Corrugated nanowires as distributed Bragg reflectors

Distributed Bragg reflectors (DBRs), comprised of periodic refractive index changes, are widely used in optoelectronic devices as resonators, filters and sensors. The heterostructures required for DBRs can be difficult to implement in nanostructures due to poor compositional control on the nanoscale. In the present paper, simulation results are presented of the reflectance spectra from DBR structures that are implemented using periodic perturbations of a nanowire (NW) diameter, rather than heterostructures. The corrugated NW structure can produce a DBR stopband with reflectance near unity. The Bragg wavelength and stopband can be tuned by adjusting the pitch of the nanowire arrays, the corrugation depth, and the period of the corrugation. The proposed DBR structure presents a new paradigm for a wide range of nanoscale device applications.

Improving the yield of GaAs nanowires on silicon by Ga pre-deposition

GaAs nanowire (NW) arrays were grown by molecular beam epitaxy using the self-assisted vapor-liquid-solid method with Ga droplets as seed particles. A Ga pre-deposition step is examined to control NW yield and diameter. The NW yield can be increased with suitable duration of a Ga pre-deposition step but is highly dependent on oxide hole diameter and surface conditions. The NW diameter was determined by vapor-solid growth on the NW sidewalls, rather than Ga pre-deposition. The maximum NW yield with a Ga pre-deposition step was very close to 100%, established at shorter Ga deposition durations and for larger holes. This trend was explained within a model where maximum yield is obtained when the Ga droplet volume approximately equals the hole volume.

Simulation of optical absorption in conical nanowires

The optical absorptance from arrays of GaAs nanowires (NWs) was examined by the finite element method. Absorptance in cylindrical NWs, frustum nanocones (with base wider than the top) and inverted frustum nanocones (with top wider than the base) was compared. The introduction of higher order HE_1n modes, the red-shift of the HE_1n modes along the NW length due to NW tapering, and the red-shift of the modes due to increase of the overall NW diameter all contribute to a broadening of the absorption spectrum in conical NWs as compared to NWs with a constant diameter. The optical reflectance versus NW top diameter shows a minimum due to a balance between reflectance from the top of the NWs and reflectance from the substrate between NWs. The optimum geometry for photovoltaic energy conversion was determined from the total photocurrent. An optimum photocurrent of 26.5 mAcm^-2 was obtained, corresponding to a conical NW morphology with base diameter of 200 nm, top diameter of 110 nm, and length of 2000 nm. An optimized inverse tapered conical morphology gave comparable performance.

Modeling the dynamics of interface morphology and crystal phase change in self-catalyzed GaAs nanowires

The droplet contact angle and morphology of the growth interface (vertical, tapered or truncated facets) are known to affect the zincblende (ZB) or wurtzite (WZ) crystal phase of III-V nanowires (NWs) grown by the vapor-liquid-solid method. Here, we present a model which describes the dynamics of the morphological evolution in self-catalyzed III-V NWs in terms of the time-dependent (or length-dependent) contact angle or top nanowire radius under varying material fluxes. The model fits quite well the contact angle dynamics obtained by in situ growth monitoring of self-catalyzed GaAs NWs in a transmission electron microscope. These results can be used for modeling the interface dynamics and the related crystal phase switching and for obtaining ZB-WZ heterostructures in III-V.

Pediatric Quality of Life Inventory (PedsQL) 3.2 Diabetes Module for youth with Type 2 diabetes: reliability and validity

AIM

To test the measurement properties of the revised and updated Pediatric Quality of Life Inventory (PedsQL) 3.2 Diabetes Module originally developed in Type 1 diabetes in youth with Type 2 diabetes.

METHODS

The PedsQL 3.2 Diabetes Module and PedsQL Generic Core Scales were administered in a field test study to 100 young people aged 9-25 years with Type 2 diabetes. Factor analysis was conducted to determine the factor structure of the items.

RESULTS

The 15-item Diabetes Symptoms Summary Score and 12-item Type 2-specific Diabetes Management Summary Score were empirically derived through factor analysis. The Diabetes Symptoms and Type 2-specific Diabetes Management Summary Scores showed acceptable to excellent reliability across the age groups tested (α = 0.85-0.94). The Diabetes Symptoms and Type 2-specific Diabetes Management Summary Scores evidenced construct validity through large effect size correlations with the Generic Core Scales Total Scale Score (r = 0.67 and 0.57, respectively). HbA_1c was correlated with the Diabetes Symptoms and Type 2-specific Diabetes Management Summary Scores (r = -0.13 and -0.22). Minimal clinically important difference (MCID) scores were 5.91 and 7.39 for the Diabetes Symptoms and Type 2-specific Diabetes Management Summary Scores.

