On the Nature of the Compact Star in 4U 1728-34

The discovery of kilohertz quasi-periodic oscillations (kHz QPOs) in low-mass X-ray binaries (LMXBs) with the Rossi X-Ray Timing Explorer has stimulated extensive studies of these sources. Recently, Osherovich & Titarchuk suggested a new model for kHz QPOs and the related correlations between kHz QPOs and low-frequency features in LMXBs. Here we use their results to study the mass-radius relation for the atoll source 4U 1728-34. We find that, if this model is correct, 4U 1728-34 is possibly a strange star rather than a neutron star.

Gamma-glutamylcysteine synthetase activity in human lung epithelial (A549) cells: factors influencing its measurement

Despite the central role of gamma-glutamylcysteine synthetase (gammaGCS) in lung antioxidant defenses, the limited studies of the activity of this enzyme in respiratory cells have produced variable results. This study has examined the factors, which may influence the measurement of gammaGCS activity in cultured human lung epithelial cells (A549). Although a source of potential error, gammaGCS activity in A549 cell extracts did not vary significantly when appropriately assayed by three different methods or after removal of the endogenous inhibitor, glutathione (GSH). However, gammaGCS activity did increase significantly during the early stages of cell proliferation (3.50 +/- 0.31 vs. 2.35 +/- 0.16 nmol/min/10(6) cells for baseline, p < .001) and thereafter returned to baseline levels during the later stages of cell growth. Variations in initial plating density also significantly altered gammaGCS activity (3.11 +/- 0.14 vs. 4.04 +/- 0.50 nmol/min/10(6) cells, at 0.25 x 10(5) and 0.58 x 10(5) cells/cm2, respectively, p < .001) and GSH content (45.43 +/- 4.43 vs. 63.64 +/- 3.28 nmol/10(6) cells at 0.25 x 10(5) and 0.58 x 10(5) cells/cm2, respectively, p < .001) during the early stages of cell proliferation. In addition, gammaGCS activity and GSH content were highest in A549 cells grown in medium containing cystine as the predominant sulfur-containing amino acid. These results suggest that gammaGCS activity of A549 cells is strongly dependent on initial plating density, stage of cell growth and sulfur amino acid content of the medium and may account for some of the variation in values reported by different investigators. Whether gammaGCS has an important role in the early phase of cell proliferation needs further investigation.

Effect of all-trans-retinoic acid on integrin receptors of human cervical cancer (SiHa) cells

Cell surface receptors have been the subject of intensive investigations over the past few decades. One very important group of receptors on the cell surface is the "integrin" receptors which bind to extracellular matrix (ECM) proteins. Because of integrin's importance in cellular growth, development, and morphology the role of integrin receptors in cellular transformation, malignant growth, and metastasis has received wide attention. In this article we report on the effect of all-trans-retinoic acid (ATRA) on (a) the integrin family of cell surface receptors, (b) collagenase enzyme activity, and (c) invasive potential in human cervical cancer (SiHa) cells. A comparative cell adhesion assay clearly showed that ATRA affects the cell surface integrin receptors against different ECM proteins in a dose- and time-dependent manner. The binding of SiHa cells to ECM proteins (fibronectin, vitronectin, laminin, collagen IV) was drastically reduced when cells were treated with ATRA at 10 microM for 96 h in culture. Interestingly, when ATRA-treated (10 microM, 96 h) SiHa cells were allowed to grow for 15 days in ATRA-free complete medium the binding of SiHa cells to fibronectin and vitronectin was inhibited, even after 15 days of drug withdrawal, whereas cell adhesion to laminin and collagen IV returned to normal within 3-7 days. The comparative immunoprecipitation of two cell surface integrin receptors (alpha5beta1 and alphavbeta3) shows the effect of ATRA on the expression of alpha5, alphav, and beta1 subunits. In ATRA-treated SiHa cells the cell surface expression of the alphav subunit (in alphavbeta3 receptor) is much less than in untreated SiHa cells. In the case of the alpha5beta1 integrin receptor ATRA treatment caused a significant reduction in the expression of both alpha5 and beta1 subunits on the cell surface. Comparative zymography clearly demonstrated the inhibitory effect of ATRA on collagenase enzyme activity. Interestingly, the effect was irreversible, even after 15 days of culture in ATRA-free medium. The assay of the invasive potential of ATRA-treated and untreated SiHa cells in Boyden's invasion chamber demonstrated that ATRA treatment (10 microM, 96 h) inhibits the invasive potential of SiHa cells. The effect was not reversible even after 15 days of culture in ATRA-free medium. In conclusion, our observations indicate that ATRA has an inhibitory effect on the expression of SiHa cell surface integrin receptors and collagenase enzyme activity. The effect of ATRA on cell surface integrin receptors and collagenase enzyme activity may affect the invasive potential of SiHa cells.

