizontal cells and future OPL, reaching the inner plexiform layer (IPL). The number of processes extending to the IPL increases steadily as the population of photoreceptor cells expands postnatally, reaching a maximum 2 weeks after birth. These processes are immunopositive for synaptophysin, and they terminate in two strata occupied by the dendrites of amacrine cells and ganglion cells. The frequency of these processes declines rapidly during the third postnatal week, and they are no longer detectable by the fourth postnatal week. Their loss is neither a consequence of photoreceptor cell death nor is it due to selective protein trafficking mechanisms that render them immunonegative. Rather, these processes retract to the level of the OPL during this period, coincident with the maturation of bipolar and horizontal cell processes. These results demonstrate that, despite the clear presence of environmental signals presaging the formation of the OPL, photoreceptor terminals initially ignore them to grow beyond this level of the retina. Rather, they detect and respond to signals within the IPL during this period, terminating in proximity to the processes of other cells in the inner retina, where they may contribute to transient retinal circuitry during early development.

Effects of similarities in lifestyle habits on familial aggregation of high density lipoprotein and low density lipoprotein cholesterol: the NHLBI Family Heart Study

It is generally assumed that familial aggregation of lipids relates to both genetic and shared environmental factors. To determine the degree to which familial similarities in lifestyle habits explain familial aggregation of high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol, the authors analyzed 1994-1996 data from 2,284 US adult participants in the National Heart, Lung, and Blood Institute Family Heart Study. For men and women, respectively, HDL cholesterol correlated with alcohol consumption (r = 0.27, p < 0.001; r = 0.21, p < 0.001), exercise (r = 0.06, p = 0.05; r = 0.10, p = 0.002), and smoking (r = -0.09, p = 0.005; r = -0.13, p < 0.001). There was strong familial aggregation of HDL cholesterol (parent-child, r = 0.32; sibling-sibling, r = 0.29), but less than 10% was explained by lifestyle habits. For LDL cholesterol, weak correlations were found for intake of total fat (r = 0.06, p = 0.07) and fruits/vegetables (r = -0.09, p = 0.005) among men and for smoking (r = 0.10, p = 0.002) among women. LDL cholesterol correlated strongly among family members (parent-child, r = 0.24; sibling-sibling, r = 0.31), but essentially none of this aggregation related to the lifestyle factors studied. This study suggests that lifestyle factors have little effect on the familial aggregation of HDL and LDL cholesterol.

Pharmacokinetics and safety of high-dose and extended-interval regimens of levofloxacin in human immunodeficiency virus-infected patients

The pharmacokinetics of levofloxacin, administered in high doses and with extended dosing intervals, was studied in human immunodeficiency virus (HIV)-infected patients. Thirty patients received either 750 mg of the drug or a placebo once daily for 14 days, followed by 750 mg or 1,000 mg of the drug or a placebo three times weekly for an additional 14 days. Levofloxacin disposition was characterized by rapid oral absorption, with peak concentrations occurring approximately 1.5 h after dosing and elimination half-lives from 7.2 to 9.4 h. The overall incidence of any adverse effect was 70% (1,000 mg) to 95% (750 mg) for levofloxacin-treated patients and 71% for those taking the placebo. Levofloxacin pharmacokinetic parameters for HIV-infected patients were consistent with those observed in studies of healthy volunteers.

Evidence for a major gene accounting for mild elevation in LDL cholesterol: the NHLBI Family Heart Study

Studies of rare Mendelian disorders of low density lipoprotein cholesterol (LDL-C) metabolism have identified specific genetic mutations in the LDL receptor and apolipoprotein B. Although these rare mutations account for a small proportion of LDL-C variation, twin and adoption studies indicate that at least 50% of the overall LDL-C observed variation is genetically determined. In a heterogeneous sample of 3227 subjects from the NHLBI Family Heart Study collected from four US centres, we find evidence for a common major gene accounting for mild elevations (1.25 standard deviations) in LDL-C. The analysis favored a recessive model with a frequency of 0.52 for the gene influencing elevated LDL-C, phenotypic means of 113 mg/dl for the normal genotypes and 146 mg/dl for the abnormal genotype, and a significant polygenic heritability. This statistically-inferred major gene accounted for 24% of the variation in LDL-C, with polygenes accounting for another 28% of the variation. Using parameters for major gene transmission estimated in the segregation analysis, LDL-C showed no linkage to the LDL receptor gene (LDLR), nor to the apolipoprotein E gene (APOE), nor to the cholesterol 7alpha-hydroxylase gene (CYP7A1), indicating the major gene effect influencing mild elevation in LDL-C is not explained by any of these candidate loci.

