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Biomedical subjects

D Persaud

Publications and source records attributed to D Persaud.

At least 19 recordsLinked to original sources
PubMed2004

Torsional method for evaluating hair damage and performance of hair care ingredients.

In this study, we have developed a single hair fiber torsional pendulum method to determine the role of the cuticle and the cortex on torsional properties with respect to fiber cross-sectional area, fiber rigidity, and energy dissipation at 65% RH and in the wet state. Our results demonstrate that in fine diameter fibers with a high cuticle-to-cortex ratio, the cuticula exert a significant effect on the torsional deformation behavior of hair fibers at both normal humidities and in the wet condition. In addition, our data indicate that energy dissipation is confined to fibers with a high cuticle-to-cortex ratio, and the amount of energy dissipated becomes more pronounced with increasing water content. The torsional properties of hair spray-treated fibers suggest that the deposited hair spray film masks the properties of the base fiber and imparts its own dissipative character to the measurement. Since tensile mechanical properties are often used to make claims about the performance of hair care products, we have compared the results obtained from torsional and tensile measurements on over-processed bleached hair fibers conditioned with Polyquaternium-10 and cetyl trimethylammonium bromide (CETAB) to evaluate which method is more advantageous. Our data demonstrate that torsional measurements can distinguish hair care products which reinforce the cuticle from those which affect the cortex, while tensile measurements showed no significant differences.

Biomechanical Phenomena↗
PubMed2001

HIV-1 drug resistance profiles in children and adults with viral load of <50 copies/ml receiving combination therapy.

CONTEXT: The continued release of human immunodeficiency virus type 1 (HIV-1) into plasma at very low levels during highly active antiretroviral therapy (HAART) can be detected using specialized techniques, but the nature and significance of this low-level viremia, especially as related to acquisition of drug resistance mutations, are unclear. OBJECTIVE: To determine genetic resistance profiles of low-level plasma HIV-1 in patients with prolonged viral suppression (<50 copies/mL of plasma HIV-1 RNA) while receiving HAART. DESIGN AND SETTING: Cross-sectional study conducted at a US academic hospital from November 1999 to February 2001 using a novel method for amplification of low levels of viral genomes in plasma. PATIENTS: Eighteen HIV-1-infected patients (7 children and 11 adults), enrolled in a longitudinal study of HIV-1 reservoirs, who had suppression of viral replication while receiving protease inhibitor-containing combination therapy. Two patients (1 adult and 1 child) with less optimal suppression of viral replication were included to assess virus predominating when plasma HIV-1 RNA levels are low but detectable (<1000 copies/mL). Follow-up analyses were conducted in 3 patients. MAIN OUTCOME MEASURE: Detection of drug resistance mutations in clones amplified from low-level plasma virus. RESULTS: Viral sequences were amplified from 8 of the 18 patients with simultaneous plasma HIV-1 measurements of less than 50 copies/mL and from 2 patients with 231 and 50 copies/mL. Clones from 3 treatment-naive patients with less than 50 copies/mL of plasma HIV-1 RNA showed continued release, for as long as 42 months, of wild-type drug-sensitive virus. The 7 patients with prior nonsuppressive therapy, with viral loads below 50 copies/mL and during "blips" to 231 and 64 copies/mL, had only resistance mutations consistent with pre-HAART therapy (although reverse transcriptase inhibitor mutations may have continued to occur). New HAART-related mutations were seen in a control patient with prior viral load levels of about 400 to 1000 copies/mL. For phylogenetic analysis, sequences were available for both resting CD4(+) T cells and plasma HIV for 7 of 10 patients and showed patient-specific clustering of sequences and a close relationship between virus in the plasma and the latent reservoir. CONCLUSIONS: Based on the samples that could be amplified, low-level viremia in children and adults receiving HAART with prolonged suppression of viremia to less than 50 copies/mL of HIV-1 RNA may result primarily from archival, pre-HAART virus, reflecting earlier treatment conditions, and does not appear to require development of new, HAART-selected mutations reflecting partial resistance to therapy. Low-level viremia below 50 copies/mL may represent less of a concern regarding impending drug failure of current HAART regimens. However, the archival drug-resistant virus may be relevant regarding future treatment strategies.