Antimutagenic effects of centchroman--a contraceptive and a candidate drug for breast cancer in multiple mutational assays

Centchroman (CC), a non-steroidal oral contraceptive and a candidate drug for breast cancer, has been reported to exhibit partial to complete remission of lesions in 40.5% of breast cancer patients. The potent anti-oestrogenic activity, negligible side-effects and anti-breast cancer activity of CC prompted us to evaluate the antimutagenic effects of this compound in a bacterial mutagenicity assay and CHO/HPRT and AS52/GPT mutation assays in vitro and in vivo in female Swiss albino mice as measured by both sister chromatid exchange (SCE) and chromosome aberrations (CA) against three known positive mutagen compounds, dimethylbenz[a]anthracene (DMBA), cyclophosphamide (CP) and mitomycin C (MMC). Antimutagenicity assays in Salmonella strains TA97a, TA100, TA98 and TA102 were carried out against commonly used known positive mutagens, sodium azide, 4-nitro-o-phenylenediamine, cumine hydroperoxide, 2-aminofluorene and danthron. A significantly reduced number of bacterial histidine revertant colonies was observed in the plates treated with 0.1, 1, 5 and 10 microg/plate CC and a positive compound when compared with bacterial plates treated with the respective positive compound alone. Ethyl methanesulfonate (EMS), a commonly used positive mutagen for CHO/HPRT and AS52/GPT gene mutation assays, was used for antimutagenicity assay in these cells. CC exhibited protective effects against the mutagenicity of EMS in these two mammalian cell mutation assays, CHO/HPRT and AS52/GPT. In the in vivo studies, pretreatment with CC reduced DMBA-induced SCE and CA and CP- and MMC-induced CA when compared with the group treated only with the positive compounds. These results indicate that CC can reduce the mutagenic effects of known genotoxic compounds.

Crystal structure of the ectodomain of human transferrin receptor

The transferrin receptor (TfR) undergoes multiple rounds of clathrin-mediated endocytosis and reemergence at the cell surface, importing iron-loaded transferrin (Tf) and recycling apotransferrin after discharge of iron in the endosome. The crystal structure of the dimeric ectodomain of the human TfR, determined here to 3.2 angstroms resolution, reveals a three-domain subunit. One domain closely resembles carboxy- and aminopeptidases, and features of membrane glutamate carboxypeptidase can be deduced from the TfR structure. A model is proposed for Tf binding to the receptor.

DNA polymerase-associated lectin (DPAL) and its binding to the galactose-containing glycoconjugate of the replication complex

