The site of antiviral action of 3-nitrosobenzamide on the infectivity process of human immunodeficiency virus in human lymphocytes

The C-nitroso compound 3-nitrosobenzamide, which has been shown to remove zinc from the retroviral-type zinc finger of p7NC nucleocapsid proteins, inhibits acute infection of human immunodeficiency virus type 1 in cultured human lymphocytes. The attachment of the virus to lymphocytes and the activities of critical viral enzymes, such as reverse transcriptase, protease, and integrase, are not affected by 3-nitrosobenzamide. However, the process of reverse transcription to form proviral DNA is effectively abolished by the drug, identifying the mode of action of 3-nitrosobenzamide as interrupting the role of p7NC in accurate proviral DNA synthesis during the infectious phase of the virus life cycle.

Vector theory of diffraction by a single-mode fiber: application to mode-field diameter measurements

We derive a far-field diffraction integral by (vector) electromagnetic theory; the result differs from the (scalar) Rayleigh-Sommerfeld or Kirchhoff result in that it depends on polarization. For unpolarized light, we derive a factor (1 + cos(2) theta)((1/2))/ radical2 that replaces the usual obliquity factor. Omitting this factor can cause an error of the same order as the measurement uncertainty in determining the mode-field diameter of a single-mode fiber from far-field data.

Brutality to twins in south-eastern Nigeria: what is the existing situation?

Following rumors of some persistence of abuse on twins, a survey was conducted from January through June, 1991 in the rural areas of Efik, Ibibio and Annang tribes of South-Eastern Nigeria to determine the current attitude of the people towards twins and their mothers. Of the 619 women interviewed, 56% cherished having twins; 35% would not desire largely because of the economic and other minor difficulties associated with their up-keep but none of these would abandon the infants. The remaining 9% hold a taboo against twins: as babies derived from the devil, non-human and punishment from the gods for sinfulness. Consequently, 2.3% and 2.6% of the mothers would have their twins rejected and killed respectively and 6% of the twin mothers would be cast out but none killed by their husbands' families. The intention to perpetuate this form of abuse was elicited in all the three tribes but seemed relatively to be most pronounced in Annang people. The information generated, though limited to rural population, suggests that the rejection of twin births has actually not yet disappeared from this part of the country. Health workers in South-Eastern Nigeria who encounter twins with failure to thrive should consider rejection as a possible contributing factor. It would need intensive moral education and religious teaching to stem this brutal culture.

Evaluating needle exchange: are there negative effects?

OBJECTIVE

We analyzed data on all drug-treatment admissions in San Francisco County over a 4-year period (n = 35,460) to evaluate the potential negative effects of the San Francisco needle-exchange program.

METHODS

Admissions in the 2 years preceding implementation of the exchange program (1987-1988) were compared with admissions in the 2 years following implementation (1989-1990).

RESULTS

No negative consequences of needle exchange were detected. Specifically, the presence of the exchange program was not associated with (1) increases in injection drug use, (2) increases in needle-sharing behavior, or (3) changing drug-use behavior from non-injection to injection. We also compared high-drug-use neighborhoods with and without local needle-exchange sites. Neighborhoods without needle-exchange sites showed a greater increase in proportion of admissions for injection drug use, and in frequency of injection, over time.

CONCLUSIONS

Because of methodological limitations, our findings are preliminary. Longitudinal studies comparing needle-exchange and non-exchange cohorts are needed to further evaluate effects of this intervention.

Cause of death in multiple endocrine neoplasia type 1

OBJECTIVE

Little data are available on the natural history of untreated multiple endocrine neoplasia type 1 (MEN-1). These data are essential in deciding treatment that may carry significant morbidity. We determined the causes of death in a large MEN-1 kindred with data available over a period of 130 years. Most cases were unrecognized as MEN-1 at the time of patient's death.

DESIGN

Retrospective study of recorded medical data from 1861 to 1991.

PATIENTS

One hundred fifty-nine deaths occurred, of which 46 were in individuals classified as "highly probable" of having MEN-1.

RESULTS

Of 46 deaths in those classified as "highly probable" of having MEN-1, 20 (43.5%) died of a recognized complication of MEN-1 (12 of malignant neoplasms, six of renal calculi, and two of peptic ulcer). If accidental deaths are excluded, 50% of the deaths in patients with MEN-1 were the result of MEN-1, and the mean age of death (50.9 years)was significantly younger than that of other family members.

CONCLUSIONS

It is concluded that MEN-1 leads to premature death, and that neoplasia rather than peptic ulcer disease is the main cause of death. Deaths from pituitary tumor or malignant endocrine tumors within the thorax were just as common or more common than deaths from pancreatic malignant neoplasms.

