Delayed-type hypersensitivity testing in Tanzanian adults with HIV infection

Delayed-type hypersensitivity (DTH) testing and total lymphocyte counts as measures of cell-mediated immune function were assessed for medical patients in Dar es Salaam, Tanzania. DTH testing was performed with the Multitest CMI device which simultaneously administers seven antigens. Of 201 patients completing DTH testing, 90 were HIV seropositive. Anergy occurred more frequently among HIV-seropositive patients (39 of 90) as compared with HIV-seronegative patients (17 of 111). DTH skin test reactivity, measured by anergy, the number of positive antigens, and the combined DTH response induration, was significantly related to the clinical stage of HIV disease. Median total lymphocyte counts were significantly lower in HIV-seropositive patients than in HIV-seronegative patients (1,130 vs. 1,680 lymphocytes x 10(6)/L). Total lymphocyte counts decreased with increasing severity of HIV disease. In multivariable analysis, the number of positive antigens in DTH testing and lymphopenia significantly predicted HIV infection. The findings suggest that DTH testing and total lymphocyte counts may be useful, inexpensive tests of immune function in African patients with HIV disease.

HIV-1 proviral DNA sequences of env gp41 PCR amplificates from Tanzania

The polymerase chain reaction (PCR) and direct DNA sequencing were used to detect and characterize selected regions of the HIV-1 proviral genome in whole blood samples from Tanzania. Specific PCR amplification products were obtained in gag and/or env (gp41) regions from 15 of the 19 HIV-1 seropositive samples investigated. Env regions from 12 different amplificates were further characterized using the dideoxy sequencing method. Preliminary results indicate that, despite scattered nucleotide mismatches, HIV-1 gp41 amino acid sequences from Tanzania conform to the 1990 Los Alamos African consensus sequence and resemble the HIV-1 subtype A or D consensus sequences in the characterized regions.

CIF, an essential cofactor for TFIID-dependent initiator function

The core promoters for mammalian protein-coding genes often contain a TATA box, an initiator (Inr) element, or both of these control elements. The TFIID complex is essential both for TATA activity and for the activity of a common class of Inr elements characterized by an approximate consensus sequence PyPyA+1NT/APyPy. Although the complete set of proteins required for basal TATA-mediated transcription has been established, the requirements for TFIID-dependent Inr activity remain undefined. In this study we set out to reconstitute Inr activity with purified and recombinant general transcription factors. For this analysis, Inr activity was measured as the ability of an Inr to enhance the strength of a core promoter containing an upstream TATA box. Inr activity was not detected in reactions containing TFIIB, RAP30, RAP74, RNA polymerase II, and either TBP or TFIID, even though these factors were sufficient for TATA-mediated transcription from supercoiled templates. By use of a complementation assay, a factor that imparts Inr activity was identified. This factor, named CIF, stimulated Inr activity in reactions containing the TFIID complex, but activity was not detected with TBP. Further characterization of CIF suggested that it contains multiple components. Functional and immunological experiments demonstrated that one of the CIF components is the mammalian homolog of Drosophila TAF(II)150, which is not tightly associated with mammalian TFIID. These results reveal significant differences in the factor requirements for basal TATA and Inr activity. Further elucidation of these differences is likely to explain the need for the core promoter heterogeneity found within protein-coding genes.

G1 delay in cells overexpressing prostaglandin endoperoxide synthase-2

Colorectal cancer is the second leading cause of death from cancer in the United States. Continuous use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) has been shown to reduce the risk of colorectal cancer in humans by 40-50%. Patients with familial adenomatous polyposis who take NSAIDs, such as sulindac, undergo a regression of intestinal adenomas. Rodents exposed to carcinogens that cause colon cancer have a 50-60% reduction in the size and number of colonic tumors when treated continuously with NSAIDs. One common target for these drugs is prostaglandin endoperoxide synthase, also referred to as cyclooxygenase (COX). We and others have shown recently that COX-2 levels are increased dramatically in 85-90% of human colorectal adenocarcinomas and in 40-50% of colonic adenomas. We prepared intestinal epithelial cells that express the COX-2 gene permanently and found that they have altered adhesion properties and resist undergoing apoptosis. We report here that these cells also have a 3-fold increase in the duration of G1, lower levels of cyclin D1 protein, and a marked decrease in retinoblastoma kinase activity associated with cyclin-dependent kinase 4. The delay in G1 transit may relate to the resistance of these cells to undergo programmed cell death, which could affect their tumorigenic potential.