The highly purified DNA Pol-alpha from rat prostate tumor (PA-3) and human neuroblastoma (IMR-32) cells appeared to be inhibited by Ricin (RCA-II), and Con-A. Loss of activity (40 to 60%) of a specific form of DNA polymerase from IMR-32 was observed when the cells were treated with tunicamycin [Bhattacharya, P. and Basu, S. (1982) Proc. Natl. Acad. Sci., USA 79:1488-1492]. Binding of ConA and RCA to human recombinant DNA polymerase-alpha showed a specific labile site in the N-terminus [Hsi et al.. (1990) Nucleic Acid Res. 18:6231-6237]. The catalytic polypeptide, DNA polymerase-alpha of eukaryotic origin, was isolated from developing tissues or cultured cells as a family of 180 to 120 kDa polypeptides, perhaps derived from a single primary structure. Immunoblot analysis with a monoclonal antibody (SJK-237-71) indicated that the lower molecular weight polypeptides resulted from either proteolytic cleavage of post-translational modification after specific cleavages. Present results suggest DNA polymerase-alpha from embryonic chicken brain (ECB) contains an alpha-galactose-binding subunit which may be involved in developmental regulation of the enzyme. It was shown before that the catalytic subunit of DNA polymerase-alpha reduces from 186 kDa in 11-day-old ECB to 120 kDa in 19-day-old ECB [Ray, S. et al. Cell Growth and Differentiation 2:567-573] by the treatment with methyl-alpha-galactose. The low molecular weight DNA polymerase activity (120 kDa) can be reconstituted to high molecular weight (Mr = 186 kDa) with an alpha-galactose binding, 56kDa lectin-like protein. Polyclonal antibodies raised against the purified lectin were able to precipitate DNA. Pol-alpha as determined by immunostaining with the polymerase-alpha-specific monoclonal antibody SJK 132-20, suggesting this is a DNA polymerase associated-lectin (DPAL). RCA-II and GS-I-Sepharose 4B chromatographies resulted in significant purification of DNA-alpha and a complete separation of polymerase complex and primase.

Anticlastogenic effects of centchroman and its enantiomers in Swiss albino mice. I. Acute study and their comparison with tamoxifen

Centchroman (CC), a non steroidal oral contraceptive and a candidate drug for breast cancer, has been reported to exhibit partial to complete remission of lesions in 40.5% of breast cancer patients. Recently, we have reported the antimutagenic effects of CC in multiple mutational assays. The potent antioestrogenic activity, negligible side effects, anti-breast cancer activity and antimutagenic effects of CC prompted us to evaluate the anticlastogenic effects of CC and two of its enantiomers. i.e. D-centchroman (DC) and L-centchroman (LC) in the acute in vivo studies in female Swiss albino mice as measured by chromosome aberrations (CA) and sister chromatid exchange (SCE) assays against two known positive mutagen compounds, i.e. dimethylbenz[a]anthracene (DMBA) and cyclophosphamide (CP). The results of anti-mutagenicity assays of CC and its enantiomers have been compared to the known breast cancer drug tamoxifen (TM). CC and LC reduced both DMBA and CP induced CA when compared with the group treated with only DMBA and CP. DC did not reduce the DMBA-induced CA when compared with the DMBA-treated group alone. It reduces only the CP induced CA. TM also reduces both DMBA and CP induced CA when compared with group received only DMBA or CP. SCE were carried out only for LC. A weak but significant decrease in SCE was observed in both LC plus DMBA- and LC plus CP-treated groups when compared with respective positive controls alone. Thus the overall results indicate that both CC and LC are more effective in reducing the genotoxic effects of DMBA and CP than DC.

Mechanistic studies to evaluate the enhanced antiproliferation of human keratinocytes by 1alpha,25-dihydroxyvitamin D(3)-3-bromoacetate, a covalent modifier of vitamin D receptor, compared to 1alpha,25-dihydroxyvitamin D(3)

