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Biomedical subjects

M L Kalish

Publications and source records attributed to M L Kalish.

51 records · Page 3Linked to original sources
PubMed1995

Determination of HIV-1 subtypes in injecting drug users in Bangkok, Thailand, using peptide-binding enzyme immunoassay and heteroduplex mobility assay: evidence of increasing infection with HIV-1 subtype E.

OBJECTIVES: To evaluate the sensitivity and specificity of peptide-binding enzyme immunoassay (PEIA) and heteroduplex mobility assay (HMA) for the determination of HIV-1 subtypes B and E; to determine the proportions of infections due to subtypes B and E over time; and to generate data on DNA sequences of the C2-V3 region of the env genes. METHODS: HIV-1 subtyping was conducted by PEIA and HMA on blood specimens obtained from 97 injecting drug users (IDU) infected with HIV between 1988 and 1993. Genetic sequencing was performed on 84 specimens. RESULTS: Both laboratory methods were highly sensitive and specific for the determination of HIV-1 subtypes B and E. The two tests were complementary; samples which could not be typed by HMA were correctly typed by PEIA and vice versa. While subtype B accounted for 80.4% (78 out of 97) of infections overall, the proportion of new infections due to subtype E increased from 2.6% (one out of 38) in 1988-1989 to 25.6% (11 out of 43) in 1990-1991, and to 43.8% (seven out of 16) in 1992-1993 (chi 2 for linear trend, P < 0.001). CONCLUSIONS: HMA and PEIA are practical, sensitive and specific laboratory methods for the determination of HIV-1 subtypes in Thailand, and may be useful in other geographic areas to define the molecular epidemiology of the global HIV-1 pandemic. Data suggest that the proportion subtype E infections have increased among Bangkok IDU from 1988 through 1993.

Adult↗
PubMed1995

The evolving molecular epidemiology of HIV-1 envelope subtypes in injecting drug users in Bangkok, Thailand: implications for HIV vaccine trials.

OBJECTIVE: To genetically characterize HIV-1 strains in injecting drug users (IDU) in Bangkok, Thailand in 1994, and compare these with strains found earlier in Thai IDU; such information is essential for HIV-1 vaccine development and evaluation. METHODS: Peripheral blood mononuclear cells were collected from 84 IDU attending 14 drug treatment clinics in Bangkok in 1994. DNA was amplified using a nested polymerase chain reaction (PCR) procedure and sequenced directly (without cloning) from the PCR products. The V3 and flanking regions (345 nucleotides) of the env gene were analyzed using a neighbor-joining tree. RESULTS: Only one (1%) strain was a typical subtype B virus, 69 (82%) were genetically distinct subtype B' viruses (Thai B), and 14 (17%) were subtype E strains (Thai A). Persons with recently acquired infection were more likely to have subtype E viruses (P < 0.001) than those in our 1991 survey, who were more likely to have subtype B' viruses. Pairwise intra-subtype differences within subtypes E and B' were 5.3 and 4.3%, respectively, compared with 3.4 and 3.5% among strains collected in 1991 in Thailand. CONCLUSION: The genetic diversity within subtypes B' and E in Thailand and the proportion of new infections due to subtype E viruses among Bangkok IDU are increasing significantly. These data highlight the importance of monitoring the molecular epidemiology of HIV-1 in populations being considered for HIV-1 vaccine trials.

AIDS Vaccines↗
PubMed1994

Lack of HIV transmission in the practice of a dentist with AIDS.

