A survey of synthetic HIV-1 peptides with natural and chimeric sequences for differential reactivity with Zimbabwean, Tanzanian and Swedish HIV-1-positive sera

OBJECTIVE

To determine whether the known sequence differences between African and non-African HIV-1 strains are reflected in the serological response.

DESIGN AND METHODS

We investigated the antibody reactivity of 34 Swedish, 30 Tanzanian and 42 Zimbabwean HIV-1-positive sera to 67 synthetic peptides with sequences from North American and African HIV-1 isolates, mostly derived from regions of gag and env known to be antigenic. Not all sera were tested against all peptides.

RESULTS

Differences in frequency of reactivity were noted with peptides covering the entire third variable domain (V3), which is a primary neutralization determinant, and the carboxyl terminus of gp120, in two regions of gp41, and the carboxyl terminus of p24. In env Tanzanian sera reacted preferentially with a V3 peptide from the strain JY1 (Zaire). Gradual substitutions in the central motif in V3 of ELI from GLGQ to GPGR, typical of many non-African strains, led to a gradual increase in reactivity of many Swedish sera, but did not affect Tanzanian and Zimbabwean sera, suggesting that the major epitopes recognized by these African sera are outside GPGR. V3 peptides from the MN and Z3 strains reacted with most sera, but missed 30% of those of Tanzanian origin. In the carboxyl terminus of gp120 both sets of African sera reacted preferentially with peptides from strains JY1 and MAL. Swedish sera reacted strongest with analogues from strains Z321 and HXB2. In gp41, Swedish sera showed a weak preference for reactivity with HXB2-derived peptides in the immunodominant region (amino acids 590-620), and further towards the carboxyl terminus (amino acids 620-665).

CONCLUSION

The differences in serological reactivity were as great between Zimbabwe and Tanzania as between the two African sets and the Swedish. The geographical differences in the pattern of reactivity with HIV peptides probably depend on both host and viral variation and may be developed into a seroepidemiological tool, useful for optimization of future HIV vaccines.

Multilayer interference filters for the far-infrared and submillimeter regions

The theoretical and experimental aspects of an alternative approach to the construction of interference filters for wavelengths greater than 80 microm are described. The filters consist of a number of thin plastic sheets with films of a high refractive index deposited onto one or both sides of each sheet. These are then heat bonded to form a self-supporting optical multilayer filter. Experimental results are presented for a number of filters produced in this way. Reflectances of the order of 90% have been measured for wavelengths as high as ~200 microm. By successive reflections from two or more such multilayers it is possible to produce efficient, narrow-bandpass filters with blocking over extended spectral regions. The possibility of the construction of other devices, including even narrower bandpass filters and wideband beam splitters, is also discussed.

Election spin resonance studies of free radical formation and oxygen consumption of lens epithelium during ultraviolet exposure

A long life election spin resonance (ESR) signal at g = 2.0006 was observed in the normal lens epithelium and cortical fibers. During ultraviolet (UV) exposure, a new ESR signal at g = 2.0060 was found in the lens epithelium. But this specific signal was not detected in the lens cortical fibers. This suggested that lens epithelial cells were more susceptible to the free radical formation which was induced by UV light. By means of ESR spin probe oximetry, the oxygen uptake of lens epithelial cells was measured. The more the oxygen uptake, the higher the K value was. The K value of the oxygen consumption of epithelial cell linearly correlated with time of consumption (20-60 min) and increased as a function of UV exposure time (1-5 min). The oxygen consumption rate of lens epithelial cell was approximately 1.38 x 10(6) and increased to 7.1 x 10(6) O2 molecules per cell per sec. The oxygen consumption rate increased more than 5 times. These results indicates that UV light can accelerate the respiratory function of lens epithelial cells. The necessity of excess oxygen of lens epithelial cells may play a role in the cataract formation induced by UV light.

Intestinal parasites and HIV infection in Tanzanian children with chronic diarrhea

OBJECTIVE

To determine whether specific intestinal parasites are associated with HIV infection in Tanzanian children with chronic diarrhea.

