A selective human beta3 adrenergic receptor agonist increases metabolic rate in rhesus monkeys

Activation of beta3 adrenergic receptors on the surface of adipocytes leads to increases in intracellular cAMP and stimulation of lipolysis. In brown adipose tissue, this serves to up-regulate and activate the mitochondrial uncoupling protein 1, which mediates a proton conductance pathway that uncouples oxidative phosphorylation, leading to a net increase in energy expenditure. While chronic treatment with beta3 agonists in nonprimate species leads to uncoupling protein 1 up-regulation and weight loss, the relevance of this mechanism to energy metabolism in primates, which have much lower levels of brown adipose tissue, has been questioned. With the discovery of L-755,507, a potent and selective partial agonist for both human and rhesus beta3 receptors, we now demonstrate that acute exposure of rhesus monkeys to a beta3 agonist elicits lipolysis and metabolic rate elevation, and that chronic exposure increases uncoupling protein 1 expression in rhesus brown adipose tissue. These data suggest a role for beta3 agonists in the treatment of human obesity.     

The treatment of basal cell carcinoma patients by dermatologists in Netherland

OBJECTIVE: To determine the policy of dermatologists practising in the Netherlands in the treatment of basal cell carcinoma. DESIGN: Written enquiry. SETTING: Catharina Hospital, Eindhoven, the Netherlands. METHOD: All 293 dermatologists practising in the Netherlands were sent a questionnaire in May 1996 containing 15 questions about diagnosis and treatment of basal cell carcinoma. RESULTS: Eighteen forms dropped off because of termination of the practice or joint completion in group practices. The response was 76% (208/275). The diagnosis was made usually on the basis of histological examination (71% of the respondents; 84% in a tumour recurrence). Excision was the preferred treatment for all subtypes of basal cell carcinoma; second choices were cryosurgery or curettage/electrocoagulation. Roentgen contact therapy has been practically abandoned. New methods such as photodynamic therapy and immunotherapy are being used only sporadically on an experimental basis. Most dermatologists regarded tumour recurrences as a bigger problem than primary tumours. They attempt to reduce the percentage of recurrences by giving advice about risk factors (sunlight). CONCLUSION: Too little use is being made of diagnostic biopsy to enable an optimal choice of therapy of basal cell carcinomas, especially in cases of recurrence tumours.     

Molecular phylogeny of Fv1

Alleles at the Fv1 gene of inbred mice confer resistance to infection and spread of vertically or horizontally transmitted murine leukemia viruses (MuLV). The nucleotide sequence of Fv1 bears similarity to the gag of a human endogenous retrovirus, HERV-L, but is more closely related to the gag-coding sequence of a newly described class of HERV-L-related mouse endogenous retroviruses designated MuERV-L. Both observations suggest an origin of Fv1 from endogenous gag sequences. The molecular definition of Fv1 provided an opportunity to determine the phylogeny of the gene among wild mice and its relation to MuERV-L. PCR primers, chosen to include most of the coding region of Fv1 for both the n and b alleles, were used to amplify sequences from animals of the genus Mus, which were then sequenced. Closely related products were obtained from almost all animals examined that evolved after the separation from Rattus, in which the homologous gene was shown to be absent. A phylogenetic tree generated with Fv1 sequence data differs noticeably from that developed with sequence data from other genes. In addition, non-synonymous changes were found to be present twice as frequently as synonymous changes, a fact that departs from the standard behavior of a structural gene. These observations suggest that the Fv1 gene may have been subjected to possible horizontal transfers as well as to positive Darwinian selection.     

Speciation of arsenic metabolites in the urine of occupational workers and experimental rats using an optimised hydride cold-trapping method

A hydride cold-trapping technique was developed and optimised for the measurement of urinary arsenic metabolites. The analytical precision of the method was found to be 6.1, 4.0 and 4.8% (n = 5) for inorganic arsenic (ASi), monomethylarsonate (MMA) and dimethylarsinate (DMA), respectively, with recoveries close to 100%. The detection limits were 1.0, 1.3 and 3 ng for ASi, MMA and DMA, respectively. The method was then used to analyse urine samples obtained from three groups of workers for occupational exposure in three companies where copper chrome arsenate was used for timber treatment. The results were compared with those for a normal control group of laboratory workers. Arsenic and its metabolites were also measured in experimental rats given 5 mg As kg-1 body mass by oral gavage in the form of sodium arsenite, calcium arsenite or sodium arsenate. Occupational workers showed a significantly higher excretion of ASi. Up to two fold increases of urinary ASi excretion in rats compared with control rats were also observed in animals dosed with various forms of arsenicals. The method is suitable for the measurement of arsenic metabolites in urine of both humans and experimental animals.     