Adult↗
PubMed2000

A stable latent reservoir for HIV-1 in resting CD4(+) T lymphocytes in infected children.

HIV-1 persists in a latent state in resting CD4(+) T lymphocytes of infected adults despite prolonged highly active antiretroviral therapy (HAART). To determine whether a latent reservoir for HIV-1 exists in infected children, we performed a quantitative viral culture assay on highly purified resting CD4(+) T cells from 21 children with perinatally acquired infection. Replication-competent HIV-1 was recovered from all 18 children from whom sufficient cells were obtained. The frequency of latently infected resting CD4(+) T cells directly correlated with plasma virus levels, suggesting that in children with ongoing viral replication, most latently infected cells are in the labile preintegration state of latency. However, in each of 7 children who had suppression of viral replication to undetectable levels for 1-3 years on HAART, latent replication-competent HIV-1 persisted with little decay, owing to a stable reservoir of infected cells in the postintegration stage of latency. Drug-resistance mutations generated by previous nonsuppressive regimens persisted in this compartment despite more than 1 year of fully suppressive HAART, rendering untenable the idea of recycling drugs that were part of failed regimens. Thus the latent reservoir for HIV-1 in resting CD4(+) T cells will be a major obstacle to HIV-1 eradication in children.

Adolescent↗
PubMed2000

Barriers to preventive health practices in women with spinal cord impairments.

Women with spinal cord impairment (SCI) encounter many barriers to receiving satisfactory health care. Problems associated with access to health care decrease the likelihood of health promotion and disease prevention activities for women with disabilities such as SCI. A convenience sample of 28 women was recruited from community settings to participate in this qualitative investigation. This study examined three factors that impact preventative health practices of women with SCI. These are: inadequate knowledge of women with SCI regarding health care risks and health care needs, reliance on caregivers to facilitate preventative health practices, and perceived access to competent health care providers (HCP). Audiotaped interviews were conducted using qualitative data analysis through analytical induction and constant comparison. Saturation of information revealed three common domains: self-management, interactions with caregivers, and interactions with the health care system. Several recommendations are made to facilitate provisions of health promotion and disease prevention activities for women with SCI.

Burnout, Professional↗
PubMed1999

Latent reservoirs for HIV-1.

Combination therapy for HIV-1 infection can reduce viremia to undetectable levels, suggesting that prolonged treatment might eradicate the infection. However, one potential mechanism for viral persistence involves the establishment of a state of latent infection. Recent studies have directly confirmed that HIV-1 establishes a state of latent infection in resting memory CD4(+) T cells in vivo. This reservoir is likely to frustrate current efforts to eradicate the infection with combination therapy.

Journal Article↗
PubMed1999

Cross-national comparison of capitation funding: the American, British and Dutch experience.

In this paper we review the performance of the capitation payment systems of three countries--the Adjusted Average Per Capita Cost (AAPCC) system used in the United States to reimburse Health Maintenance Organizations (HMOs) for insuring Medicare recipients, a somewhat similar system in the Netherlands which reimburses third-party payers for insuring the entire population and a weighted system utilized in Britain for regional funding. Our review revealed significant problems with the current version of the AAPCC formula as there is evidence of the biased selection of beneficiaries and actual losses to Medicare through its use. Furthermore, several studies show that the demographic adjusters utilized in the AAPCC formula are extremely poor predictors of future healthcare utilization relative to the potential of direct and indirect health status measures. The Dutch experience with capitated funding has been similar to that of the United States. While Dutch researchers have built on the work of their American counterparts they acknowledge that further work is needed before a fully functional system is implemented. Britain's weighted system has fulfilled its original mandate to redistribute healthcare resources based on population need but recent changes giving increased influence to age weighting could reverse some of these gains. A number of proposed improvements to these risk adjustment problems were reviewed including the development of diagnostic cost groups, the coexisting hierarchical conditions model and the use of community-rated high-risk pooling. The findings from this study can help others narrow the alternatives they need to consider when thinking of introducing capitation funding or refining already existing systems.