CONCLUSIONS

The PedsQL 3.2 Diabetes Module Diabetes Symptoms Summary Score and Type 2-specific Diabetes Management Summary Score exhibited satisfactory measurement properties for use as youth self-reported diabetes symptoms and diabetes management outcomes for clinical research and clinical practice for young people with Type 2 diabetes.

A longitudinal cohort study of HIV 'treatment as prevention' in gay, bisexual and other men who have sex with men: the Treatment with Antiretrovirals and their Impact on Positive And Negative men (TAIPAN) study protocol

BACKGROUND

Australia has increased coverage of antiretroviral treatment (ART) over the past decade, reaching 73% uptake in 2014. While ART reduces AIDS-related deaths, accumulating evidence suggests that it could also bolster prevention efforts by reducing the risk of HIV transmission ('treatment as prevention'). While promising, evidence of community-level impact of treatment as prevention on reducing HIV incidence among gay and bisexual men is limited. We describe a study protocol that aims to determine if scale up of testing and treatment for HIV leads to a reduction in community viraemia and, in turn, if this reduction is temporally associated with a reduction in HIV incidence among gay and bisexual men in Australia's two most populous states.

METHODS

Over the period 2009 to 2017, we will establish two cohorts making use of clinical and laboratory data electronically extracted retrospectively and prospectively from 73 health services and laboratories in the states of New South Wales and Victoria. The 'positive cohort' will consist of approximately 13,000 gay and bisexual men (>90% of all people living with HIV). The 'negative cohort' will consist of at least 40,000 HIV-negative gay and bisexual men (approximately half of the total population). Within the negative cohort we will use standard repeat-testing methods to calculate annual HIV incidence. Community prevalence of viraemia will be defined as the proportion of men with a viral load ≥200RNA copies/mm³, which will combine viral load data from the positive cohort and viraemia estimates among those with an undiagnosed HIV infection. Using regression analyses and adjusting for behavioural and demographic factors associated with infection, we will assess the temporal association between the community prevalence of viraemia and the incidence of HIV infection. Further analyses will make use of these cohorts to assess incidence and predictors of treatment initiation, repeat HIV testing, and viral suppression.

DISCUSSION

This study will provide important information on whether 'treatment as prevention' is associated with a reduction in HIV incidence at a community level among gay and bisexual men.

Relative risk of cardiovascular disease among people living with HIV: a systematic review and meta-analysis

OBJECTIVES

The aim of this study was to estimate the relative risk of cardiovascular disease (CVD) among people living with HIV (PLHIV) compared with the HIV-uninfected population.

METHODS

We conducted a systematic review and meta-analysis of studies from the peer-reviewed literature. We searched the Medline database for relevant journal articles published before August 2010. Eligible studies were observational and randomized controlled trials, reporting CVD, defined as myocardial infarction (MI), ischaemic heart disease, cardiovascular and cerebrovascular events or coronary heart disease among HIV-positive adults. Pooled relative risks were calculated for various groupings, including different classes of antiretroviral therapy (ART).

RESULTS

The relative risk of CVD was 1.61 [95% confidence interval (CI) 1.43-1.81] among PLHIV without ART compared with HIV-uninfected people. The relative risk of CVD was 2.00 (95% CI 1.70-2.37) among PLHIV on ART compared with HIV-uninfected people and 1.52 (95% CI 1.35-1.70) compared with treatment-naïve PLHIV. We estimate the relative risk of CVD associated with protease inhibitor (PI)-, nucleoside reverse transcriptase inhibitor- and nonnucleoside reverse transcriptase inhibitor-based ART to be 1.11 (95% CI 1.05-1.17), 1.05 (95% CI 1.01-1.10) and 1.04 (95% CI 0.99-1.09) per year of exposure, respectively. Not all ART was associated with increased risk; specifically, lopinavir/ritonavir and abacavir were associated with the greater risk and the relative risk of MI for PI-based versus non-PI-based ART was 1.41 (95% CI 1.20-1.65).

