Insulin-like growth factor I disparately regulates prolactin and growth hormone synthesis and secretion: studies using the teleost pituitary model

Although insulin-like growth factor I (IGF-I)'s inhibition of GH release is well documented, little is known of its control of GH synthesis at the posttranscriptional level. The manner by which IGF-I alters PRL synthesis and secretion is also unclear. This study was undertaken to examine the role IGF-I plays in regulating in vitro PRL and GH synthesis and release using the teleost pituitary model system. This model allows for isolation of nearly homogenous populations of distinct pituitary cell types that can be cultured in a completely defined, hormone-free medium. Tissues containing PRL cells and those consisting of GH cells were dissected from pituitaries of hybrid striped bass and exposed to varying concentrations of IGF-I, IGF-II, and insulin for 18-20 h. Exposure to graded doses of IGF-I markedly stimulated fractional, total, and newly synthesized PRL release in a dose-dependent fashion (ED50 for fractional release, 35 ng/ml or 4.6 nM; P < 0.0001). IGF-II and insulin also increased PRL release, but only at 10-fold higher concentrations than the lowest effective IGF-I dose. The total PRL content in the incubations and PRL synthesis, as measured by [35S]methionine incorporation, were not altered by IGF-I. By contrast, IGF-I potently reduced GH release (ED50, 29 ng/ml or 3.8 nM; P < 0.0001) and synthesis. Both 100 and 1000 ng/ml IGF-I decreased newly synthesized GH and total GH content (P < 0.001). Insulin and IGF-II mimicked IGF's action in attenuating GH release, but only at 10- to 11-fold higher concentrations. Taken together, these findings clearly indicate that IGF-I disparately regulates PRL and GH synthesis and secretion. We show that the effects of IGF-I on pituitary hormone release occur in a variety of species, suggesting that its actions are well conserved. The inhibition of GH release and synthesis by IGF-I probably reflects a negative feedback loop for maintaining tight control over GH cell function. These findings further indicate that IGF-I is a potent and specific secretagogue of PRL release in vertebrates.

Pathogenesis of Cryptococcus neoformans is associated with quantitative differences in multiple virulence factors

Two isolates of Cryptococcus neoformans were previously described as being highly divergent in their level of capsule synthesis in vivo and in their virulence for mice. The highly virulent isolate (NU-2) produced more capsule than a weakly virulent isolate (184A) in vitro under tissue culture conditions and in vivo. This investigation was done to determine if there were differences between the two isolates in other factors that might also contribute to virulence. Growth rate was not a factor as NU-2 grew more slowly than 184A. Based on PCR fingerprinting the two isolates were genetically different providing an opportunity to examine differences in multiple virulence traits. Quantitative analysis revealed that NU-2 expressed significantly more melanin and mannitol than did 184A. Although the isolates expressed the same capsular chemotype, NU-2 produced an additional structure reporter group (SRG) under tissue culture conditions that was not present when grown in glucose salts/urea/basal medium (GSU). Capsular polysaccharide SRGs of 184A were unaffected by shifting the growth conditions from GSU to tissue culture conditions. Our results suggest that pathogenesis of a C. neoformans strain is dictated by the quantitative expression of the strain's combined virulence traits. Regulators of the expression of these genes may be playing key roles in virulence.

Use of hair dyes, hematopoietic neoplasms, and lymphomas: a literature review. II. Lymphomas and multiple myeloma

We review studies on hair dyes and lymphomas and multiple myeloma (MM). A computerized literature search for the years 1966 through 1996 was conducted. Data were extracted using a standardized form that recorded study design, study population, type of cases, comparison group, sources of data on personal exposure to hair dyes, method of data collection, type of exposure data collected, covariates, and results. This review identified 10 epidemiologic studies published in the English literature that examined personal use of hair dyes and lymphomas or MM. These studies include three evaluations of Hodgkin's disease, five of non-Hodgkin's lymphoma (NHL), two of lymphomas with type not specified, and six of MM. For Hodgkin's disease, one case-control study reported some positive associations with use of permanent hair dyes, whereas two cohort studies found no associations with ever use of hair dyes. For NHL and MM, several evaluations suggest associations with use of permanent dyes, particularly with duration, frequency, age at first use, and dark colors. However, these associations are not consistent within and between studies. For lymphomas with type not specified, one study was superseded by a more recent report with NHL specific data and a second study was limited by small numbers of exposed subjects. At this time, it is not possible to determine if the inconsistent associations between permanent hair dyes and NHL and MM reflect sampling variability or differences in methods between studies. Because an appreciable fraction of the population has potential exposure to permanent hair dyes, elucidation of such issues may be warranted with studies that include adequate numbers of exposed subjects and that elicit information on personal use of hair dyes over time.