1alpha,25-Dihydroxyvitamin D(3)-3-bromoacetate (1, 25(OH)(2)D(3)-3-BE), an affinity labeling analog of 1alpha, 25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), displayed stronger antiproliferative activities than 1,25(OH)(2)D(3) at 10(-10)-10(-6) M dose levels in cultured human keratinocytes (CHK). Additionally, preincubation of the cells with 10(-6) M 1,25(OH)(2)D(3), followed by treatment with various doses of 1,25(OH)(2)D(3)-3-BE, resulted in a significantly stronger antiproliferative activity by the mixture than individual reagents at every dose level. To search for a mechanism of this observation, we determined that [(14)C]1, 25(OH)(2)D(3)-3-BE covalently labeled human recombinant 1alpha, 25-dihydroxyvitamin D(3) receptor (reVDR) swiftly (<1 min) with a 1:1 stoichiometry and induced conformational changes (in VDR) that are different from 1,25(OH)(2)D(3), by limited tryptic digestion. Furthermore, a protein band, corresponding to reVDR, was specifically labeled by [(14)C]1,25(OH)(2)D(3)-3-BE in CHK extract, indicating that VDR is the main target of [(14)C]1, 25(OH)(2)D(3)-3-BE. The above-mentioned observations suggest that a rapid covalent labeling of VDR in CHK might alter the interaction between the holo-VDR and 1,25(OH)(2)D(3)-controlled genes. Furthermore, we observed that 1,25(OH)(2)D(3)-3-BE significantly decreased the binding of VDR to human osteocalcin vitamin D responsive element (hOCVDRE), as well as the dissociation rate of VDR from hOCVDRE, compared with 1,25(OH)(2)D(3) in COS-1 cells, transiently transfected with a VDR construct. Additionally, 1, 25(OH)(2)D(3)-3-BE was found to be more potent in inducing 1alpha, 25-dihydroxyvitamin D(3)-24-hydroxylase (24-OHase) promoter activity and mRNA expression in keratinocytes. The accumulation of 24-OHase message was also prolonged by the analog. Collectively these results indicated that rapid covalent labeling of VDR in keratinocytes (by 1, 25(OH)(2)D(3)-3-BE) might result in the conversion of apo-VDR to a holo-form, with a conformation that is different from that of the 1, 25(OH)(2)D(3)-VDR complex. This resulted in an enhanced stability of the 1,25(OH)(2)D(3)-3-BE/VDR-VDRE complex and contributed to the amplified antiproliferative effect of 1,25(OH)(2)D(3)-3-BE in keratinocytes.

Comparative antimutagenic effects of D- and L-centchroman and their comparison with tamoxifen in Salmonella assay

Centchroman (CC)--a contraceptive and a candidate drug for breast cancer has been developed by the Central Drug Research Institute. It has been successfully marketed as a contraceptive for last several years. CC has also been reported to exhibit partial to complete remission of lesions in 40.5% breast cancer patients. Recently, we have reported the antimutagenic effects of CC in Ames Salmonella assay and in vivo and in vitro mammalian cells in multiple mutational assay. The potent antimutagenic activity of CC and its anti-breast cancer activity prompted us to evaluate the antimutagenic effects of its enantiomers, i.e., D-centchroman (DC) and L-centchroman (LC) in the Ames Salmonella strains TA97a, TA98, TA100 and TA102 against known bacterial mutagens. Attempts have also been made to compare the results of antimutagenicity assays of CC and its enantiomers with the known breast cancer drug tamoxifen (TM). The main objective was to identify the best suitable form of CC having antimutagenic effects with anticancer profile similar to TM, would replace the latter for toxicity reasons. When mutagenicity assays were carried out with these compounds as expected like CC, none of these enantiomers or TM showed any mutagenic effects in these Salmonella strains. In the antimutagenicity assay a significantly reduced number of bacterial histidine revertant colonies were observed when positive compounds were co-incubated with certain concentrations of LC compared with bacterial plates treated with respective positive compound. This was observed in some concentrations in all the four strains in both plate incorporation and preincubation tests. The protective effects of LC in preincubation tests were slightly more than in plate incorporation tests. Both the DC and TM showed protective effects only in certain concentrations in some strains in either plate or preincubation tests. Thus the above results indicate that LC showed more protective effects in Salmonella strains TA97a, TA98, TA100 and TA102 than either DC or TM.

Use of a low-literacy patient education tool to enhance pneumococcal vaccination rates. A randomized controlled trial

CONTEXT

Pneumococcal immunization rates for elderly and high-risk patients are only one third to one half the target rate of 60% established by the US Public Health Service. Limited or marginal literacy, which affects nearly 100 million Americans, especially the elderly, may contribute to these low rates of immunization.