CONCLUSION

PLHIV are at increased risk of cardiovascular disease. Although effective in prolonging survival, ART (in particular PI-based regimens) is related to further increased risk of CVD events among people at highest initial absolute risk of cardiovascular disease.

The rate of HIV testing is increasing among men who have sex with men in China

OBJECTIVES

HIV infection is spreading relatively quickly among men who have sex with men (MSM) in China. Accurate knowledge of HIV status is of high importance for public health prevention.

METHODS

We conducted a systematic review of literature published in either English or Chinese to collate available HIV testing data among MSM in China. Linear regression and Spearman's rank correlation were used to study factors associated with HIV testing rates.

RESULTS

Fifty-five eligible articles were identified in this review. The proportion of MSM who had ever been tested for HIV has significantly increased, from 10.8% in 2002 to 51.2% in 2009. In comparison, reported rates of HIV testing in the past 12 months have also significantly increased, from 11.0% in 2003 to 43.7% in 2009.

CONCLUSIONS

Chinese MSM have relatively low HIV testing rates compared with MSM in other settings. It is important to continue to promote HIV testing among MSM in China.

Male circumcision for HIV prevention in Papua New Guinea: a summary of research evidence and recommendations for public health following a national policy forum

In 2005, a clinical trial in South Africa found that circumcision of young men could reduce their risk of acquiring HIV (human immunodeficiency virus) infection by over 60%. In the following year, two more trials in Africa confirmed this finding, leading the World Health Organization to recommend male circumcision as a public health strategy for HIV prevention in high-incidence countries. In order to inform public health policy in Papua New Guinea (PNG), two major research projects were initiated with the goals of investigating the status of penile cutting practices and assessing understandings, acceptability, feasibility and cost-effectiveness of male circumcision for HIV prevention. In addition, behavioural surveillance surveys systematically asked questions on penile cutting practices and an ethnographic literature review informed historical perspectives of penile cutting in PNG. Key findings from these research activities were presented at a National Policy Forum on Male Circumcision for HIV Prevention held in Port Moresby in November 2011. The Forum made three key recommendations: (1) the formation of a joint National Department of HealthlNational AIDS Council Secretariat Policy Committee on male circumcision; (2) the establishment of an integrated harm reduction program; and (3) that future policy on wide-scale roll-out of male circumcision for HIV prevention in PNG be informed by a combination of data from (a) male circumcision intervention pilot programs and (b) research on the potential protective effect of other forms of penile cutting.

Prodrug delivery of novel PTP1B inhibitors to enhance insulin signalling

A growing percentage of the population is resistant to two key hormones - insulin and leptin - as a result of increased obesity, often leading to significant health consequences such as type 2 diabetes. Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of signalling by both of these hormones, so that inhibitors of this enzyme may provide promise for correcting endocrine abnormalities in both diabetes and obesity. As with other tyrosine phosphatases, identification of viable drug candidates targeting PTP1B has been elusive because of the nature of its active site. Beginning with novel phosphotyrosine mimetics, we have designed some of the most potent PTP1B inhibitors. However, their highly acidic structures limit intrinsic permeability and pharmacokinetics. Ester prodrugs of these inhibitors improve their drug-like properties with the goal of delivering these nanomolar inhibitors to the cytoplasm of cells within target tissues. In addition to identifying prodrugs that is able to deliver active drugs into cells to inhibit PTP1B and increase insulin signalling, these compounds were further modified to gain a variety of cleavage properties for targeting activity in vivo. One such prodrug candidate improved insulin sensitivity in ob/ob mice, with lowered fasting blood glucose levels seen in the context of lowered fasting insulin levels following 4 days of intraperitoneal dosing. The results presented in this study highlight the potential for design of orally active drug candidates targeting PTP1B, while also delineating the considerable challenges remaining.

The use of surrogate vascular markers in youth at risk for premature cardiovascular disease

Premature cardiovascular disease (CVD) begins in youth--a crucial period when modification of the disease may have the greatest impact. Failure to diagnose preclinical CVD at this stage misses a major opportunity to prevent the long-term consequences of this disease. An array of surrogate vascular markers (SVMs) are now available that can determine the extent of preclinical vascular injury in the pediatric population. These SVMs include flow-mediated vasodilatation, carotid intima media thickness, arterial stiffness, and biomarkers including high sensitivity C-reactive protein, cell adhesion molecules and methylarginines. We believe that the use of these SVMs will help to develop a better understanding of early pathological vascular changes in youth, facilitate earlier diagnosis of preclinical atherosclerosis and provide an objective measure of the vascular effects of any therapeutic intervention aimed at risk factor modification. Ultimately, our future health will depend on carefully balancing the benefits of early diagnosis and treatment in high-risk youth with the long-term risk of CVD. The application of SVMs in the pediatric population will help us achieve this balance.