Use of hair dyes, hematopoietic neoplasms, and lymphomas: a literature review. I. Leukemias and myelodysplastic syndromes

We review published epidemiologic studies on personal use of hair dyes and leukemias and myelodysplastic syndromes (MDS). A subsequent article will review studies on lymphomas and multiple myeloma. A computerized literature search for the years 1966 through 1996 was completed using MEDLINE. Data were extracted using a standardized form that recorded study design, study population, type of cases, comparison group, sources of data on personal exposure to hair dyes, method of data collection, type of exposure data collected, covariates, and results. The above search identified 13 epidemiologic studies on the possible association between personal use of hair dyes and leukemias and MDS. Although there are some reports of positive associations, overall the evidence linking personal use of hair dyes to various leukemia and MDS subgroups is weak. One cannot definitively rule out an association, however, because of the methodologic limitations, such as small numbers of exposed cases and lack of detailed exposure information. Any further research would need much better assessment of hair dye use, including product type, color frequency, duration, and changes in use over time, and adequate statistical power.

Do automated red cell exchanges relieve priapism in patients with sickle cell anemia?

Priapism is a dramatic, painful complication for some men afflicted by sickle cell anemia. Although the natural history remains unclear, many believe replacing the patient's abnormal red blood cells (RBCs) with normal RBCs by apheresis is effective. However, no controlled trials have demonstrated its effectiveness. We exchanged 7 men after medical management failed. All procedures reduced sickle hemoglobin levels to < 30%. Two patients underwent emergency automated red cell exchanges without any detumescence or reduction of pain. The remaining 5 patients were exchanged non-emergently; 4 experienced no detumescence or relief of pain. One adult experienced resolution 8 h postexchange. However, he had a history of "stuttering" priapism. All required decompression procedures. Automated RBC exchanges were not effective in achieving detumescence or reducing pain.

Collaborative multidisciplinary workshop report: clinical antimicrobial trials for primary and secondary prevention of atherosclerotic cardiovascular disease

The task assigned to the working group on Clinical Antimicrobial Trials for Primary and/or Secondary Prevention of Atherosclerotic Cardiovascular Disease was to evaluate the need for additional clinical antibiotic trials of a primary or secondary nature for the treatment of atherosclerotic heart disease and to suggest possible designs for future trials. In addition, the working group was to define the role of collaboration in answering research questions.

Insolvency and challenges of regulating providers that bear risk

Risk contracting and capitation are two widely used financial mechanisms that give incentives to health care providers to control costs. Risk-bearing arrangements have failed in a number of communities, however. This has shaken local markets, disrupting consumers' access to health care services and triggering losses for physicians and hospitals. It also has raised questions about the adequacy of related regulatory oversight, which holds important implications for local and national policy makers. This Issue Brief provides case studies of failed risk-contracting arrangements in two of the 12 communities that the Center for Studying Health System Change (HSC) tracks intensively--Northern New Jersey and Orange County, Calif.--and examines implications for policy makers.

Rising stars and raging diseases: the rhetoric and reality of Antebellum canonization