Capitation Fee↗
PubMed1999

Spinal cord impairment: acute transverse myelitis.

Acute transverse myelitis (ATM) is an unusual inflammatory disease involving the entire thickness of the spinal cord. It results in loss of motor and sensory function below the level of injury. The prognosis is variable. The following paper reviews the literature, clinical consideration, and nursing interventions of this puzzling condition.

Adolescent↗
PubMed1998

Human T-lymphocyte transformation with human T-cell lymphotropic virus type 2.

Human T-cell lymphotrophic virus type 2 (HTLV-2), a common infection of intravenous drug users and subpopulations of Native Americans, is uncommon in the general population. In contrast with the closely related HTLV-1, which is associated with both leukemia and neurologic disorders, HTLV-2 lacks a strong etiologic association with disease. HTLV-2 does shares many properties with HTLV-1, including in vitro lymphocyte transformation capability. To better assess the ability of HTLV-2 to transform lymphocytes, a limiting dilution assay was used to generate clonal, transformed lymphocyte lines. As with HTLV-1, the transformation efficiency of HTLV-2 producer cells was proportionately related to the number of lethally irradiated input cells and was comparable to HTLV-1-mediated transformation efficiency. HTLV-2-infected cells were reproducibly isolated and had markedly increased growth potential compared to uninfected cells; HTLV-2 transformants required the continued presence of exogenous interleukin 2 for growth for several months and were maintained for over 2 years in culture. All HTLV-2-transformed populations were CD2 and/or CD3 positive and B1 negative and were either CD4+ or CD8+ populations or a mixture of CD4+ and CD8+ lymphocytes. Clonality of the HTLV-2 transformants was confirmed by Southern blot analysis of T-cell receptor beta chain rearrangement. Southern blot analysis revealed a range of integrated full-length genomes from one to multiple. In situ hybridization analysis of HTLV-2 integration revealed no obvious chromosomal integration pattern.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1996

Medium-term results of experimental stent implantation into the ductus arteriosus.

Balloon dilation is disappointing in maintaining patency of the arterial duct. In neonatal lambs, stent implantation in the arterial duct results in significantly larger ducts with greater pulmonary blood flow than balloon dilation. Little is known, however, about the duration of duct patency after stent implantation. The outcome of stent implantation into the arterial duct in 12 lambs was observed over a period of 1 to 24 months. Stents (Wallstent in 9, Tower stent in 3) were implanted after recanalizing the occluded duct at 2 to 7 days of age. Heparin was given only during the procedure, but no further anticoagulants were used. Angiographic or postmortem evaluations were made at 1, 1.5, 2, 3, 4, 6, 12, 16, and 21 months in a subgroup of 9 lambs who did not undergo reinterventions. The duct was patent in all these except for one studied at 16 months. Neointima initially developed in the center of the stent before extending toward the orifices, eventually burying the metal strands in contact with the wall. From 4 to 6 months onward stenoses were present inside some of the stents. When the stent did not protrude into the aorta, neointima extended over the duct orifice. Metal strands that were not in contact with the duct wall were incompletely covered with endothelial cells, platelets, and fibrin strands, but no thrombi were noted. Late balloon dilation of the stented duct was performed in two lambs increasing the pulmonary artery blood flow. In one lamb the neointimal lining was successfully removed at 14 months with an atherectomy catheter. Stent implantation into the arterial duct can maintain patency up to 21 months and could be considered as an alternative to neonatal systemic to pulmonary artery shunt operations. Neointimal proliferation and stenosis formation, however, is a major limitation that may eventually lead to a reduction in the pulmonary artery blood flow.