The Diabetes in Early Pregnancy Study: beta-hydroxybutyrate levels in type 1 diabetic pregnancy compared with normal pregnancy. NICHD-Diabetes in Early Pregnancy Study Group (DIEP). National Institute of Child Health and Development

OBJECTIVE: The objective was to assess relationships between beta-hydroxybutyrate (beta-OHB) level and pregnancy outcome in human pregnancy in light of the fact that high levels of beta-OHB cause malformations and growth retardation in in vitro studies. RESEARCH DESIGN AND METHODS: We analyzed beta-OHB in prospectively collected specimens from the National Institute of Child Health and Human Development-Diabetes in Early Pregnancy Study, in gestational weeks 6-12 in diabetic (n = 204-239) and nondiabetic (n = 316-332) pregnant women. RESULTS: Levels of beta-OHB in diabetic women were 2.5-fold higher than in nondiabetic pregnant women at 6 weeks' gestation and declined to 1.6-fold above nondiabetic women by 12 weeks' gestation (P < 0.0001 at all times). beta-OHB was positively correlated with glucose levels (P < 0.0001) in diabetic mothers, probably reflecting degree of diabetic control. beta-OHB correlated inversely with glucose (P < 0.0003) (gestational week 6 only) in nondiabetic mothers, possibly reflecting caloric intake. beta-OHB tended to be lower (not higher) in diabetic and nondiabetic mothers with malformed infants or pregnancy losses, but the difference was not statistically significant. beta-OHB in diabetic mothers at 8, 10, and 12 weeks correlated inversely with birth weight (P = 0.004-0.02), even after adjusting for maternal glucose levels. beta-OHB levels were also generally lower in diabetic mothers of macrosomic infants, and week 12 ultrasound crown-rump measurements were inversely related to beta-OHB levels. CONCLUSIONS: The lst trimester beta-OHB is significantly higher in diabetic than nondiabetic pregnant women. In both groups, beta-OHB tended to be lower, not higher, in mothers who had a malformed infant or pregnancy loss. beta-OHB was inversely related to crown-rump length and birth weight. The modest beta-OHB elevation in the 1st trimester of reasonably well-controlled diabetic pregnancy is not associated with malformations, probably because beta-OHB levels causing malformations in embryo culture models are 20- to 40-fold higher. The mechanism of the beta-OHB association with impaired fetal growth is unknown.     

Ehlers-Danlos syndrome type II in pregnancy

The Allen test was performed by four physician examiners on 200 hands of healthy volunteers. Positive results were found in 5.5% of hands. There was not a single case in which all four observers agreed. Considerable inter-observer disagreement is associated with the Allen test.     

Guidelines and practice of evidence based medicine

This is a review paper with pedagogic goals in essence. The concept of guidelines is defined and the function and types of guidelines described. Different types of guidelines, such as normative, methodological and practice-motivated, are considered. The most common methods for the drafting of guidelines are presented. The difference between evidence-based guidelines and consensus-based guidelines is established and the importance of grading the strength of recommendations in guidelines, on basis of the validity of the evidence, is stressed. Finally, an update of the role of guidelines in the practice of EBM is put forward.     

Disposition kinetics of cobalt mesoporphyrin in mouse, rat, monkey and dog

1. Radiometric and UV analyses indicated > 95% unchanged cobalt mesoporphyrin (CoMP) in plasma after i.v. or i.m. administration. Blood clearance of CoMP is < 2% of hepatic blood flow in mouse and rat, and < 0.5% of hepatic blood flow in monkey and dog. CoMP elimination t1/2 ranged from 3.1 to 9.9 days in animals after i.v. administration. 2. CoMP is highly (> 99.5%) bound to plasma proteins, but has low affinity for blood cells (Kp < 0.15). The volume of CoMP distribution (Vss < 0.91/kg) is reflective of a distribution to total body water following i.v. administration to mouse, rat, monkey and dog. 3. [14C]CoMP reached highest levels in rat tissue between 1 and 4 days following i.m. injection. Liver, kidney cortex, lymph node, adrenal and spleen demonstrated greatest uptake of radiolabel. Concentration in tissues was readily detectable at 60 days post-dose. 4. CoMP was slowly absorbed after i.m. administration showing dose-dependent pharmacokinetics. The major route of radiolabel elimination was faecal excretion (54% of dose) in rat after an i.m. dose of [14C]CoMP. Approximately 1% of the 14C dose was recovered in the urine over 7 days post-dose. 5. As a polar metalloporphyrin, CoMP has low clearance, restricted tissue distribution and long elimination t1/2 in the laboratory animals.     

Exploring the active site of herpes simplex virus type-1 thymidine kinase by X-ray crystallography of complexes with aciclovir and other ligands

Antiherpes therapies are principally targeted at viral thymidine kinases and utilize nucleoside analogs, the triphosphates of which are inhibitors of viral DNA polymerase or result in toxic effects when incorporated into DNA. The most frequently used drug, aciclovir (Zovirax), is a relatively poor substrate for thymidine kinase and high-resolution structural information on drugs and other molecules binding to the target is therefore important for the design of novel and more potent chemotherapy, both in antiherpes treatment and in gene therapy systems where thymidine kinase is expressed. Here, we report for the first time the binary complexes of HSV-1 thymidine kinase (TK) with the drug molecules aciclovir and penciclovir, determined by X-ray crystallography at 2.37 A resolution. Moreover, from new data at 2.14 A resolution, the refined structure of the complex of TK with its substrate deoxythymidine (R = 0.209 for 96% of all data) now reveals much detail concerning substrate and solvent interactions with the enzyme. Structures of the complexes of TK with four halogen-containing substrate analogs have also been solved, to resolutions better than 2.4 A. The various TK inhibitors broadly fall into three groups which together probe the space of the enzyme active site in a manner that no one molecule does alone, so giving a composite picture of active site interactions that can be exploited in the design of novel compounds.