In an 1849 sketch, bookseller William R. Davis described the contents of a whimsical “curiosity shop,” stocked solely with clichés. Merchandise included “The finger that's in every body's pie,” “Some of the spice of Life,” “A rusty link from the bond of friendship,” “The bridle used in curbing the passions,” and “One of the bowels of the earth.” The humor of Davis's sketch rested on its ability to defamiliarize everyday tropes to the point where vehicle overwhelmed tenor, literalizing the figurative and making the reader aware of the submerged discourses upon which such figures relied. Davis's humorous exploration of conventional rhetoric resonates strongly today, for cultural historians have taken a comparable linguistic turn, exposing and exploring the figurative dimensions of ostensibly literal discourses. Recent studies in composition pedagogy, popular culture, theology, natural history, genre analysis, and historiography have all emphasized the extent to which figurative discourse structures and defines the very fields it purports to explain. As Hayden White argues, “All systems of knowledge begin … in a metaphorical characterization of something presumed to be unknown in terms of something presumed to be known, or at least familiar.” Yet while this linguistic self-consciousness has greatly inspired the study of, among other areas, traditional historiography, it has scarcely had an impact on our understanding of literary historiography. Few have studied antebellum figures of speech as closely as Davis, nor have they tested antebellum literary historical and critical theories by the standards or techniques of figurative analysis. Such an exercise, I contend, would reveal much about both the theory and practice of literary canonization in 19th-century America.

A comparison of the bronchodilator effect of salbutamol inhaled via Turbuhaler as two consecutive doses or as two divided doses at different time intervals

The aim of the study was to compare the bronchodilatory effect of 2x50 microg salbutamol inhaled via Turbuhaler(R) as two consecutive doses compared with two divided doses (50+50 microg) at different time intervals. The study was of a randomized, double-blind, crossover design. The patients inhaled two doses of 50 microg salbutamol immediately after each other and with a time interval between the doses of 1.5, 3, 5, or 10 mins. Forced expiratory volume in 1 s (FEV(1)) was measured before the first inhalation and at 1, 2. 5, 4.5, 9.5, 15, 20, 30, and 60 min after the first inhalation. Seventeen asthmatic patients (8 men) with a mean age of 32 years (range: 19-49 years), mean FEV(1) of 2.9 l (range: 1.7-3.9 l) and a mean FEV(1) in percentage of predicted normal value of 77% (range: 63-91%) participated. The mean reversibility 15 min after inhaling 100 microg salbutamol from pMDI was 23% (range: 16-35%). The mean maximum increase in FEV(1) from baseline ranged between 18.6% (consecutive doses) and 21.2% (1.5 min between doses), corresponding to a difference between the treatments of 0.06 l. There were no significant differences in maximum FEV(1) or time to reach maximum FEV(1) between the treatments. We were not able to show any clinically relevant differences in maximal bronchodilating effect, assessed as FEV(1), in stable asthmatics, when therapeutic doses of salbutamol were given via Turbuhaler either as two consecutive doses or as two divided doses separated by different time intervals.

Lysine-69 plays a key role in catalysis by ornithine decarboxylase through acceleration of the Schiff base formation, decarboxylation, and product release steps

Ornithine decarboxylase (ODC) is a pyridoxal-5'-phosphate-dependent (PLP) enzyme that catalyzes the biosynthesis of the polyamine putrescine. Similar to other PLP-dependent enzymes, an active site Lys residue forms a Schiff base with PLP in the absence of substrate. The mechanistic role of this residue (Lys-69) in catalysis by Trypanosoma brucei ODC has been studied by analysis of the mutant enzymes, in which Lys-69 has been replaced by Arg (K69R ODC) and Ala (K69A ODC). Analysis of K69A ODC demonstrated that the enzyme copurified with amines (e.g. putrescine) that were tightly bound to the active site through a Schiff base with PLP. In contrast, on the basis of an absorption spectrum of K69R ODC, PLP is likely to be bound to this mutant enzyme in the aldehyde form. Pre-steady-state kinetic analysis of the reaction of K69R ODC with L-Orn and putrescine demonstrated that the rates of both the product release (k(off.Put) = 0.0041 s(-)(1)) and the decarboxylation (k(decarb) = 0.016 s(-)(1)) steps were decreased by10(4)-fold in comparison to wild-type ODC. Further, the rates of Schiff base formation between K69R ODC and either substrate or product have decreased by at least 10(3)-fold. Product release remains as the dominant rate-limiting step in the reaction (the steady-state parameters for K69R ODC are k(cat) = 0.0031 s(-)(1) and K(m) = 0.18 mM). The effect of mutating Lys-69 on the decarboxylation step suggests that Lys-69 may play a role in the proper positioning of the alpha-carboxylate for efficient decarboxylation. K69R ODC binds diamines and amino acids with higher affinity than the wild-type enzyme; however, Lys-69 does not mediate substrate specificity. Wild-type and K69R ODC have similar ligand specificity preferring to bind putrescine over longer and shorter diamines. Kinetic analysis of the binding of a series of diamines and amino acids to K69R ODC suggests that noncovalent interactions in the active site of K69R ODC promote selective ligand binding during Schiff base formation.