OBJECTIVE: To determine whether dentist-to-patient or patient-to-patient transmission of human immunodeficiency virus (HIV) occurred in the practice of a dentist who had the acquired immunodeficiency syndrome (AIDS). DESIGN: Retrospective epidemiologic investigation supported by molecular virology studies. SETTING: The practice of a dentist with AIDS in an area with a high AIDS prevalence. PARTICIPANTS: A dentist with AIDS, his former employees, and his former patients, including 28 patients with HIV infection. MEASUREMENTS: Identification of potential risks for acquisition of HIV infection, genetic relatedness among HIV strains, and infection-control practices. RESULTS: A dentist with known behavioral risks for HIV infection, who was practicing in an area of Miami, Florida, that had a high rate of reported AIDS cases, disclosed that he frequently did invasive procedures and did not always follow recommended infection-control procedures. Of 6474 patients who had records of receiving care from the dentist during his last 5 years of practice, 1279 (19.8%) were known to have been tested for HIV infection and 24 of those (1.9%) were seropositive. Four other patients with HIV infection were identified through additional case-finding activities. Of these 28 patients with HIV infection, all but 4 had potential behavioral risk factors for infection. Phylogenetic tree analysis of HIV genetic sequences from the dentist and 24 of the patients with HIV infection showed an absence of strong bootstrap support for any grouping and therefore did not indicate that the virus strains were linked. CONCLUSIONS: Despite identifying numerous patients with HIV infection, we found no evidence of dentist-to-patient or patient-to-patient transmission of HIV during dental care. Our findings are consistent with those of all previous studies in this area, with the exception of one that did identify such transmission.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Idiosyncratic errors in visually directed reaching.

Subjects reaching with their eyes closed to visually presented targets missed their targets by an average of 4% of arm length; significant variation in the direction and magnitude of error arose from target location and idiosyncratic sources. The errors were largely unaffected by extreme variation in the arm's starting location. These data lend support to models of sensorimotor learning that focus on associations between postures and hand locations, but do not confirm a leading example of the class, exemplified by Kuperstein's (1988) circular reaction model.

Journal Article↗
PubMed1994

Antigenic variation and serotyping of HIV type 1 from four World Health Organization-sponsored HIV vaccine sites. WHO Network for HIV Isolation and Characterization.

Serologic reactivities of serum or plasma from 55 HIV-1 subjects in four countries--Brazil, Rwanda, Thailand, and Uganda--were examined by V3 peptide immunoassay. Forty-seven (85.5%) of the 55 specimens tested positive to the homologous peptide. A strong correlation between serotype (i.e., pattern of serologic reactivity with a panel of peptides) and genotype was not found. However, the V3 peptide immunoassays may be useful for epidemiologic studies to trace the distinctive HIV-1 strains from different geographic regions of the world. The serology data obtained may be useful for the development of effective V3-based vaccines.

AIDS Vaccines↗
PubMed1994

Biological, serological, and genetic characterization of HIV-1 subtype E isolates from northern Thailand.

Twenty-three HIV-1 isolates were recovered from PBMCs from 26 HIV-1-seropositive individuals in northern Thailand. The viruses grew readily in human PBMCs but only 7 of 17 (41.2%) and 5 of 17 (29.4%) replicated and only at a low level in primary macrophages and in established T cell lines, respectively. By immunoblot assays, sera from Thai subjects were strongly reactive with gp120 from a Thailand isolate, moderately reactive with a Rwandan isolate, and weakly reactive with a North American strain. These three viruses represent, respectively, examples of subtypes E, A, and B as classified by the sequences of the envelope region. Serological assays indicated that broadly reactive rather than type-specific neutralizing activity was detected among these northern Thai sera. The majority of the sera (approximately 75%) neutralized a representative Thailand isolate and the Rwanda isolate but only 55% neutralized the North American strain. However, the difference was not statistically significant. The genetic analyses indicated that nearly all the Thai isolates were highly homogeneous and distinct from the North American/European consensus sequence (subtype B); they belong to subtype E. This is the first report providing biological, serological, and genetic characterization of HIV-1 strains from Thailand. The findings suggest these viruses were recently introduced into the country and that serological evaluation of viral strains needs to be considered along with genetic subtyping when developing an HIV-1 vaccine.

Adult↗
PubMed1994

Characterization of human immunodeficiency virus type 1 isolates from children in Romania: identification of a new envelope subtype.

Human immunodeficiency virus type 1 (HIV-1) isolates recovered from infected children in Romania were characterized for their biologic, serologic, and molecular properties. The isolates were from subjects in different clinical states, and all showed cytopathic properties in peripheral blood mononuclear cells and varying kinetics of replication. The isolates grew to varying titers in macrophages and established T cell lines. Serologic evaluation with Romanian sera indicated stronger antibody response to the gp120 of Romanian isolates than to the envelope protein of HIV-1 isolates from other countries. Although there was cross-neutralization among the Romanian isolates, no substantial activity was noted against HIV-1 prototype strains from the United States, Africa, and Thailand. Genetic analysis of the envelope C2-V3 region strongly suggests that the Romanian isolates are a subtype distinct from those assigned to other HIV-1 strains analyzed to date. This finding raises questions about the origin of HIV-1 in Romania.