OBJECTIVE

To determine whether the use of a simple, low-literacy educational tool enhances patient-physician dialogue about pneumococcal vaccination and increases rates of immunization.

DESIGN

A randomized controlled trial conducted between May and June of 1998.

SETTING

Ambulatory care clinic of a 900-bed public teaching hospital serving a predominantly indigent, low-literate, African American, inner-city population.

PARTICIPANTS

Of 433 patients who presented for routine primary care, had vaccine indications (age > or =65 years or chronic disease), and had not been previously vaccinated, 221 were randomly assigned to the intervention group and 212 to the control group. Of the total patient population (mean age, 63 years), 280 (64.7%) had less than a high school education, 401 (92.6%) were African American, and 300 (69.3%) were female.

INTERVENTION

One-page, low-literacy (below fifth-grade level) educational handout encouraging patients to "ask your doctor about the pneumonia shot" vs a control group (1 -page, low-literacy educational handout conveying information about nutrition).

MAIN OUTCOME MEASURES

Vaccination rates (documented by chart audit) of patients who received pneumococcal vaccination and rates of patients who self-reported having discussed vaccination with their physicians.

RESULTS

Patients in the intervention group were 4 times more likely to have discussed the pneumococcal vaccine with their physicians than patients in the control group (87/221 [39.4%] vs 21/212 [9.9%]; relative risk [RR], 3.97 [95% confidence interval [CI], 2.71-5.83]), and were more than 5 times as likely to have received the pneumococcal vaccine than the control group (44/221 [19.9%] vs 8/212 [3.8%]; RR, 5.28 [95% CI, 2.80-9.93]). In a multivariate analysis controlling for race, sex, education, insurance status, age, level of physician training, health status, and vaccine indication, only assignment to the intervention group was statistically significantly related to the probability of being immunized or discussing the issue with their physicians (P<.001 for both trends).

CONCLUSIONS

A simple, low-literacy educational tool increased pneumococcal vaccination rates and patient-physician discussions about the vaccine in an elderly, low-literate, indigent, minority population.

Glyceraldehyde-3-phosphate dehydrogenase from Ehrlich ascites carcinoma cells its possible role in the high glycolysis of malignant cells

Glyceraldehyde-3-phosphate dehydrogenase has been purified to apparent homogeneity from Ehrlich ascites carcinoma (EAC) cells. The enzyme is quite active over a pH range of 7.5-9.0 with an optimum pH of 8.4-8.7. The specific activity of the enzyme is much higher than that from other normal sources. In contrast to enzyme obtained from rabbit muscle, the EAC cell enzyme is not significantly inhibited by physiological concentrations of ATP at physiological pH. Kinetic studies using different substrates and inhibitors indicate that the properties of the EAC cell enzyme are significantly different from those of glyceraldehyde-3-phosphate dehydrogenase obtained from other normal sources. The striking dissimilarity of the malignant cell glyceraldehyde-3-phosphate dehydrogenase compared with this enzyme from other normal sources, particularly in respect to the interaction with ATP, may in part explain the high glycolysis of malignant cells.

Breeding habitats & seasonal variation in the larval density of Aedes aegypti (L) & Ae. albopictus (Skuse) in an urban garden in Calcutta city

A longitudinal study on the breeding habitats and variation in the relative larval density of Ae. aegypti and Ae. albopictus was conducted in an urban garden in Calcutta city. The observations of the study, during October 1995 to September 1996 revealed that both the species showed preference for breeding in earthen, and cement pots, plant pots, chowbachhas and molluscan shells. Ae. albopictus larvae were also found in accumulations of water in bamboo stumps and tree holes. The container positivity and relative larval density of both species was highest during monsoon (June 1996-September 1996) and lowest during summer (February 1996-May 1996). The seasonal variation in container index (CI) of each species was statistically significant (P < 0.05) and showed a positive correlation with rainfall, the seasonal variation in the larval density of both Ae. aegypti and Ae. albopictus in permanent breeding sites was however not statistically significant, indicating that the CI and relative larval density of the two species was unaffected by temperature and humidity. The variation between the larval density and their CI in the same season was not significant, suggesting a perfect adaptation of Ae. aegypti, an urban, and Ae. albopictus, a sylvatic species, to more or less similar aquatic biotypes in an urban garden.