Type III secretion, contact-dependent model for the intracellular development of chlamydia

The medically significant genus Chlamydia is a class of obligate intracellular bacterial pathogens that replicate within vacuoles in host eukaryotic cells termed inclusions. Chlamydia's developmental cycle involves two forms; an infectious extracellular form, known as an elementary body (EB), and a non-infectious form, known as the reticulate body (RB), that replicates inside the vacuoles of the host cells. The RB surface is covered in projections that are in intimate contact with the inclusion membrane. Late in the developmental cycle, these reticulate bodies differentiate into the elementary body form. In this paper, we present a hypothesis for the modulation of these developmental events involving the contact-dependent type III secretion (TTS) system. TTS surface projections mediate intimate contact between the RB and the inclusion membrane. Below a certain number of projections, detachment of the RB provides a signal for late differentiation of RB into EB. We use data and develop a mathematical model investigating this hypothesis. If the hypothesis proves to be accurate, then we have shown that increasing the number of inclusions per host cell will increase the number of infectious progeny EB until some optimal number of inclusions. For more inclusions than this optimum, the infectious yield is reduced because of spatial restrictions. We also predict that a reduction in the number of projections on the surface of the RB (and as early as possible during development) will significantly reduce the burst size of infectious EB particles. Many of the results predicted by the model can be tested experimentally and may lead to the identification of potential targets for drug design.

Bicyclic and tricyclic thiophenes as protein tyrosine phosphatase 1B inhibitors

A novel pyridothiophene inhibitor of PTP1B was discovered by rational screening of phosphotyrosine mimics at high micromolar concentrations. The potency of this lead compound has been improved significantly by medicinal chemistry guided by X-ray crystallography and molecular modeling. Excellent consistency has been observed between structure-activity relationships and structural information from PTP1B-inhibitor complexes.

Use of a quantitative gene expression assay based on micro-array techniques and a mathematical model for the investigation of chlamydial generation time

Chlamydia is an important pathogen which possesses a unique developmental cycle. We used real-time PCR technology to measure gene transcript levels in Chlamydia trachomatis strain L2. By measuring 16S rRNA transcript levels, and developing a mathematical model of the chlamydial developmental cycle fitting the data, we predict an average generation time of approximately 2.6 h. Additionally, potentially this modelling also provides the foundation for the application of emerging micro-array technology in which identification of the gene signals that trigger a chlamydial body to start replicating or transform to its infectious form can be made possible.

A model of neutralization of Chlamydia trachomatis based on antibody and host cell aggregation on the elementary body surface

Humoral immunity is that aspect of specific immunity that is mediated by B lymphocytes and involves the neutralizing of pathogens by means of antibodies attaching to the pathogen's binding sites. Antibodies bind to and block ligand sites on the pathogen which prevents these sites from attaching to target cell receptors and so cell entry is inhibited. Many studies investigate the role of humoral immunity for protection against chlamydial challenge and they have shown that neutralization of the chlamydial body requires a large number of attached antibodies. Steric hindrance greatly influences the number of available sites that may be bound, reducing relative occupancy well below 100%. We model steric effects of antibody Fab fragment attachment indicating that they must be taken into consideration to accurately model valency, the number of available binding sites. We derive a partial differential equation for the number of antibody Fabs and host cell receptors that are aggregated to extracellular chlamydial elementary bodies. We consider steric effects in describing the size distribution of aggregates. Our theory is in good agreement with Monte Carlo simulations of binding. We use our theoretical prediction for the valency in a model for the in-host population dynamics of a chlamydial infection and we fit our model to experimental data.