A measure of mortality risk for elderly patients with acute myocardial infarction

The objective of this study was to derive and validate a simple scoring system that predicts risk of short-term mortality in elderly patients hospitalized with acute myocardial infarction (AMI) and to compare this derived score with the MedisGroups admission severity score. A myocardial infarction severity score (MISS) was derived from a database of clinical information abstracted using MedisGroups and follow-up information on 30-day mortality status. The MISS was validated and compared with the MedisGroups Admission Severity Groups (ASGs) in a separate database. The derivation set included 2,037 Medicare patients 65 years old or older with confirmed AMI who were randomly selected from patients discharged from hospitals in seven states during 1985. The validation set consisted of 6,323 patients from the 1988 MedisGroups comparative database who were at least 65 years of age and had confirmed AMI. Multivariate logistic regression analysis found a set of nine abnormal patient characteristics that independently predict 30-day mortality. There was good agreement between mortality rates predicted by the logistic model and observed mortality rates in the validation population. This regression model was then simplified to an additive score where eight of the characteristics were weighted as one point and one characteristic was weighted as two points. The MISS is the sum of the points for each patient. In the validation dataset, the 1,373 patients with the lowest MISS scores had a mortality rate of 4.6% and the 400 patients with the highest MISS scores had a mortality rate of 64%.(ABSTRACT TRUNCATED AT 250 WORDS)

Diverse mechanisms of control of aromatase gene expression

The synthesis of estrogens from androgens is catalyzed by a microsomal cytochrome P450 termed aromatase (P450arom). The expression of this enzyme is highly regulated in both a developmental and cell-type specific fashion. We have chosen to examine the molecular basis of aromatase gene regulation by studying two models of aromatase expression: the Sebright bantam chicken and the R2C rat Leydig tumor cell line. In the first model, affected (Sebright) chickens express aromatase in many extragonadal tissues, while normal Leghorn chickens express aromatase only in the ovary and hypothalamus. Our studies have demonstrated that in normal chickens the site of transcription initiation is located approx. 147 nucleotides upstream of the initiator methionine. While Sebright animals also express aromatase mRNA initiated at an analogous initiation site in the ovary, a distinctive species of aromatase mRNA is also detected and is present in ovary and extragonadal tissues. This mRNA contains an identical coding sequence, but contains an alternatively spliced 5' noncoding exon that is derived from a distinctive promoter. The second model, the R2C Leydig tumor cell line, provides ample contrast. This cell line expresses high basal levels of aromatase (150-200 pmol/h/mg protein) that is suppressed with administration of 8 bromo cAMP or forskolin but the activity is not altered by glucocorticoids or epidermal growth factor treatment. Despite this distinctive pattern of regulation, at least three species of aromatase mRNA are detected in Northern blots, each of which is also detected in rat ovary. Primer extension and S1 nuclease assays indicate that both granulosa cells and R2C cells utilize a promoter that is located approx. 97 nucleotides upstream of the initiator methionine. These studies suggest that the "ovarian" promoter is evolutionarily conserved in both rats and chickens. These results further imply that the genetic mechanisms controlling the diversity of aromatase expression among tissues and among different species are likely to fall into two groups: those that employ distinctive promoters and alternative splicing and those that effect different patterns of regulation through a common ("ovarian") promoter.

Cytotoxic effect of ascorbate and its derivatives on cultured malignant and nonmalignant cell lines

The effect of L-ascorbate and its derivatives on the growth of malignant and nonmalignant cell lines has been examined. L-Ascorbate and its oxidative product dehydroascorbate were cytotoxic or lethal to the fast-growing malignant cells, but they were less toxic to nonmalignant cells. Two isomers of ascorbate, D-ascorbate and D-isoascorbate, both with 5% of the antiscorbutic potency and very high turnover rate, had similar activities. The cytotoxic effect of ascorbate was apparently not related to the metabolic or vitamin activities of ascorbate at the cellular level. Furthermore, studies on the viability of treated cells indicated that the observed effect on cell growth was not cytostatic in nature but was the result of a direct cell-killing action of ascorbate. Several groups of ascorbate derivatives were also tested; many of them were toxic to these cells. The results support the hypothesis that the cytotoxic activity of ascorbate was due to its chemical properties and that certain oxidation and degradation products of ascorbate were cytotoxic agents.

Unusual lymphangioma observed prenatally in a 45,X fetus

We present a case of a large frontal lesion, suspected on antenatal ultrasound to be a cephalocele. The cardiac anatomy was abnormal and fetal blood sampling showed a 45,X chromosome constitution. Postmortem examination proved this to be a lymphangioma and confirmed the presence of a cardiac defect. We suggest that this lymphangioma represents an unusual manifestation of monosomy X and discuss the importance of doing chromosome analysis in the presence of such a lesion which is of similar appearance as a cephalocele.

[Manner of birth and otitis media]

BACKGROUND

There are many risk factors associated with the occurrence of otitis media; cesarean section could be one of them.