Amino Acid Sequence↗
PubMed1993

Independent introduction of two major HIV-1 genotypes into distinct high-risk populations in Thailand.

To investigate the genetic heterogeneity and epidemiological distribution of human immunodeficiency virus type 1 (HIV-1) in Thailand, we determined proviral sequences for 63 HIV-1-infected patients in various risk groups from all over the country between April and July, 1991. Two distinct genotypes of HIV-1, A and B, were found to segregate by mode of transmission. Of 29 sexually infected patients, 25 (86%) had HIV-1 of genotype A and 4 (14%) had genotype B. Among 29 injecting drug users, probably parenterally infected, only 7 (24%) had genotype A and 22 (76%) had genotype B. This segregation is unlikely to have arisen by chance (p < 0.001). No patient was found to have dual infection. Nucleotide divergence averaged 3.4% among genotype-A-infected patients and 3.5% among genotype-B-infected patients, but 22.0% between the genotypes. 37 of 40 isolates (both genotypes) had the GPGQ tetrapeptide at the tip of the V3 loop, which is common in African HIV-1 strains but rare in North American and European strains, where the GPGR motif predominates. These findings suggest that the waves of HIV-1 infection in injecting drug users and in sexually infected patients in Thailand may not be epidemiologically linked. The nucleotide divergence data point to the separate introductions of the two genotypes in Thailand. Further studies in Thailand and neighbouring countries will be useful in the design and selection of candidate HIV vaccines.

Amino Acid Sequence↗
PubMed1993

Genetic diversity of human immunodeficiency virus type 1 strains in Kinshasa, Zaire.

The envelope (env) gene of human immunodeficiency virus type 1 (HIV-1) was amplified by polymerase chain reaction (PCR) from the peripheral blood mononuclear cells (PBMCs) of 14 HIV-1-infected women from Kinshasa, Zaire. Amplified DNA was directly sequenced with a primer specific for the HIV-1 env C2 region. The predicted amino acid sequences for the C2-V3 region for the 14 specimens are presented. The tetrapeptide sequence, GPGQ, located at the crown of the V3 loop, is conserved in all specimens. The same tetrapeptide sequence is present in the Zairian isolate MAL, but not in other published Zairian isolates (Z6, ELI, Z321, JY1, and NDK). Sequence comparison of the env C2-V3 region among the 14 specimens from Kinshasa revealed a 9-25% range of nucleotide divergence, with an average of 16%. Divergence between the 14 specimens and the Zairian isolates MAL, Z6, ELI, Z321, JY1, and NDK ranged from 13 to 31%. A range of 18-28% nucleotide sequence divergence was demonstrated between the 14 Kinshasa specimens and the North American isolate MN. These results demonstrate the importance of examining HIV-1 samples from diverse geographic origins in the development of effective HIV-1 vaccines.

Amino Acid Sequence↗
PubMed1993

Genetic heterogeneity of the V3 region of the HIV-1 envelope glycoprotein in Brazil. Brazilian Collaborative AIDS Research Group.

OBJECTIVE: To examine the genetic heterogeneity of the V3 region of HIV-1 gp120 from 22 Brazilian HIV-1 specimens. DESIGN: Genetic heterogeneity was examined by DNA sequencing of the C2 V3 region of the HIV-1 envelope (env) gene from polymerase chain reaction (PCR)-amplified HIV-1 DNA. Deduced amino-acid sequences were compared to determine the extent of amino-acid conservation among the Brazilian specimens. Genetic similarity among and between the Brazilian specimens and other previously published HIV-1 isolates was analyzed by principal co-ordinate and DNA parsimony methods. METHODS: A 282 base pair (bp) region of a 1.5 kilo (k) bp PCR-amplified HIV-1 env fragment was sequenced by a Taq dye-labeled primer cycle sequencing reaction. Nucleotide sequences were used to analyze inter-specimen relationships based on overall nucleotide sequence similarity and DNA parsimony principles. RESULTS: Amino-acid comparison showed that 15 of the 35 (43%) residues of the V3 loop were conserved among the Brazilian specimens. Nine of the 22 (40%) Brazilian specimens contained the North American-European GPGR tetrapeptide motif, while eight (36%) contained the GWGR motif, previously reported in Japanese isolates. Principal co-ordinate analysis demonstrated that 19 of the 20 examined Brazilian HIV-1 specimens were more similar to North American and Haitian isolates than to African isolates. Similar results were also obtained by DNA parsimony analysis. CONCLUSION: The majority of the Brazilian specimens examined are more genetically related to North American and Haitian HIV-1 isolates than to African isolates. This finding and the presence of a GWGR V3 loop motif in some Brazilian isolates may be important for vaccine development.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Effect of adjuvant formulations on the selection of B-cell epitopes expressed by a malaria peptide vaccine.