A mathematical model for the investigation of the Th1 immune response to Chlamydia trachomatis

Chlamydia are bacterial pathogens of humans and animals causing the important human diseases trachoma, sexually transmitted chlamydial disease and pneumonia. Of the human chlamydial diseases, sexually transmitted disease caused by Chlamydia trachomatis is a major public health concern. Chlamydia trachomatis replicates intracellularly and is characterised by a complex developmental cycle. Chlamydia is susceptible to humoral and cell-mediated immunity. Here we investigate the Th1 cell-mediated immune response against Chlamydia-infected cells as the response changes over the chlamydial developmental cycle. We suggest a form for the immune response over one developmental cycle by modelling the change in the number of intracellular chlamydial particles and assume peptides are presented in proportion to the number of replicating forms of chlamydial particles. We predict, perhaps non-intuitively, that persistent Chlamydia should be induced and forced not to return to the lytic cycle. We also suggest that extending the length of the time of the lytic cycle will effectively decrease the required efficacy of the Th1 response to eliminate the pathogen. We produce plots of active disease progression, control and clearance for varying levels of Th1 effectiveness.

A Mathematical Model of Continuous HIV Mutations Eluding Immune Defence

We develop a description of HIV mutations based upon a continuum representation of the fitness of the virus, including the interaction of the virus with both specific Th1 lymphocytes as well as cross-reactive cells. This deterministic model allows a straightforward measure of the diversity of viral population and reproduces the observed increase in diversity as the disease progresses in an untreated patient. We use the diversity threshold theory, extending the modelling to track mutations on a continuum. When the diversity threshold is exceeded, the host immune system collapses.

Bradykinin receptor antagonists attenuate neointimal proliferation postangioplasty

Bradykinin has been linked to the development of restenosis in response to vascular injury. We therefore examined the effect of bradykinin on vascular smooth muscle cell growth and neointimal formation in organ culture. Bradykinin stimulated both RNA and DNA synthesis (by 175%) in smooth muscle cells from either porcine or human coronary arteries and increased cell number in a concentration-dependent manner. Both p42/44 mitogen-activated protein kinase (MAPK) and p38 kinase were also activated. Treatment with [Hyp(3),Tyr(Me)(8)]bradykinin, a B(2) receptor agonist, stimulated thymidine incorporation by 146%, whereas B(1)-selective Lys-des-Arg(9)-bradykinin had no effect. Addition of the B(2) antagonist HOE-140 reduced the stimulation by 56%, whereas B(1)-selective des-Arg-HOE-140 had no significant effect. Similarly, HOE-140 attenuated angioplasty-induced neointimal formation in organ culture with an efficacy approaching 100% inhibition. These experiments suggest that bradykinin promotes smooth muscle proliferation after vascular injury, presumably via B(2) receptor-dependent activation of MAPK family pathways, and may explain the negative outcome of angiotensin converting enzyme inhibitor therapy on restenosis in nonrodent models.

Hypothyroxinemia of prematurity: rite of passage or therapeutic necessity?

Hypothyroxinemia is a common finding in premature infants, presumably resulting from an immature hypothalamic-pituitary-thyroid axis. Because dynamic studies of thyroid function in premature infants are normal and the condition resolves spontaneously, HOP has been considered physiologic rather than pathologic. Thus, thyroid hormone supplementation has been assumed to be not required in premature infants. True hypothyroidism of hypothalamic pituitary or thyroid origin, however, does occur in premature as well as in term infants and should be investigated aggressively and treated appropriately. Current studies in premature infants with hypothyroxinemia suggest the following: infants with more than 27 weeks of gestation do not appear to benefit and may, in fact, be harmed by thyroid hormone supplementation; and short-term thyroid hormone supplementation in infants born before 27 weeks of gestation may be important to diminish morbidity and to improve neurodevelopmental outcome.

Angiotensin II receptor antagonists prevent neointimal proliferation in a porcine coronary artery organ culture model

OBJECTIVES

Angiotensin II (AngII) generation in response to vascular injury has long been assumed to influence neointimal proliferation contributing to restenosis. This concept has been supported by evidence that ACE inhibition and AT1 receptor blockade effectively limits restenosis in the rat. On the other hand, ACE inhibition has proven ineffective in clinical trails. The present study examines the response of the porcine coronary artery after angioplasty in vitro and compares the actions of an ACE inhibitor to AngII receptor antagonists.

METHODS AND RESULTS

Captopril, an ACE inhibitor, and the AngII receptor antagonists, losartan and PD123319, were evaluated for their ability to attenuate neointimal proliferation in a porcine organ culture model of coronary restenosis. The neointima was significantly increased by 300% after angioplasty compared to non-angioplasty controls. The AT1 receptor antagonist, losartan, produced a significant reduction in neointimal index at 10(-5) mol/l, while its in vivo metabolite, EXP3174, reduced neointimal proliferation at 10(-6) mol/l. PD123319, a selective antagonist of the AT2 receptor, also restricted neointimal proliferation at 10(-5) mol/l. Treatment with captopril (10(-6) mol/l) increased the neointimal proliferation by approximately 200% after angioplasty.

