Protein tyrosine phosphatase 1B inhibitors for the treatment of type 2 diabetes and obesity: recent advances

This review outlines the physiology of protein tyrosine phosphatase 1B (PTP1B) and its potential involvement in the states of insulin resistance that characterizes both obesity and type 2 diabetes. The primary focus of this review is upon the elucidation of the role and control of PTP1B enzyme activity in obesity and type 2 diabetes. Furthermore, since selectivity and cell permeability are the two most important requirements for the development of successful PTP1B inhibitors, recent progress in finding compounds meeting these criteria are discussed.     

A novel telomerase template antagonist (GRN163) as a potential anticancer agent

Telomerase, the enzyme responsible for proliferative immortality, is expressed in essentially all cancer cells, but not in most normal human cells. Thus, specific telomerase inhibition is potentially a universal anticancer therapy with few side effects. We designed N3'-->P5' thio-phosphoramidate (NPS) oligonucleotides as telomerase template antagonists and found that their ability to form stable duplexes with the telomerase RNA subunit was the key factor for antitelomerase activity. In biochemical assays 11-13-mer NPS oligonucleotides demonstrated sequence- and dose-dependent inhibition of telomerase with IC(50) values <1 nM. Optimization of the sequence, length, and bioavailability resulted in the selection of a 13-mer NPS oligonucleotide, GRN163, as a drug development candidate. GRN163 inhibited telomerase in a cell-free assay at 45 +/- 7 pM, and in various tumor cell lines at approximately 1 nM and approximately 0.3-1.0 micro M in the presence and absence of carriers, respectively. GRN163 was competitive with telomeric primer binding, primarily because of hybridization to human telomerase RNA (hTR) component. Tumor cells treated with GRN163 in culture underwent telomere shortening, followed by cellular senescence or apoptosis after a period of time that generally correlated with initial telomere length. In a flank DU145 (prostate cancer) xenograft model, parenterally administered GRN163 caused suppression of tumor growth in the absence of gross toxicity. These data demonstrate that GRN163 has significant potential for additional development as an anticancer agent.     

How long should telomeres be?

What began as a study of the "end-replication problem" took on a new dimension as it became clear that telomeres are a "molecular clock" of replication in human somatic cells. Here we review the biology of telomeres in vitro and in vivo, in mice and humans. We suggest that, in humans, telomeres are involved in the biology of aging and pathobiology of disorders of aging, including cancer and cardiovascular disease. We also propose that the underlying dynamics of telomere biology is in line with broad principles of evolutionary theories.     

The Harvard Twin Study of Substance Abuse: what we have learned

The Harvard Twin Study of Substance Abuse was carried out with the members of the Vietnam Era Twin (VET) Registry. The VET Registry comprises over 8000 male twins who served in the United States military between 1965 and 1975 and were subsequently interviewed regarding their use of licit and illicit substances, as well as various types of psychopathology. Our research has demonstrated significant influences by genetic, shared environmental, and unique environmental factors on the abuse of illicit substances. Multivariate analyses have indicated that the co-occurrence of abuse of various types of illicit drugs reflects a common vulnerability, influenced by both genetic and environmental factors, that cuts across all categories of illicit drugs. We have also demonstrated that some drugs have unique determinants, both genetic and environmental, that are not shared with other drugs. In part, the genetic influence on marijuana abuse is mediated by genetic influence on subjective effects in response to the drug. The determinants of transitions from one stage of drug use to another differ depending on which drug or which transition is examined. We determined significant genetic influences on several aspects of nicotine and alcohol use separately, as well as genetic influences shared by both substances. We found that the co-occurrence of illicit drug abuse and major depression is due to unique environmental influences. The phenotypic association between symptoms of conduct disorder and alcohol and marijuana dependence is due largely to shared environmental influences. Our results, thus far, indicate a complex pattern of genetic and environmental influences on substance use and abuse.     