DESIGN

A prospective, cross-sectional study.

SETTING

Muhimbili University College of Health Sciences, Dar es Salaam, Tanzania.

SUBJECTS

All children aged 15 months to 5 years admitted with chronic diarrhea, and age-matched controls.

METHODS

Standardized history, physical examination, HIV serology, and stool parasitology were evaluated for all subjects. We compared three groups: HIV-infected and non-HIV-infected children with chronic diarrhea and controls without diarrhea.

MAIN OUTCOME MEASURES

Fecal parasites and nutritional status.

RESULTS

Chronic diarrhea accounted for one-quarter of all cases of diarrheal disease in the defined age range, and children with chronic diarrhea were severely malnourished. Forty per cent of subjects with chronic diarrhea were HIV-seropositive. Although intestinal parasites were detected in approximately 50% of all three groups, diarrheagenic parasites were detected in up to 40% of children with chronic diarrhea. Blastocystis hominis was detected only in HIV-infected patients.

CONCLUSIONS

HIV infection was common in children with chronic diarrhea, and parasitic agents of diarrhea may be important in children with chronic diarrhea both with and without HIV infection in this setting. B. hominis was more frequent in HIV-infected children. The immunocompromising effects of severe malnutrition may have diminished the difference between HIV-infected and non-HIV-infected children.

[Preparation of sucking tablet of shengmei] off

The Sucking Tablet of Shengmei is made from eight Chinese traditional drugs including Radix Adenophorae, Fructus Mume, etc. The effective rate of the tablet in treating chronic pharyngitis reaches up to 96 percent. The working mechanism related to the fact that the tablet is bacteria-resistant and helps to strengthen the body function. This paper presents the preparation process of the Sucking Tablet along with solutions for some problems encountered in the process and appropriate standards for quality control.

Retinoic acid inhibition of serum-induced c-fos transcription in a fibrosarcoma cell line

We investigated the mechanism by which retinoic acid causes growth arrest and flat reversion of SSV-NRK, simian sarcoma virus-transformed normal rat kidney cells. Northern analysis revealed that both chronic (7 days) and acute (6 h) retinoic acid treatment of serum-stimulated SSV-NRK cells caused a 6-fold decrease in c-fos mRNA levels. In addition, nuclear run-on experiments showed that retinoic acid regulated c-fos expression in SSV-NRK cells at the transcriptional initiation level. Attenuation of c-fos transcription was equal in both retinoic acid-treated and control cells, and no increased c-fos mRNA turnover was detected in retinoic acid-treated cells. Furthermore, there was no observed change in the c-fos mRNA levels after only 30 min of retinoic acid treatment, suggesting that a mechanism involving the interruption of the signal transduction mechanism at the membrane level is unlikely. Because it has been shown that c-fos expression plays a pivotal role in mitogenesis of quiescent fibroblasts, we conclude that the retinoic acid-mediated down-regulation of c-fos expression is a mechanism for growth inhibition in SSV-NRK cells.

The AIDS epidemic in Tanzania: rate of spread of HIV in blood donors and pregnant women in Dar es Salaam

The prevalence of antibodies to HIV in population groups in Dar es Salaam, Tanzania has been monitored from late 1984 through 1991. In the pregnant women and blood donors the doubling time was about 2 years. If, however, the doubling time is calculated from reported cases of AIDS of the whole country, an average doubling time of 10 months is obtained. We point out factors that may bias calculations of the rate of spread of the virus and thus give rise to erroneous projections for the nearest years, especially the so-called transient effect. It is recommended that serosurveys of representative population groups are carried out at regular intervals.

[An approach to the preparation of digestive enzyme-drug for oral administration: complex lactase microcapsules]

Complex microcapsules which could protect enzyme drugs from inactivation in both the stomach and intestine were prepared. In the process, semipermeable microcapsules were first formed by enveloping the enzymes within spherical, ultrathin semipermeable membranes. To resist gastric juice, the semipermeable microcapsules were further encapsulated by enteric-soluble materials to form complex microcapsules. When the preparations were taken into the intestine, the semipermeable microcapsules were released and small molecular substrates could then equilibrate rapidly across the semipermeable membrane to be acted on by the enveloped enzymes, while alimentary proteases remained outside. This complex microcapsulated lactase could retain over 65% of its activity after simulation in gastric juice for 2 h, and over 60% of its activity was retained after 6 h in pancreatin-containing simulated intestinal juice. On the contrary, unencapsulated lactase lost all activities immediately under the same conditions.