Animals↗
PubMed1995

Immunogenicity of synthetic peptides of Haemophilus influenzae type b outer membrane protein P1.

To identify the B- and T-cell epitopes of P1 of Haemophilus influenzae type b, 13 peptides covering 90% of the protein were chemically synthesized. Mouse, guinea pig, and rabbit antisera raised against purified native P1 were tested for their reactivities against the peptides in peptide-specific enzyme-linked immunosorbent assays (ELISAs). Six immunodominant linear B-cell epitopes were mapped to residues 103 to 137, 189 to 218, 248 to 283, 307 to 331, 384 to 412, and 400 to 437 of the mature P1 protein. When P1 peptides were screened for their reactivities with three human convalescent-phase serum specimens, peptides corresponding to residues 39 to 64, 226 to 253, and 400 to 437 reacted strongly with the antisera. Four regions (residues 39 to 64, 226 to 253, 339 to 370, and 400 to 437) contained murine T-cell epitopes. Rabbit antipeptide antisera were tested for their reactivities with the immunizing peptides and P1 protein by ELISA and immunoblots. All anti-P1 peptide antisera except those raised against peptide HIBP1-8 (residues 279 to 312) or HIBP1-8-keyhole limpet hemocyanin conjugate were shown to be specific for their respective immunizing peptides by ELISA. In addition, rabbit antisera raised against the synthetic peptides corresponding to residues 1 to 29, 39 to 64, 103 to 137, 189 to 218, 226 to 253, 248 to 283, 307 to 331, and 400 to 437 of the mature P1 protein recognized the P1 protein from both typeable and nontypeable isolates. These results suggest that these peptides contain epitopes highly conserved among typeable and nontypeable strains of H. influenzae. However, none of the antipeptide antisera have bactericidal activity, nor were they protective against H. influenzae type b in the infant rat model of bacteremia.

Amino Acid Sequence↗
PubMed1995

Time course and cytokine dependence of human T-cell lymphotropic virus type 1 T-lymphocyte transformation as revealed by a microtiter infectivity assay.

Human T-cell lymphotropic virus type 1 (HTLV-1) enhances the growth of T lymphocytes, allowing the generation of T-lymphocyte cell lines. This report describes a limiting-dilution assay system which uses low input numbers of HTLV-1-producing cells for generation of T-lymphocyte cultures. The HTLV-1 transformants generated with this assay system produced high levels of HTLV-1 p24 antigen and required exogenous cytokines for maintenance. Clonal populations of CD4- or CD8-positive HTLV-1 transformants were generated with transformation efficiency rates as high as 78%. An exogenous cytokine is necessary for HTLV-1 T-lymphocyte transformation, and cytokine dependence is the most likely outcome of infection and transformation. HTLV-1 T-lymphocyte transformation can occur in the presence of cytokines other than interleukin-2 (IL-2), such as IL-4 or IL-7. IL-4- or IL-7-dependent HTLV-1 transformants underwent T-lymphocyte mitogenesis in response to their homologous cytokines but proliferated best in the presence of IL-2. Since the receptors for IL-2, IL-4, and IL-7 share the IL-2 gamma chain, this component may be the common element in the signaling pathway for HTLV-1-associated transformation.

CD4-Positive T-Lymphocytes↗
PubMed1994

Efficacy of primary chemoprophylaxis against Pneumocystis carinii pneumonia during the first year of life in infants infected with human immunodeficiency virus type 1.