International, collaborative assessment of 146,000 prenatal karyotypes: expected limitations if only chromosome-specific probes and fluorescent in-situ hybridization are used

The development of chromosome-specific probes (CSP) and fluorescent in-situ hybridization (FISH) has allowed for very rapid identification of selected numerical abnormalities. We attempt here to determine, in principle, what percentage of abnormalities would be detectable if only CSP-FISH were performed without karyotype for prenatal diagnosis. A total of 146 128 consecutive karyotypes for prenatal diagnosis from eight centres in four countries for 5 years were compared with predicted detection if probes for chromosomes 13, 18, 21, X and Y were used, and assuming 100% detection efficiency. A total of 4163 abnormalities (2.85%) were found including 2889 (69. 4%) (trisomy 21, trisomy 18, trisomy 13, numerical sex chromosome abnormalities, and triploidies) which were considered detectable by FISH. Of these, 1274 were mosaics, translocations, deletions, inversions, rings, and markers which would not be considered detectable. CSP-FISH is a useful adjunct to karyotype for high risk situations, and may be appropriate in low risk screening, but should not be seen as a replacement for karyotype as too many structural chromosome abnormalities will be missed.

The impact of hospital restructuring on social work services: a case study of a large, university-affiliated hospital in Canada

The study investigates the impact of organizational restructuring on social work practice at a large, university-affiliated hospital. The article first reviews relevant literature on the patient-focused care model and presents an overview of the study setting. Several hypotheses are then presented that informed the research process. Workload measurement, interview, and questionnaire data are analyzed to test these hypotheses. The results indicate that the shift to program management has had some intended effects, particularly regarding increases in direct services supporting patients. Social workers reported somewhat lower levels of job satisfaction than expected, which partly reflects the dismantling of the professional infrastructure. Finally, the authors discuss implications for the future of the social work profession under the program management model.

Mechanisms for induction of L-selectin loss from T lymphocytes by a cryptococcal polysaccharide, glucuronoxylomannan

Disseminated cryptococcosis is accompanied by cryptococcal polysaccharides in the serum and the lack of cellular infiltrates in infected tissues. Cryptococcal polysaccharides given intravenously to mice inhibit the influx of T lymphocytes into the sites of cell-mediated immune response. The focus here was to determine whether cryptococcal polysaccharides modulate the expression of molecules, such as L-selectin, that are important in extravasation of T cells. Cryptococcal glucuronoxylomannan (GXM), but not galactoxylomannan or mannoprotein, was found to cause loss of L-selectin from freshly isolated human T cells of both CD4 and CD8 subsets and from Jurkat cells. With the signaling-pathway inhibitors staurosporine (which inhibits protein kinase C) and herbimycin A (which inhibits protein tyrosine kinases), we showed that GXM or the cryptococcal culture filtrate antigen CneF directly induces L-selectin loss from CD4(+) and CD8(+) T cells via a herbimycin A-sensitive pathway(s) presumably involving one or more protein tyrosine kinases but not via a pathway involving protein kinase C. Loss of L-selectin from the T cells before the T cells have a chance to bind to L-selectin ligands on endothelial cells would be expected to prevent T-cell migration into inflamed tissues and/or lymph organs.

Cytogenetic evaluation of 1000 cases of chorionic villus sampling

BACKGROUND

Chorionic villus sampling (CVS) is used routinely as a first trimester diagnostic procedure for fetal karyotyping in at-risk pregnancies. The success of the procedure is dependent on the experience of the operator performing it. The objective of this study was to determine the relationship between an operatorcontrolled clinical and laboratory setting and the safety and reliability of CVS service.

PATIENTS AND METHODS

One thousand patients had a CVS procedure for a variety of indications, such as advanced maternal age, previous child with chromosome abnormality, etc. Both transcervical and transabdominal procedures were performed, according to placental location and uterine environment. For cytogenetic diagnosis, direct and short-term cultures were set up according to standard laboratory protocol.