REPORT

Two hundred and eighty four children were treated during the first three years of life by the same pediatric service. 47% of these children were treated for otitis media and 53% were not. 41% were delivered by cesarean section, and 59% were vaginal births. The incidence of otitis media in the cesarean section group was 0.504, versus 0.449 in the vaginal birth group.

RESULTS

These data indicate that the fraction of risk of having otitis media that is attributable to cesarean section is 11%; the relative risk is 1.12.

CONCLUSION

The observed effect is not large enough to confirm that cesarean section is a risk factor, but suggests that a carefully controlled prospective study should be conducted.

A mutation (Met-->Arg) in the type I keratin (K14) gene responsible for autosomal dominant epidermolysis bullosa simplex

We have identified a single base change in exon 4 of the type I keratin gene which results in the replacement of a methionine for an arginine residue at codon 272 in an Irish family displaying an autosomal dominant simplex (Koebner) form of epidermolysis bullosa (EB). This family had previously provided tentative evidence for linkage to genetic markers on chromosome 1q. The mutation cosegregates with the disease, producing a lod score of 4.8 at theta = 0.

Purification and characterization of the mouse mammary tumor virus protease expressed in Escherichia coli

The mouse mammary tumor virus (MMTV) protease gene was cloned into pGEX-2T, an Escherichia coli expression vector containing the glutathione S-transferase coding region of Schistosoma japonicum. The chimeric protein was formed by fusion of the glutathione S-transferase with a hexapeptide which contains a thrombin cleavage site, followed by the MMTV protease. Affinity chromatography on a glutathione-Sepharose 4B column was used to isolate the chimeric protein. After thrombin cleavage, the glutathione S-transferase and the protease were separated by gel filtration chromatography on a Sephadex G-75 column. The overall yield of the protease purification procedure was about 1 mg of protease/liter of culture, and the specific activity was 380 pmol/min.micrograms of enzyme. Like other retroviral proteases, the MMTV enzyme was active as a dimer, showed maximum activity at pH between 4 and 6, and could be inhibited by pepstatin A and a phosphinic acid derivative HIV-1 protease inhibitor. Enzymatic characterization of this protease reveals its broad specificity, showing a clear preference for the oligopeptide substrate mimicking the cleavage site at the amino-terminal end of the capsid protein (kcat/Km = 9725.5 M-1.s-1). The chimeric protein was also an active dimer and showed a similar Km (17 microM) for such an oligopeptide, although its kcat was about 10 times smaller. Autocatalytic processing of the MMTV protease was observed after expression of clones containing the natural cleavage site, as it occurs at the amino-terminal end of the viral protease, instead of the thrombin-sensitive sequence.

Fluoroquinolone supersusceptibility mediated by outer membrane protein OprH overexpression in Pseudomonas aeruginosa: evidence for involvement of a nonporin pathway

Overexpression of Pseudomonas aeruginosa outer membrane protein OprH led to an 8- to 32-fold increase in susceptibility to chloramphenicol and the quinolones nalidixic acid, norfloxacin, ciprofloxacin, and fleroxacin in comparison with the susceptibility of the wild-type strain H103 grown on Mg(2+)-sufficient medium. This was true regardless of whether OprH overexpression was induced by growth of strain H103 on Mg(2+)-deficient medium, the addition of 5 mM m-toluate to cells containing the cloned oprH gene behind the inducible tol promoter in plasmid pGB25, or mutation in the polymyxin-resistant derivative strain H181. In contrast, OprH overexpression failed to reverse the quinolone resistance phenotype of a nalB mutant. OprH was purified to homogeneity by selective detergent solubilization and fast protein liquid chromatography. The addition of OprH to the solution bathing a black lipid bilayer membrane failed to give rise to an increase in membrane conductance. This suggests that OprH is not a porin but, instead, may cause increased uptake of quinolones and chloramphenicol via a non-porin pathway.

Kinetics of dissolution of gaseous halothane in Krebs-Ringer's solution

The responses of biological tissues to volatile anaesthetics are commonly studied by incubating specimens in a bath containing dissolved anaesthetic. One accepted technique is to bubble an anaesthetic gas into several incubation chambers simultaneously. To assess the validity of this technique in producing dissolved anaesthetic (the biologically active form) at equal rates among the several chambers, we determined the kinetics of dissolution of halothane gas in three tissue incubation chambers containing Krebs-Ringer's solution. We found that (1) the dissolution kinetics were first-order in all three chambers; (2) the rate of halothane dissolution depended on the gas bubbling rate; (3) even with the same bubbling rates, chamber shapes and chamber volumes, the dissolution rates for the three chambers were not equal, suggesting that dissolution rate depended on small differences in chamber geometry; (4) the dissolution rates could be made equal by adjusting chamber bubbling rates according to calculations involving the first-order rate equation; and (5) the maximum coefficient of variation of dissolved halothane concentration was 9% at 63% approach to equilibrium and 3% at equilibrium.