Peptide synthesis using unprotected peptides through orthogonal coupling methods

We describe an approach to the synthesis of peptides from segments bearing no protecting groups through an orthogonal coupling method to capture the acyl segment as a thioester that then undergoes an intramolecular acyl transfer to the amine component with formation of a peptide bond. Two orthogonal coupling methods to give the covalent ester intermediate were achieved by either a thiol-thioester exchange mediated by a trialkylphosphine and an alkylthiol or a thioesterification by C alpha-thiocarboxylic acid reacting with a beta-bromo amino acid. With this approach, unprotected segments ranging from 4 to 37 residues were coupled to aqueous solution to give free peptides up to 54 residues long with high efficiency.

BK virus and a new type of JC virus excreted by HIV-1 positive patients in rural Tanzania

HIV-1 positive patients from Tanzanian villages near Shirati were examined for urinary excretion of the human polyomaviruses JC and BK using the polymerase chain reaction (PCR). BK virus (BKV) was detected in 11 of 23 individuals tested. The BKV DNA sequences were all closely related to prototype Gardner strain and BKV (DUN). In contrast, a new type of JCV, termed Type 3 [or JCV (Shi)], was identified in seven of these same 23 individuals by comparison with Type 1 and Type 2 sequences of the VP1/intergenic/T antigen region of U.S., European and Asian strains. This suggests that JCV and BKV, although closely related, have different evolutionary histories within the African population. The six BKV regulatory regions amplified all showed the archetypal configuration. However, two of the seven JCV regulatory regions showed rearrangements: a small deletion and an inverted repeat. JCV causes a fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML), in about 5% of AIDS patients in Europe and the U.S.A., but only one case has been reported in Africa. Our results suggest that this rarity of PML is not due to the absence of JCV in the African population.

Diagnosis and screening of HIV/AIDS using clinical criteria in Tanzanian adults

The clinical utility of the World Health Organization (WHO) clinical case definition (CCD) of acquired immune deficiency syndrome (AIDS) in Africa, several proposed modifications of the WHO CCD, and two proposed screening algorithms for human immunodeficiency virus (HIV) infection were examined in adult medical inpatients in Dar es Salaam, Tanzania. Sensitivity, specificity, and positive and negative predictive values were determined for the CCDs and screening algorithms. Multivariable analysis identified factors with high accuracy for HIV infection. Of 223 patients enrolled in the study, 95 were seropositive for HIV infection. The WHO CCD and the modified CCDs had low sensitivities (14.7-32.6%) but high specificities (95.3-99.2%) and positive predictive values (83.8-94.7%). The screening algorithms had moderate sensitivities (66.3-77.9%) and poor specificities (46.1-79.7%). Multivariable analysis consistently identified oral candidiasis and lymphadenopathy as the best predictors of HIV infection. Although patients with asymptomatic or early HIV infection may be missed by clinical criteria, in a high prevalence population, AIDS may be diagnosed accurately clinically because of the effect of prevalence on the positive predictive values of the CCDs. Furthermore, selection of patients for HIV serologic testing may be guided by simple combinations of clinical features.

Common virulence factors for bacterial pathogenicity in plants and animals

A Pseudomonas aeruginosa strain (UCBPP-PA14) is infectious both in an Arabidopsis thaliana leaf infiltration model and in a mouse full-thickness skin burn model. UCBPP-PA14 exhibits ecotype specificity for Arabidopsis, causing a range of symptoms from none to severe in four different ecotypes. In the mouse model, UCBPP-PA14 is as lethal as other well-studied P. aeruginosa strains. Mutations in the UCBPP-PA14 toxA, plcS, and gacA genes resulted in a significant reduction in pathogenicity in both hosts, indicating that these genes encode virulence factors required for the full expression of pathogenicity in both plants and animals.

Inhibition of HIV-1 replication and activation of RNase L by phosphorothioate/phosphodiester 2',5'-oligoadenylate derivatives

2',5'-Oligoadenylate (2-5A) derivatives have been designed to act distal to the human immunodeficiency virus-1 (HIV-1)-induced blockade in the 2-5A synthetase/RNase L antiviral pathway. Stereochemical modification of individual internucleotide linkages of the 2-5A molecule was accomplished by phosphoramidite and phosphotriester chemical syntheses. Phosphorothioate/phosphodiester trimer and tetramer 2-5A derivatives revealed differences in the stereodynamics of activation of RNase L and inhibition of HIV-1 replication. The first and second internucleotide linkages are critical for activation of recombinant, human RNase L; A(Rp)ApA, A(Sp)ApA and ApA(Rp)A are agonists (IC50 = 2 x 10(-7), 2 x 10(-6) and 8 x 10(-6) M); ApA(Sp)A is an antagonist. The second and third internucleotide linkages are crucial for activation of murine RNase L; ApA(Rp)A, ApA(Rp)ApA, and ApApA(Rp)A are agonists (IC50 = 5 x 10(-7) M); ApA(Sp)A, ApA(Sp)ApA, and ApApA(Sp)A are antagonists. Inhibition of HIV-1-induced syncytia formation by the phosphorothioate/phosphodiester derivatives is specific for derivatives with substitution at the 2',3'-terminus. ApA(Rp)A, ApA(Sp)A, ApApA(Rp)A, and ApApA(Sp)A are potent inhibitors of HIV-1-induced syncytia formation (80-, 10-, 40-, and 15-fold more inhibitory, respectively, than solvent control). HIV-1 infection results in enhanced uptake and accumulation of ApA(Rp)A and ApA(Sp)A (7- and 10-fold, respectively). These stereochemically modified 2-5A derivatives are taken up preferentially by HIV-1-infected cells and show promise in anti-HIV-1 chemotherapy.