CONCLUSIONS

Direct blockade of AngII receptors effectively inhibits cell proliferation and restenosis post-angioplasty in vitro. ACE inhibition, exclusive of flow, does not attenuate proliferative restenosis. These data suggest that AngII contributes to neointimal proliferation and validates the concept that receptor antagonists could contribute to the therapeutic management of restenosis.

Growth hormone improves weight velocity and height velocity in prepubertal children with cystic fibrosis

We undertook this study to determine if growth hormone treatment of prepubertal children with cystic fibrosis could improve their height and weight. Nine prepubertal children with cystic fibrosis were treated with human recombinant growth hormone for one year. Results obtained during this year were compared to similar measurements made for each patient for the one year prior to the treatment year. Anthropometric data including: height, height velocity, weight, weight velocity and skin fold thickness were measured at three month intervals. Pulmonary function and skeletal muscle strength were measured at three month intervals. Glucose tolerance was evaluated by HbAlc and by fasting blood glucose and insulin levels every three months. Our results demonstrate that growth hormone treatment resulted in significant improvement in height velocity and height Z scores. Weight increased in all subjects, with a significant increase in weight velocity (year prior to treatment = 1.7+/-1.0 kg/yr, treatment year = 3.8+/-1.6 kg/yr; p=0.03). Measurements of skin fold thickness suggests that lean body mass improved with growth hormone treatment. Pulmonary function improved in all but two patients, whose pulmonary function remained the same and muscle strength improved in all subjects. These results suggest that growth hormone used in prepubertal children with cystic fibrosis can improve height and weight and may improve lean body mass.

FH Tulsa-1 and -2: two unique alleles for familial hypercholesterolemia presenting in an affected two-year-old African-American male

A two-year-old African American boy presented with cutaneous xanthomata and extreme hypercholesterolemia. Subsequent studies revealed that the LDL-cholesterol was 1,001 mg/dl and apoB 507 mg/dl. LDL-receptor activity was almost undetectable, which is compatible with the finding of two newly described defective alleles on exon 4 of the LDL-receptor gene coding for part of the ligand-binding domain. One allele contained a 21 base-pair insertion from codon 200 to 207 whereas the other had a point mutation at codon 207. The rarity of genes for FH reported in individuals of African ancestry is discussed.

How short is too short?

A review of growth parameters should be a routine part of pediatric care. Children and parents need to be helped in understanding normal growth and development. Variations in growth should be explained, and concerns of parents and children openly discussed. Age appropriate educational materials are often helpful. Children with abnormal growth should be referred promptly for definitive diagnosis, selection of treatable candidates, and monitoring.

Lipids and apolipoproteins in growth hormone-deficient children during treatment

The role of growth hormone (GH) in regulating the transport of plasma lipoproteins has not been clearly defined, but past studies suggest that GH may influence cholesterol levels. This protocol was designed to evaluate possible changes in lipid and apolipoprotein status in GH-deficient children and children with neurosecretory dysfunction (NS) before GH therapy and at intervals after GH therapy was started. Twenty children with classic GH deficiency were evaluated, and 28% were hyperlipidemic at the onset of the study. Seven children were evaluated in the NS group, and only one (14%) showed an elevated total cholesterol (TC) greater than 200 mg/dL. The mean TC for all the GH-deficient children was elevated above the normal range, but not for the NS group. The mean apolipoprotein (apo) C-III level and its heparin-precipitated fraction (HP) were also elevated in the GH-deficient group, but only the apo C-III HP was elevated in the NS group. A standard replacement dose of recombinant methionyl GH was used, and therapy had no significant effect on TC or triglyceride (TG) levels. Apo C-III HP, a marker of hypertriglyceridemia, increased after the start of therapy, but no other lipoprotein levels changed significantly in the GH-deficient group. No changes were seen with treatment in the NS group. The longitudinal design of this study allowed demonstration of the later changes in the apolipoproteins and the presence of a distinct subset of patients with both GH deficiency and hypercholesterolemia. This study supports the role of GH in modulating lipid metabolism.