To evaluate the efficacy of primary chemoprophylaxis in preventing Pneumocystis carinii pneumonia (PCP) in infants with perinatal human immunodeficiency virus-1 infection during the first year of life, we conducted a retrospective chart review of infants with human immunodeficiency virus-1 infection born at New York University Medical Center-Bellevue Hospital Center, in New York. Between March 1989 and March 1993, 24 infants received primary chemoprophylaxis with trimethoprim-sulfamethoxazole in the first year of life and 24 infants did not receive primary prophylaxis. The CD4+ T-lymphocyte counts in the two groups did not differ during the first year of life. The median age at the time of initiation of prophylaxis was 3 months, and the average duration of prophylaxis was 5.5 months. Among the infants who had not received prophylaxis, five cases of PCP were diagnosed at a median age of 5 months; in contrast, no cases of PCP were observed in the infants receiving prophylaxis (log-rank test, p = 0.017). The probability of surviving after 1 year of age was 92% for the children who received prophylaxis and 74% for those who did not (log-rank test, p = 0.035). These data indicate that chemoprophylaxis is highly effective in preventing primary PCP and improving survival time in infants with human immunodeficiency virus-1 infection.

AIDS-Related Opportunistic Infections↗
PubMed1993

Cholestatic hepatitis in children infected with the human immunodeficiency virus.

A distinct clinical syndrome of cholestasis and hepatitis occurred during early infancy in seven infants with perinatally acquired human immunodeficiency virus 1 infection. In five infants hepatitis was the first manifestation of human immunodeficiency virus 1 infection. The median age of onset of hepatitis was 7 months (range, 5 to 10 months). The mean total bilirubin concentration at presentation was 7.4 mg/dl (range, 3.9 to 11 mg/dl), the mean aspartate aminotransferase was 1512 IU/liter (range, 782 to 2960 IU/liter) and the mean alanine amino-transferase 512 IU/liter (range, 92 to 1247 IU/liter). The absolute CD4 count at the time of onset of hepatitis ranged from 191 to 2298 cells/mm3 (mean, 766 cells/mm3). Six of the seven children died within 12 weeks of onset of hepatitis, three as a result of complications of Pneumocystis carinii pneumonia, and two died of complications secondary to cytomegalovirus. In only one infant was the cause of death the direct consequence of liver failure. The seventh infant died 17 months after the onset of hepatitis of dilated cardiomyopathy. No specific etiologic agent has been identified as the cause of cholestatic hepatitis in these infants. In situ hybridization studies to detect human immunodeficiency virus 1 messenger RNA was negative in the liver tissue obtained at biopsy and autopsy in five of the samples tested.

Alanine Transaminase↗
PubMed1992

Neurocysticercosis in an Orthodox Jewish community in New York City.

BACKGROUND AND METHODS: From June 1990 through July 1991, intracerebral infection with the larval stage of the pork tapeworm Taenia solium was diagnosed in four unrelated persons in an Orthodox Jewish community in New York City. None of the patients had eaten pork, and only one had traveled to a country in which T. solium infection was endemic. We investigated this outbreak, screened serum samples from family members and household contacts for antibodies to cysticercosis, and examined stool specimens from household employees for eggs of taenia species. RESULTS: The four patients had recurrent seizures and brain lesions that were radiologically consistent with the presence of cysticerci. The diagnosis was confirmed in two patients by a brain biopsy, and in two by immunoblot assays for cysticercus antibodies. Of 17 immediate family members screened serologically, 7 from two families had cysticercus antibodies. Magnetic resonance imaging of the brain showed cystic lesions in two of the seropositive family members, one of whom had had a seizure. Examinations of six domestic employees from all four households revealed an active infection with taenia species in one and a positive serologic test in another. Since these women had recently emigrated from Latin American countries where T. solium infection is endemic, they were the most likely sources of infection in the members of these households. CONCLUSIONS: A diagnosis of neurocysticercosis should be considered in patients with seizures and radiologic evidence of cystic brain lesions, even in those who do not eat pork and who have not traveled to a country in which T. solium infection is endemic. Recent emigrants from countries in which T. solium infection is endemic should be screened for tapeworm infection in their stools before they are employed as housekeepers or food handlers.

Adolescent↗