Specificity and formation of unusual amino acids of an amide ligation strategy for unprotected peptides

An important step in the recently developed ligation strategy known as domain ligation strategy to link unprotected peptide segments without activation is the ring formation between the C-terminal ester aldehyde and the N-terminal amino acid bearing a beta-thiol or beta-hydroxide. A new method was developed to define the specificity of this reaction using a dye-labeled alanyl ester aldehyde to react with libraries of 400 dipeptides which contained all dipeptide combinations of the 20 genetically coded amino acids. Three different ester aldehydes of the dye-labeled alanine: alpha-formylmethyl (FM), beta-formylethyl (FE), and beta,beta,beta-dimethyl and formylethyl esters (DFE), were examined. The DFE ester was overly hindered and reacted with N-terminal Cys dipeptides (Cys-X). Interestingly, it also reacted slowly with the sequences of X-Gly where Gly was the second amino acid and the X-Gly amide bond participated in the ring formation. Although the FE ester reacted similarly as the FM ester in the ring formation, the subsequent O,N-acyl transfer was at least 30-fold slower than those of the FM-ester. The FM alpha-formyl methyl ester was the most suitable ester and was reactive with dipeptides of six N-terminal amino acids: Cys, Thr, Trp, Ser, His and Asn. The order and extent of their reactivity were highly dependent on pH, solvent and neighboring participation by the adjacent amino acid. In general, they could be divided into three categories. (1) N-Terminal Cys and Thr were the most reactive.(ABSTRACT TRUNCATED AT 250 WORDS)

[Detection of human papillomavirus in condyloma acuminata tissues]

We used immunohistochemical technique, in situ hybridization and polymerase chain reaction to detect HPV capsid antigen (HPV-Ag) and HPV-DNA sequences in genital condyloma and pseudocondyloma of vulvae tissues. We also observed the relation between HPV distribution in condylomas and their histological changes.

RESULTS

71.4% of condylomas were positive for HPV-Ag with IMHC, 96.5% of condylomas were positive for HPV6/11 DNA with ISH, and 100% of condylomas were positive for HPV6/11/16/18DNA with PCR. Only 21.4% of pseudocondylomas of vulvae were positive for HPV6/11/16/18DNA with PCR. By observing the distribution of labelled HPV-Ag and HPV-DNA, we found a close relation between HPV proliferative infection and the specific changes of condylomas.

Chinese character operating system of traditional Chinese medicine and pharmacology (TCMP)

With the development in research, teaching and literature work in traditional Chinese medicine and pharmacology (TCMP) by means of computers, it has been found that the existing Chinese character operative systems cannot meet the need of carrying out information processing and software development in this field, since these systems do not include many of the common and special terms in TCMP. This makes it inconvenient to exchange academic thoughts in information processing in this field with our colleagues at home and abroad and greatly affects the sharing of the literature data in TCMP. It is therefore necessary to develop a Chinese character operating system applicable to the use of computers in the research of TCMP. Recently, we have developed jointly a Chinese character operating system of TCMP. This system is based on the original GB2312-80 Chinese character international code, to which are added 1,150 Chinese characters commonly used in TCMP. The five-stroke code, which make input possible according to word forms, are used for the input of expanded words. Besides, the system also provides the codes of a number of common names of Chinese materia medica, acupoint names, common terms in traditional Chinese medicine (TCM), TCM disease names, names of classic TCM works, etc. It also provides a convenient character-creating software. We hope that our work will lead to discussions concerning the difficult problems in computer processing of TCMP literature, i.e. the Chinese character.

Sexual behaviour survey in a rural area of northwest Tanzania

OBJECTIVE

Little is known about variations in patterns of sexual behaviour in different countries, cultures, and subpopulations that determine the spread of HIV-1. Quantitative studies are required to improve understanding.

METHODS

To assess reported patterns of sexual behaviour, we administered a standardized questionnaire to 416 men and 498 women aged 15-49 years from a rural population in northwest Tanzania.