Because subunit vaccines may create artificial epitopes, the goal of this study was to concentrate the immune response toward protective epitopes contained in a peptide, [(NAGG)5]Y. This peptide consisted of five repeat sequences of the immunodominant epitope of the circumsporozoite protein of the simian malaria parasite Plasmodium cynomolgi and a terminal tyrosine. It was conjugated to bovine serum albumin and mixed with various adjuvant formulations, including block copolymers L121, L141, L180.5 and a lipopolysaccharide (LPS). Outbred mice were vaccinated with seven vaccine formulations. Postvaccination sera from each group of mice were then pooled, and antibody responses against peptide [(NAGG)5]Y or (NAGG)5 were tested in an enzyme-linked immunosorbent assay and against sporozoites of P. cynomolgi in an indirect fluorescent antibody assay. Although all groups elicited a high antibody response to the peptide [(NAGG)5Y], the presence of the tyrosine induced a different antibody response to the peptide (NAGG)5, and formulations containing LPS alone did not induce an antibody response to either (NAGG)5 or P. cynomolgi sporozoites. The formulation including both LPS and the copolymer L121 was the only one to inhibit the development of P. cynomolgi sporozoites in rhesus monkey hepatocytes by 50%. These results suggest that vaccine formulations influence B-cell epitope selection.

Animals↗
PubMed1991

Murine IgG isotype responses to the Plasmodium cynomolgi circumsporozoite peptide (NAGG)5. I. Effects of carrier, copolymer adjuvants, and lipopolysaccharide on isotype selection.

The tandem repeat peptide of the circumsporozoite protein of Plasmodium cynomolgi, (NAGG)5, conjugated to BSA or Salmonella flagella, was injected into mice with block copolymer and other adjuvants. The flagella carrier preferentially stimulated IgG2a antibodies to (NAGG)5 that constituted as much as 85% of the total IgG antibody whereas the BSA carrier stimulated as much as 98% IgG1. The distribution of isotypes of antibody to (NAGG)5 was also modified by using the copolymer adjuvants L121 or L141, either alone, or especially in combination with a nontoxic LPS. L121 or L141 increased the proportion of IgG2a and IgG2b antibodies to (NAGG)5 after immunization with (NAGG)5-BSA whereas LPS stimulated further increases in IgG2 antibodies (up to 69% of the total IgG). The hapten density, physical form of emulsion, and route of immunization further affected the isotypes produced in this study.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1991

On the sufficiency of the velocity field for perception of heading.

All models of self-motion from optical flow assume the instantaneous velocity field as input. We tested this assumption for human observers using random-dot displays that simulated translational and circular paths of movement by manipulating the lifetime and displacement of individual dots. For translational movement, observers were equally accurate in judging direction of heading from a "velocity field" with a two-frame dot life and a "direction field" in which the magnitudes of displacement were randomized while the radial pattern of directions was preserved, but at chance with a "speed field" in which the directions were randomized, preserving only magnitude. Accuracy declined with increasing noise in vector directions, but remained below 2.6 degrees with a 90 degrees noise envelope. Thus, the visual system uses the radial morphology of vector directions to determine translational heading and can tolerate large amounts of noise in this pattern. For circular movement, observers were equally accurate with a 2-frame "velocity field", 3-frame "acceleration" displays, and 2-frame and 3-frame "direction fields", consistent with the use of the pattern of vector directions to locate the center of rotation. The results indicate that successive independent velocity fields are sufficient for perception of translational and circular heading.

Humans↗