Familial hypercholesterolemia in Utah kindred with novel 2412-6 Ins G mutations in exon 17 of the LDL receptor gene

Familial hypercholesterolemia (FH) is a monogenic disorder associated with primary hypercholesterolemia. FH is characterized by autosomal co-dominant inheritance with strikingly elevated LDL-cholesterol, the presence of xanthoma and premature atherosclerosis. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To determine the genetic etiology of the lipoprotein abnormalities, we screened DNA samples from the family for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein receptor (LDLR) gene. Novel point mutations were identified in the proband: a one-base insertion of G to a five-G stretch at nucleotides 2412-6 (codons 783-785), causing a frameshift in exon 17 of the LDL receptor gene. The direct sequencing method was used to examine six members of the family recruited for the diagnosis. This method helped to unequivocally diagnose the five individuals as heterozygous for this particular LDL receptor mutation. This method also helped us to diagnose with FH, or to exclude from carrier status, three children between ages 6 and 11.

Familial hypercholesterolemia in Utah kindred with novel R103W mutations in exon 4 of the LDL receptor gene

Heterozygous familial hypercholesterolemia (FH) is a serious disorder causing twice normal low-density lipoprotein cholesterol levels early in childhood and very early coronary disease in both men and women. Previously published blood cholesterol criteria greatly under-diagnosed new cases of FH among members of known families with FH and over-diagnosed FH among participants of general population screening. Thus, there is a need for accurate and genetically validated criteria for the early diagnosis of heterozygous FH. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To carry out molecular genetic diagnosis of the disease, we screened DNA samples for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein (LDL) receptor gene. Novel point mutations were identified in the proband: a C-to-T transversion at nucleotide position 369, causing substitution of Tryptophan for Arginine at codon 103 in exon 4 of the LDL receptor gene. The SSCP method was used to examine seven members of the family recruited for the diagnosis. This method helped to unequivocally diagnose only the proband as heterozygous for this particular LDL receptor mutation while excluding the remaining six individuals from carrier status with FH.

Evidence for a third genetic locus causing familial hypercholesterolemia. A non-LDLR, non-APOB kindred

Monogenically inherited hypercholesterolemia is most commonly caused by mutations at the low density lipoprotein receptor (LDLR) locus causing familial hypercholesterolemia (FH) or at the apolipoprotein B (APOB) locus causing the disorder familial defective apoB (FDB). Probands from 47 kindreds with a strict clinical diagnosis of FH were selected from the Cardiovascular Genetics Research Lipid Clinic, Utah, for molecular genetic analysis. Using a combination of single-strand conformation polymorphism (SSCP) and direct sequencing, 12 different LDLR gene mutations were found in 16 of the probands. Three of the probands were carriers of the APOB R3500Q mutation. In five of the remaining 28 pedigrees where no mutation had been detected, samples from enough relatives were available to examine co-segregation with the LDLR region using the microsatellite marker D19S221, which is within 1 Mb centromeric of the LDLR locus, and D19S394, sited within 150 kb telomeric of the LDLR locus. In four of the families there was strong evidence for co-segregation between the LDLR locus and the phenotype of hypercholesterolemia, but in one large family with 18 living affected members and clear-cut bimodal hypercholesterolemia, there were numerous exclusions of co-segregation. Using length polymorphic markers within and outside the APOB gene, linkage of phenotype in this family to the APOB region was similarly excluded. In this large family, the degree of hypercholesterolemia, prevalence of tendon xanthomata, and occurrence of early coronary disease were indistinguishable from the other families studied. In summary, the data provide unequivocal evidence that a third locus can be etiological for monogenic familial hypercholesterolemia and should be reinvigorating to research in this field.

Enhanced blood pressure response to mild sodium reduction in subjects with the 235T variant of the angiotensinogen gene