Human growth hormone and Creutzfeldt-Jakob disease

For more than 20 years cadaver-derived human growth hormone (HGH) was used successfully to enhance linear growth in short children. In 1985 the US Food and Drug Administration (FDA) stopped use of the hormone in response to reported deaths due to Creutzfeldt-Jakob (CJD) agent in 3 former HGH recipients. To date, a total of 9 patients have been identified who both received HGH and became infected with CJD agent (7 in the United States, 1 in Britain, and 1 in New Zealand). Circumstances make it likely that HGH contaminated with a slow growing, viral-like particle may have been responsible for these fatalities. In Oklahoma at least 60 children and adolescents previously received HGH and are potentially at risk of developing CJD. It is important that health care providers responsible for the care of these individuals be aware of this fatal illness and remain informed of new developments in the field.

Growth hormone: past, present, and future

Recent progress in the diagnosis and therapy of IGHD illustrates the ever-increasing influence of recombinant DNA research. Recombinant DNA technology has already resulted in the synthesis of therapeutic growth hormone that is both relatively easy to produce and safe. Recombinant DNA probes have also been developed that can clearly diagnose one form of growth hormone deficiency (IGHD-1A) and are approaching identification of other forms. Finally, since they function by direct interaction with the genes, probes will also detect the precise molecular defect(s) causing IGHD. This knowledge potentially could lead to a means of correcting the mutations themselves.

Acute Glycemic Effects of Exercise in Adolescents with Insulin-Dependent Diabetes Mellitus

In brief: The acute effect of exercise on blood glucose was observed on 130 occasions in eight adolescents with insulin-dependent diabetes mellitus. All subjects engaged in 30 minutes of either structured aerobic exercise or unstructured recreational activity. The magnitude of decline in the blood glucose level with exercise corresponded to the preexercise blood glucose value: Higher preexercise values were associated with larger declines, while nonelevated preexercise values were associated with smaller declines. No significant differences in glycemic effect were observed between the two categories of exercise. The authors conclude that in adolescents with moderately well-controlled diabetes, recreational activities can be as effective in lowering elevated blood glucose levels as structured exercise.

Partial deletion 21: case report with biochemical studies and review

An unbalanced translocation of a portion of the long arm of chromosome 21 to the short arm of chromosome 4 resulted in a partial deletion of chromosome 21 (pter----q21.05) and in the loss of the telomere of 4p. The phenotype of the child included asymmetrical facies, microcephaly, short stature, hypotonia, and psychomotor retardation associated with frequent infections. Normal SOD-1 activity in red blood cells and fibroblasts and normal cystathionine beta synthase activity in fibroblasts suggest that these gene loci are distal to 21q21.05.

Improved glycemic control after supervised 8-wk exercise program in insulin-dependent diabetic adolescents

Eight insulin-dependent adolescents (4 boys, 4 girls) participated in an 8-wk program of supervised exercise, and 8 matched controls were encouraged to exercise on their own without supervision. All 16 subjects were asked to follow a standard ADA diet plan, kept a self-reported log of caloric intake, and met with a dietitian weekly to review their diets. Exercise for the supervised subjects was scheduled between the routine afternoon snack and the evening meal, and subjects were asked not to consume additional food on exercise days. After the 8-wk program, glycemic control, as measured by glycosylated serum albumin and blood glucose values (but not by glycosylated hemoglobin), improved in the supervised-exercise group despite reduced daily insulin dosage. Cardiorespiratory fitness, as measured by voluntary maximum treadmill time (Bruce protocol) and submaximal exercise heart rates, also improved. No changes were observed in the unsupervised control group.

Umbilical artery catheterization: a potential cause of refractory hypoglycemia

Two infants with persistent, symptomatic hypoglycemia are reported. Both were thought to have iatrogenic hyperinsulinism due to a malpositioned umbilical artery catheter. Repositioning of the catheter to avoid direct infusion into the arterial blood supply to the pancreas resulted in prompt cessation of hypoglycemia.

Compliance with blood glucose monitoring in children with type 1 diabetes mellitus

Compliance with blood glucose monitoring was studied in 18 children with type 1 diabetes. Using specially equipped blood glucose reflectance meters, children monitored their blood glucose levels, with and without knowledge of the meter's memory capability. Poor compliance, as exhibited by fabricated test results (40%) and failure to record test results (18%), occurred in a significant proportion of children. Further research is needed to explore reasons for such behavior and to suggest strategies for improving compliance.