Oral yeast flora of a population in an area of Tanzania bordering an AIDS endemic zone

Mouth swabs from 1,288 individuals in the North Mara region of Tanzania were cultured for yeasts. Subjects were randomly selected from rural and urban areas, and a group of food handlers were also studied. Yeasts were cultured from 407 (31.6%) and Candida albicans from 141 (10.9%) subjects. A wide variety of other yeast species were also identified.

Seroepidemiological correlations of antibodies to human herpesviruses and human immunodeficiency virus type 1 in African patients

A seroepidemiological evaluation of the humoral immune response against human herpes viruses was carried out in patients with and without HIV infection in Tanzania to study the role of these viruses as a cofactor in AIDS. Serum specimens were obtained from 321 outpatients and 100 healthy schoolchildren of a rural population in the Kagera Region, Tanzania, and from 149 inpatients of an urban population in Dar-es-Salaam, Tanzania. The data were analysed by logistic models taking into account demographic variables. The data obtained revealed no differences in the prevalence of antibodies to human herpes viruses between the different groups. Therefore, our study under the present conditions and the observed stages of AIDS does not suggest an influence of HIV infection on human herpesvirus infection or serologic response.

Estimating drug shelf-life with random batches

The problem of assessing the shelf-lives of drug products in the market is considered. We focus on the situation where the drug characteristic of interest has a linear relationship over time and batch-to-batch variation is present. Two methods for assessing shelf-lives are proposed based on the weighted least squares method under a regression model with random coefficients. An application to some stability data from the pharmaceutical industry is presented.

Assessment of bioequivalence using a multiplicative model

In many bioavailability/bioequivalence studies, the distributions of responses such as AUC and Cmax are often positively skewed and exhibit a lack of homogeneity of variances. In this situation, a logarithmic transformation is usually considered for reduction of skewness and achievement of an additive model with relatively homogeneous variance. In this paper, consideration is given to a multiplicative model based on empirical evidence. A method is proposed using individual subject ratios for assessing the bioequivalence of two different formulations. This method is then subsequently extended to several commonly used crossover experiments.

Acid-labile anchoring linkages for solid phase synthesis of C-terminal asparagine peptides using the Fmoc strategy

Two acid-labile substituted benzylamine type anchoring linkages, 4-benzoxy-2,6-dimethoxybenzylamine and 2-benzoxy-4,6-dimethoxybenzylamine, for solid phase synthesis of peptide amides were prepared. The Na-9-fluorenylmethyloxycarbonyl (Fmoc) amino acids could be easily attached to the resins with DCC/HOBt (loading 0.5-0.6 mmol/g resin). After final removal of the Na-protecting groups, treatment with TFA (50-95%) yielded amino acid and peptide amides in high purity. As we could show for the synthesis of thymulin (FTS, pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn), these two resins with anchoring linkages are well suited for the synthesis of C-terminal Asn peptides using protected aspartic acid derivative as starting material.

Evaluation of simple tests for detection of HIV antibodies: analysis of interobserver variation in Tanzania

200 sera were tested for HIV antibodies with different tests in Tanzania. The results were interpreted by 5 different observers with different laboratory experience. There was considerable variation between observers and between testing methods. HIV-Chek was easiest to perform with little interobserver variation, but a few probably false negative readings were seen. Serodia gave many false positives. Western Blots gave more diverging results due to indeterminate sera and lack of training. HIV-Chek seems best when time, facilities, and training are limited and if combined with Serodia false negative results can be excluded.

Test for batch-to-batch variation in stability analysis

We propose several statistical tests for batch-to-batch variation in the stability analysis of a drug product and present applications with data from new drug application stability and marketing stability analyses.