The carvedilol hibernation reversible ischaemia trial; marker of success (CHRISTMAS). The CHRISTMAS Study Steering Committee and Investigators

BACKGROUND

Carvedilol improves left ventricular (LV) function when heart failure is due to LV systolic dysfunction, but the magnitude of the response is heterogeneous among patients with coronary disease, possibly reflecting the presence or volume of hibernating myocardium.

AIMS

The primary objective of the study is to determine whether the presence of hibernating myocardium predicts the magnitude of improvement in LV ejection fraction in response to carvedilol among patients with heart failure and LV systolic dysfunction due to coronary disease.

METHODS

The study is a prospective, randomised, parallel-group, double-blind, multi-centre study comparing carvedilol and placebo over a period of approximately 6 months in the above patient population. The primary end-point is the comparison of the mean change, from baseline to the final visit, in radionuclide-determined LV ejection fraction among patients on placebo with those on carvedilol stratified according to the presence of hibernating myocardium. Hibernating status will be determined by a combination of echocardiographic and myocardial perfusion (technetium-99m sestamibi) imaging.

RESULTS

255 patients have undergone screening tests of which 207 have been randomised so far. The study intends to randomise 400 patients and the first report of results is expected in 2000.

CONCLUSIONS

As far as we are aware this is the first randomised controlled trial to investigate the effects of treatment in patients stratified according to the presence of hibernating myocardium. The study will provide insights into the prevalence of myocardial hibernation, its natural history, and its influence on prognosis as well as the interaction between the presence of hibernating myocardium and the effects of treatment with carvedilol.

Muscle substrate utilization and lactate production

Biopsies (biceps) were examined in 8 bodybuilders across a typical arm-curl training session (80% 1-RM). [PCr] and [glycogen] decreased 62 and 12% after 1 set (n = 4), and 50 and 24% after 3 sets (n = 4). [Lactate] was 91 and 118 mmol &times kg-1, respectively, after 1 and 3 sets. Fatigue was probably partially caused by decreased [PCr] and increased [H+] (first set) and by decreased [H+] in subsequent sets.

Altered lipid peroxidation and antioxidant potential in human uterine tumors

A comparative study of lipid peroxidation and antioxidant potential has been made in human uterus and uterine tumor. Two types of uterine tumor used are: tumor (I), a fibroid which is the commonest benign solid tumor in uterus and tumor (II), an adenomyoma. Tumor microsomes are less susceptible to lipid peroxidation induced by both enzymic (NADPH-ADP-Fe3+ and xanthine-xanthine-oxidase) and non-enzymic (ascorbate-Fe2+) systems except in the case of tumor (II) microsomes when induced with xanthine-xanthine oxidase. Resistance of tumor microsomes to lipid peroxidation is associated with the low content of substrates in the form of polyunsaturated fatty acids (PUFAs), higher level of alpha-tocopherol, reduced glutathione and protein thiols and altered enzymic antioxidant potential (catalase and superoxide dismutase).

Differential expression of linker histone variants in Euplotes crassus

Two genes have been cloned from the ciliate Euplotes crassus that encode proteins with sequence similarity to the linker histones from a variety of organisms. One gene, H1-1, is present on a 1.3-kb macronuclear DNA molecule and encodes a 16.2- kDa protein. The second gene, H1-2, is present on a 0.7-kb DNA molecule and encodes an 18.8-kDa protein. Both H1-1 and H1-2 are expressed in vegetative cells, but the two genes exhibit very different patterns of expression during macronuclear development. H1-1 transcripts accumulate during conjugation and during the final rounds of DNA amplification. H1-2 transcripts accumulate after the onset of polytene chromosome formation and remain high throughout the remainder of macronuclear development. H1-1 is the major perchloric-acid-soluble protein from macronuclei. The pattern of gene expression and the macronuclear location of the H1-1 protein indicate that H1-1 is the predominant linker histone in vegetative macronuclei.