The relationship of high salt intake to elevated blood pressure levels has been demonstrated in most populations by cross-sectional, longitudinal, physiological, and clinical intervention studies. Variation within the angiotensinogen gene has been implicated in the genetic control of blood pressure levels and has been suggested to contribute to increased salt sensitivity. A total of 86 hypertensive men and women who had never been treated and who had participated in a 6-month randomized, placebo-controlled, clinical trial of low-sodium mineral salt (19% reduction in urinary sodium versus 12% increase in placebo group) were genotyped at the angiotensinogen M235T locus to test the hypothesis that the 235T allele is associated with a significant blood pressure response to a sodium reduction intervention whereas the 235M allele is not. After adjustment for gender and baseline blood pressure, persons with the TT and MT genotypes showed significant systolic blood pressure reductions on mineral salt compared with control subjects (P = .02 and P = .001, respectively) but not persons with the MM genotype (P = .10). Net adjusted diastolic blood pressure reductions also showed greater significance for persons with the TT and MT genotypes than for persons with the MM genotype (P = .08, P = .01, and P = .83, respectively). The net adjusted systolic and diastolic blood pressure reduction was -8.6/-3.9 mm Hg for persons with the TT genotype, -9.0/-5.2 mm Hg for the MT genotype, and -5.3/-1.0 mm Hg for the MM genotype. We conclude that the 235T allele of the angiotensinogen gene is associated with greater blood pressure decreases than the 235M allele after a sodium reduction intervention. The angiotensinogen gene accounts for some of the interindividual variation of the blood pressure response to sodium reduction.

No linkage of the lipoprotein lipase locus to hypertension in Caucasians

OBJECTIVE

A previous study has shown significant linkage of five markers near the lipoprotein lipase locus to systolic blood pressure, but not to diastolic blood pressure, in nondiabetic members of 48 Taiwanese families selected for noninsulin-dependent diabetes. However, lipoprotein lipase markers did not appear strongly linked to systolic blood pressure in a study of Mexican-Americans using a variety of selection schemes. The objective of the current study was to test whether markers near the lipoprotein lipase gene were linked to hypertension in Caucasians.

DESIGN

To test for linkage of genetic markers in or near the lipoprotein lipase gene to hypertension in Caucasians, two sets of Caucasian hypertensive sibships were genotyped. The samples included 261 sibships (431 effective sibpairs) from four field centers of the National Heart, Lung and Blood Institute Family Heart Study and 211 sibships (282 effective sibpairs) from the Health Family Tree database in Utah.

RESULTS

Two highly polymorphic markers in or near the lipoprotein lipase gene showed no evidence of excess allele sharing in either set of hypertensive sibships. Combining the two datasets resulted in 653 and 713 effective sibpairs for the two markers, sharing 0.495 +/- 0.30 and 0.486 +/- 0.28 alleles identical by descent compared to an expected sharing of 0.50. Multipoint analysis of the two loci also did not show linkage (P = 0.95).

CONCLUSIONS

We conclude that the lipoprotein lipase locus and nearby regions do not appear to be linked to hypertension in Caucasians.

Lipoprotein(a) interactions with lipid and non-lipid risk factors in patients with early onset coronary artery disease: results from the NHLBI Family Heart Study

BACKGROUND

A positive interaction between high plasma lipoprotein(a) [Lp(a)] and unfavorable plasma lipid levels has been reported to result in very high risk for premature coronary artery disease (CAD). We further examined this issue for men and women with early onset CAD. We also examined potential interactions between Lp(a) and non-lipid risk factors.

METHODS AND RESULTS

In 338 men and women with early onset CAD (most with a positive family history of early CAD) and 480 general population controls, we measured Lp(a), lipids and other risk factors. In univariate analysis, relative odds for CAD was 1.7 (P = 0.002) for plasma Lp(a) >50 mg/dl. Elevated Lp(a) level was found to interact with adjusted plasma total/high density lipoprotein (HDL) cholesterol such that when Lp(a) was over 50 mg/dl and adjusted plasma total/HDL cholesterol >5.8, relative odds for CAD were 8.0-9.6 (P<0.0001) in multiple logistic regression. Non-lipid risk factors were generally found to multiply the risk associated with Lp(a) (as predicted by logistic regression) without evidence for interaction.

CONCLUSIONS

We find evidence that Lp(a) does interact positively with adjusted plasma total/HDL cholesterol ratio. Aggressive risk factor intervention, especially for lipids, in those with elevated Lp(a) therefore appears indicated.

Familial hypercholesterolemia kindred in Utah with novel C54S mutations of the LDL receptor gene

In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To determine the genetic etiology of the lipoprotein abnormalities, we screened DNA samples for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein (LDL) receptor gene. Novel point mutations were identified in the proband: a T-to-A transversion at nucleotide position 223, causing substitution of Ser for Cys at codon 54 in exon 3 of the receptor gene. This amino acid replacement would disrupt one of the disulfide bonds necessary for maintenance of the secondary structure of the repeat at the N-terminal of the receptor, prevent correct folding of the receptor, and result in defective intracellular transport of the receptor.