Subglottic ulceration and healing following endotracheal intubation in the neonate: a morphometric study

In neonates, acquired subglottic stenosis is the most serious long-term complication of endotracheal intubation and is due primarily to posttraumatic fibrosis of the infant larynx. We have examined 78 larynges, 75 of which were intubated, from infants ranging in gestation from 22 to 40 weeks, and who survived from a few hours to up to 300 days. Each larynx was morphometrically assessed for the extent of acute injury, indicated by the percentage of epithelial loss, and healing, indicated by the percentage of a subglottic ulcer covered by metaplastic squamous epithelium. Results show that acute injury is almost invariable, and up to 100% of the subglottic epithelium may be lost within a few hours of intubation, but that progression of injury is relatively short-lived. Ulcer healing starts after a few days, rapidly progresses from day 10, and in the majority of cases is complete after 30 days. This study suggests that long-standing acute injury in the subglottis is the exception rather than the rule, even with the endotracheal tube remaining in place.

Testosterone and 5 alpha-dihydrotestosterone interact differently with the androgen receptor to enhance transcription of the MMTV-CAT reporter gene

Testosterone and its 5 alpha-reduced derivative 5 alpha-dihydrotestosterone exert different actions in the male during embryogenesis and in postnatal life. Nevertheless the two hormones bind to the same intracellular androgen receptor, and genetic and endocrinological studies in the Tfm mouse suggest that the actions of both hormones are mediated by this single receptor. Previous studies indicate that dihydrotestosterone binds more tightly to the androgen receptor but that the Bmax of binding of the two hormones is the same. To determine whether these differences in binding parameters could explain the mechanism by which the two hormones exert different physiological actions via the same receptor, we introduced a plasmid encoding the androgen receptor cDNA and a reporter plasmid encoding MMTV-CAT into Chinese hamster ovary cells. These cells do not express endogenous androgen receptor and do not convert testosterone to dihydrotestosterone. Therefore, it was possible to examine the relation between the concentration of each of the steroids and reporter gene expression. Both hormones enhanced CAT activity, but dihydrotestosterone was approximately 10 times as potent (half maximal of 0.018 nM) as testosterone (half maximal of 0.2 nM); the maximal activity achieved was the same for the two androgens. These findings are nearly identical to the apparent Kd values for the interaction of the two hormones with the androgen receptor. Although testosterone and dihydrotestosterone may influence the expression of other genes differently, these findings are compatible with a model system in which the differential effects can be explained as a consequence of different binding affinities to the receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma of the pancreas with osteoclast-like giant cells: a case report with immunocytochemistry

Histological examination of a tumor centered in the body of the pancreas of a 65-year-old Iranian man revealed it to have a substantial component in which osteoclast-like giant cells were set within a stroma of pleomorphic mononuclear cells though other areas were composed of conventional adenocarcinoma. Immunocytochemistry was used to investigate the differentiation of the various component cells of the tumor. The carcinoma cells of the usual type expressed epithelial antigens (EMA and cytokeratin). The giant cells expressed vimentin and showed membrane staining with anti-LCA, in common with examples of cells originating from the mononuclear phagocytic system, including normal osteoclasts. The accompanying stromal cells expressed vimentin only. This implies that the giant cells are likely to have their origin in the bone marrow, whereas the mononuclear stromal cells that separate them may represent tumor cells that have lost their epithelial phenotype. The giant cells are therefore an unusual tissue response to the presence of the carcinoma.

An interesting case presentation: a possible new route for perinatal acquisition of Chlamydia

Chlamydia trachomatis is currently the most common sexually transmitted disease in the United States. The prevalence in pregnant women ranges between 2% and 47%. It is well known that C trachomatis can be transmitted from the genital tract of an infected mother to her newborn infant, causing conjunctivitis or pneumonia or both, along with their longstanding complications. A review of the literature failed to show, however, conclusive evidence of transmission of infection to the newborn infant when the infant was born by cesarean section with intact amniotic membranes. We present a case of a young black woman with a history of chlamydia cervicitis during pregnancy whose infant was delivered by cesarean section because of failure to progress. She gave birth to a healthy term infant who developed ophthalmia neonatorum on the 3rd day of life. Examinations of conjunctival scrapings with direct fluorescent staining (chlamydia MicroTrak) performed on the 1st and 3rd day of life were positive. The initial test was performed because of the maternal history. The infant was mildly symptomatic at the time the study was repeated for confirmation. Our findings strongly suggest the possibility of either transmembrane or transplacental route of infection in the pathogenesis of neonatal chlamydia infection. Further study is needed to confirm this possibility.