Effect of ammonium and nitrate ratio on glucose oxidase activity during gluconic acid fermentation by a mutant strain of Aspergillus niger

Of the factors tested, the source and concentration of carbon and nitrogen in the medium exerted maximum effect on growth and acid production. Glucose (15%) and urea (0.14%) induced glucose oxidase synthesis and optimum yield of calcium gluconate. Potassium dihydrogen phosphate (0.2%) and magnesium sulphate (0.06%) stimulated glucose oxidase activity and calcium gluconate production. Borax at a concentration of 1.5 g/L induced maximum glucose oxidase and calcium gluconate production with increased glucose utilization.

Capnography. A key underutilized technology

Based on the multiple applications and the potential cost savings, every ICU should have enough capnography for all intubations and probably for all mechanically ventilated patients. Of the multiple clinical applications of capnography, most attention should be focused on its use with intubation and resuscitation. Other applications, such as blood gas and ventilation-perfusion scan reduction, should be instituted after the primary areas have been implemented. While capnography modules may appear to be expensive at first glance, an analysis of their clinical application reveals they can save the hospital hundreds of thousands of dollars beyond the purchase price.

Giant sigmoid diverticulum: a report of three cases

The imaging appearances of three patients with a giant sigmoid diverticulum are described. The prominent feature was a large gaseous lucency noted in the lower abdomen on plain radiographs. Computed tomography (CT) was undertaken in two cases and in these a large gas filled collection was identified containing a small quantity of fluid. In the third case the collection was aspirated, contrast medium injected and a communication with the large bowel demonstrated. The condition is uncommon and needs to be distinguished from sigmoid and caecal volvulus.

Primary subtype C HIV-1 infection in Harare, Zimbabwe

Heterosexual transmission of HIV-1 is widespread in Southern Africa. Heteroduplex mobility assays (HMA) and phylogenetic analyses of V3-V5 envelope (env) gene sequences demonstrate that subtype C predominates in Zimbabwe. To elucidate factors contributing to the epidemic in Zimbabwe, clinical and virologic characteristics of recently acquired subtype C HIV-1 infection among 21 men and 1 woman were determined. In 12 of 19 men providing clinical histories, a sexually transmitted infection preceded serologic evidence of HIV-1, and 14 of 19 men complained of rash or fever before seroconversion. Quantitative p24 antigen levels, reverse transcriptase activity, and HIV RNA levels of 22 viral isolates correlated with in vitro infectivity in peripheral blood mononuclear cells (p < .05). Biologic phenotype assessed in MT-2 cells demonstrated that 3 of 22 isolates (14%) were syncytia inducing (SI) and the remaining 19 nonsyncytium inducing (NSI). Early growth of virus in culture was associated with increased plasma HIV RNA levels, decreased CD4 cell levels, and SI virus. Recent subtype C HIV-1 infection through heterosexual transmission in Zimbabwe demonstrated clinical and virologic features consistent with reports of seroconversion to subtype B viruses.

Survival of olfactory memory through metamorphosis in the fly Musca domestica

Metamorphosis in the fly (Musca domestica) involves extensive lysis, neurogenesis and reorganization of neural tissue. Despite this, two experiments are reported which show aspects of larval memory persist into the adult form. Experimental larvae were reared in sawdust scented with aversive odours (mint or geraniol). Control larvae were reared on plain sawdust. In blind post-metamorphosis testing using a Y maze, adult flies showed a preference for the specific odour to which the larvae had been exposed. Control flies found both test odours aversive. A second experiment explores the possible role of cell survival through metamorphosis as a mechanism of the persistence of memory. Cells from trained donor flies when grafted into untrained recipients produced specific changes in recipient odour preference reflecting the donor larvae training.