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.