RESULTS

Reported levels of sexual activity were highest in men and among younger age groups. The number of sexual partners and number of sex acts per unit of time were strongly correlated: men reported 10 times as many lifetime partners than women. Frequency of sexual partner exchange plateaued earlier in women (by age 25 years) than in men (by age 35 years). For the great majority, age of first intercourse was 15 years or younger; older subjects were older at first intercourse and had fewer lifetime partners than younger subjects.

CONCLUSIONS

This age-related pattern suggests that more recent birth cohorts have behaviour patterns that increase the risk of sexually transmitted infectious agents such as HIV. Preventive education programmes should be targeted at young adults, who adopt higher risk profiles of frequent partner exchange linked with first intercourse at an early age.

Population-based study of HIV-1 infection in 4,086 subjects in northwest Tanzania

A population-based HIV-1 seroprevalence survey of 4,086 individuals, aged 15-49 years, in the North Mara district of Tanzania from rural, periurban, and urban areas, including high-risk (prostitutes, and co-workers) individuals, was performed in 1989 and 1990. The overall seroprevalence was 7.3% (95% confidence interval, 6.5-8.1), with a gradient of seropositivity from high-risk 13.0% (9.1, 16.8), urban 8.8% (7.6, 10.0), periurban 6.5% (4.7, 8.4), to rural 2.6% (1.6, 3.7) subjects. Adjusted for population group, HIV-1 seroprevalence was significantly elevated for men over age 24 and for women 20-34 years old, while age-specific prevalence rates were similar for men and women in the rural area. Recent treponemal infection, measured by the rapid plasma reagin test, was not associated with HIV-1 seropositivity in men or women. These data suggest a growing HIV-1 epidemic paralleling rising rates in other rural areas of Africa distant from areas that have been previously recognized as having high prevalence.

Chest radiography and beta-2-microglobulin levels in HIV-seronegative and HIV-seropositive African patients with pulmonary tuberculosis

To examine the relationship between radiographic features, serum beta-2-microglobulin (beta-2-M) levels, results of sputum-smear microscopy and outcome, we performed a retrospective study of 99 HIV-seropositive and 162 HIV-seronegative patients with pulmonary tuberculosis (TB) in Dar es Salaam, Tanzania. Radiographic features of primary TB were more common and features of postprimary TB less common in HIV-seropositive compared to seronegative patients (50% vs 31%, p < 0.002; and 40% vs 63%, p < 0.001), respectively). HIV infection had a strong independent effect on the beta-2-M levels. Among HIV-infected patients radiographic findings of primary TB were significantly more often associated with beta-2-M levels of > 4 mg/l than features of postprimary TB (71.1% vs 44.4%, p < 0.02). In patients with features of postprimary TB, acid-fast bacilli were more often detected in sputum smears than in patients with primary TB (65% vs 47%, p > 0.05, in HIV-seropositive patients; and 63% vs 31%, p < 0.001) in seronegative patients). The observed mortality was too low to identify radiographic predictors of survival. We conclude that HIV-infected patients with features of primary pulmonary TB are likely in an advanced stage of HIV infection and deserve close supervision during anti-tuberculous therapy.

Two-stage sampling in pharmaceutical applications

In the pharmaceutical industry, some tests for quality assurance before, during and after the manufacture of a drug product involve a two-stage sampling technique. We propose statistical testing procedures in a two-stage sampling problem with large within-class sample sizes. We also derive a two-stage sampling plan by minimizing the expected squared volume (or the generalized variance) of the confidence region related to the test. We present two examples to illustrate the proposed methods.

Purification, characterization and binding interactions of the Chinese-cobra (Naja naja atra) serum antitoxic protein CSAP

The characterization of the single-chain protein in Chinese-cobra (Naja naja atra) blood serum, which yields strong specific protection against the venom of the same snake, is reported. The protein, CSAP (cobra serum antitoxic protein), was purified to electrophoretic homogeneity. Over the pH range 5-9 it formed stable complexes with the neuro- and the cardio-toxin of the snake. The molecular size of the CSAP was estimated to be 70.3 +/- 0.3 kDa. Tryptic hydrolysis of CSAP yielded several peptides that were able to bind to the toxin. The native CSAP maximally bound 8 +/- 1 toxin molecules/molecule. Six tryptic fragments, containing 5-39 residues, were sequenced. The longest of these displayed sequence similarity to rat serum albumin. The protective effect of the CSAP was demonstrated in vivo on mice and in vitro by measurement of the rate of haemolysis. Kinetic and thermodynamic parameters of the binding interactions of the neurotoxin and the CSAP were determined from the rates of displacement of 125I-labelled toxin from its complexes with the CSAP by unlabelled toxin by using a DEAE-cellulose filter assay for CSAP-toxin complexes. The toxin molecules rapidly dissociated from one type of site and slowly from a second. The binding capacity and concentration of the CSAP suffice to explain the protective effect of the latter against the toxin.

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.