A primary school outbreak of pharyngoconjunctival fever caused by adenovirus type 3

High rates of absenteeism in a North Queensland primary school, due to eye irritation, fever, headache, and stomach pain, were reported to the Tropical Public Health Unit in October 2000. Subsequent investigation demonstrated that the symptoms were due to adenovirus infection. Symptoms were consistent with a diagnosis of pharyngoconjunctival fever. At the height of the outbreak, about 40 per cent of students were absent. There was a strong association between the development of symptoms, and having been swimming on a recent school camp. Adenovirus could not be isolated from swimming pool water from the resort where the camp had been held. However, when inspected the swimming pool was not adequately chlorinated or maintained. It is probable that adenovirus infection was transmitted via swimming pool water at the school camp, and the outbreak might have been avoided by higher standards of swimming pool maintenance.     

Regulation by fibrinogen and its products of intercellular adhesion molecule-1 expression in human saphenous vein endothelial cells

It has been reported that fibrinogen may act as a bridging ligand, binding to intercellular adhesion molecule-1 (ICAM-1) on human umbilical vein endothelial cells and to Mac-1 on THP-1 cells (a monocytic cell line) to increase adhesion. In this study, we investigated whether fibrinogen altered the expression of ICAM-1 and, thus, increased the adhesion of THP-1 cells to cultured human saphenous vein endothelial cells (HSVECs). Incubation of HSVECs with 0.3 to 4 micromol/L fibrinogen caused a time- and concentration-dependent increase in ICAM-1, as determined by ELISA. The 4- to 5-fold increase in ICAM-1 protein concentration in HSVECs stimulated by 4 micromol/L fibrinogen for 6 hours was concomitant with a 4- to 5-fold increase in ICAM-1 mRNA. This fibrinogen-stimulated ICAM-1 upregulation was associated with a 2-fold increase in THP-1 cell adhesion to HSVECs. The fibrinogen-derived peptide Bbeta15-42 bound to HSVECs (K(d) 0.18 micromol/L). Preincubation of HSVECs with Bbeta15-42, a neutralizing antibody to urokinase plasminogen activator (uPA), or the F(ab)(1) fragment of a monoclonal antibody to vascular endothelial cadherin significantly attenuated the increase in ICAM-1 stimulated by fibrinogen. Capillary electrophoretic analysis indicated that anti-uPA prevented the release of any fibrinopeptide B (Bbeta1-14) in cultures of HSVECs incubated with 4 micromol/L fibrinogen for 6 hours. Moreover, incubation of HSVECs with either fibrin monomer (1 micromol/L) or monoclonal antibodies to vascular endothelial cadherin (25 microg/mL) increased ICAM-1 protein concentration 3- to 4-fold. These findings indicate that cleavage of fibrinopeptide B from fibrinogen by endothelial uPA permits the exposed Bbeta15-42 sequence of fibrinogen to bind to vascular endothelial cadherin on HSVECs and to upregulate the expression of ICAM-1.     

Combination chemotherapy for non-Hodgkin lymphomas: a ten year follow-up study.

In 1968 the Cancer and Acute Leukemia Group B (CALGB) demonstrated optimal control of disseminated non-Hodgkin lymphomas (NHL) with vincristine-prednisone induction followed by cyclophosphamide maintenance. A study was then begun to determine whether four drugs in combination or sequence could achieve greater control. NHL patients at each participating CALGB institution were randomly assigned to one of three regimens:I) Cyclic vincristine-streptonigrin alternating every 2 weeks with cyclophosphamide-prednisone up to 155 days; II) Sequential treatment with the same 4 drugs taken singly up to 182 days; and III) Vincristine-prednisone induction for 6 weeks followed by cyclophosphamide maintenance. Results are now reported after a 10 year follow-up period. The 203 evaluable patients are those on whom Rappaport histopathologic classification was available. Frequency of complete-response did not differ significantly among the three regimens: I) 38%; II) 30%; and III) 45%. Remission durations were significantly longer among patients receiving maintenance therapy. After ten years, two patients from Regimen I, one from Regimen II, and five from Regimen III remain alive and well. It was concluded that neither of the four-drug regimens conferred a significant advantage in terms of response rate or survival time over the standard treatment.