RESULT

Cytogenetic results were obtained in 99.6% of studies with 94.5% normal (46,XX or 46,XY), with the remaining having a variety of numerical and structural chromosomal abnormalities. Maternal cell contamination was found in 2% of the first 262 cases, while the overall rate observed in the 1000 samples was 0.5%. Level II mosaicism was observed in 0.8% and level III mosaicism observed in 0.9% of cases, respectively. The overall rate of pregnancy loss of chromosomally normal pregnancies within 28 weeks of gestation was 2.8%. No limb reduction defects were seen in any infant post-CVS.

CONCLUSION

Our record demonstrates that experienced operators can deliver a safe and reliable CVS service.

Specificities of anti-sialyl-Tn and anti-Tn monoclonal antibodies generated using novel clustered synthetic glycopeptide epitopes

The fine specificities of MAbs generated using novel synthetic clustered STn and Tn glycopeptides as immunogens were compared with the anti-TAG-72 antibodies B72.3 and CC49. Hapten inhibition experiments demonstrated the specificity of several of the MAbs for STn and Tn expressed on ovine submaxillary mucin and tumor derived MUC-1 mucin. Amongst the STn specific MAbs only the B195.3 MAb shows absolute dependence on the presence of sialic acid and specificity to the simple disaccharide NANAA alpha2-6-GalNAc. Identification of tumor associated carbohydrate epitopes in cluster and monomer configurations are possible using MAbs detecting the defined structure specificities described herein.

Family physicians managing tuberculosis. Qualitative study of overcoming barriers

OBJECTIVE

To identify the types of non-clinical barriers family physicians face in the management of TB, and to suggest strategies for overcoming these barriers.

DESIGN

Qualitative study based on focus group discussions with family physicians and specialists in different types of practices.

SETTING

Private practices, community health centres, and family practice units in hospitals.

PARTICIPANTS

Family physicians and specialists working in different practice settings.

METHOD

At least one specialist participated in each focus group in order to understand possible differences in non-clinical barriers to TB management between family physicians and specialists.

MAIN FINDINGS

Physicians can identify many types of non-clinical obstacles to TB management. Some obstacles appear to be directly related to the organization of family practice medicine, while others stem from the type of patient population seen or the stigma associated with TB. Some physicians question whether or not patient "noncompliance" is in fact a barrier to TB management. Many family physicians believe that they have readily available to them the expert opinion needed to manage TB effectively.

CONCLUSIONS

Some specific interventions, such as changes in TB guidelines, could overcome some of the obstacles identified. Differences among family physicians in the organization and nature of their practice, and in their understanding of their role in TB management, however, should be taken into account in developing interventions because such differences could influence both the need for, and receptivity to, any changes.

Submicroscopic deletions at 16p13.3 in Rubinstein-Taybi syndrome: frequency and clinical manifestations in a North American population

Rubinstein-Taybi syndrome (RTS) is a well delineated multiple congenital anomaly syndrome characterised by mental retardation, broad thumbs and toes, short stature, and specific facial features. The recent localisation of the disorder to 16p13.3 and subsequent identification of a submicroscopic deletion of this region in RTS patients led us to screen a large cohort of affected subjects using the RT1 probe. Among 64 patients with clinical evidence of RTS, seven (11%) had a deletion. Another patient had a translocation of the region without evidence of a deletion. The features of coloboma, growth retardation, naevus flammeus, and hypotonia have a positive predictive value for the presence of an RT1 deletion. Because of the relatively low frequency of deletions in RTS, the RT1 probe is useful in diagnostic confirmation, but has limited use as a screening tool.

Dubowitz syndrome in a boy without developmental delay: further evidence for phenotypic variability

Dubowitz syndrome is an autosomal recessive condition characterized by pre- and postnatal growth retardation, eczema, telecanthus, epicanthal folds, blepharophimosis, ptosis, and broadening of the bridge and tip of the nose. The initial patients described had varying degrees of mental retardation and there is little information about long-term developmental outcome. We present a boy with Dubowitz syndrome who does not have developmental delays, providing additional evidence that the phenotype includes normal neurodevelopmental status.