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Biomedical subjects

M Jennings

Publications and source records attributed to M Jennings.

At least 37 records · Page 2Linked to original sources
PubMed1996

Octreotide therapy in carcinoid disease.

Octreotide therapy is expensive, but at present it and other somatostatin analogues appear to offer the best opportunity of controlling the symptoms of flushing and diarrhoea. It may also have other properties affecting general well-being. The question of whether it changes tumour growth remains unanswered and there is no convincing evidence that it alters survival. In all published studies the numbers of patients are small and there have been no control groups. However, since no other drug has yet proved effective against flushing, the somatostatin analogues, including octreotide, remain the treatment of choice for the symptomatic control of the carcinoid syndrome. Octreotide is of great therapeutic value pre-operatively and intra-operatively and it is essential that all operating theatres have this drug available for immediate use. Surgical debulking, if feasible, provides the best outcome potential in carcinoid disease. Present evidence suggests that the place of octreotide and other somatostatin analogues is in controlling the symptoms of the disease rather than its progress and in ensuring cardiovascular and respiratory stability during surgical procedures.

Antineoplastic Agents, Hormonal↗
PubMed1995

Passive immunization of rhesus macaques against SIV infection and disease.

To evaluate the role of humoral immunity against simian immunodeficiency virus (SIV), we tested whether passive immunization with plasma from SIVmac251 vaccine-protected or healthy infected animals would protect rhesus monkeys against intravenous infection with ten 50% animal infectious doses of the cell-free homologous virus. The challenge dose of this SIVmac251 virus stock had previously caused persistent infection in all (21 of 21) nonimmunized controls. A plasma pool was obtained from a donor that had been immunized with an inactivated whole SIVmac251 vaccine produced in human T cells. This plasma pool contained low levels of SIVmac binding and neutralizing antibody but had a high titer of antibodies recognizing human cell proteins. Given 4 or 18 hr before intravenous challenge, this plasma completely protected three of eight recipients from infection and delayed virus detection in one recipient. The five unprotected animals had only a transient or undetectable p27 antigenemia and low virus load in their PBMCs, and all survived at least 7 months after infection. By contrast, no protection was observed in 6 monkeys given inactivated, pooled plasma or purified immunoglobulin (Ig) from healthy SIVmac251-infected animals. This plasma pool and the Ig preparation contained high levels of SIV-binding and neutralizing antibody but no reactivity to human cellular components. Five of the six recipients had persistent antigenemia after challenge and four died acutely from simian AIDS in 4-7 months. These studies suggest that passive transfer of antibody to human cellular antigens can confer protection against SIVmac whereas passive transfer of neutralizing antibodies without human cellular antibodies does not protect against the homologous virus and may enhance infection.

Animals↗
PubMed1995

Inhibitory motor seizures: correlation with centroparietal structural and functional abnormalities.

Six adults and 2 children with focal inhibitory motor seizures (ictal paralysis) were evaluated during a 4-year period. Paresthesias at seizure onset occurred during some seizures in all patients, and focal clonic activity followed paralysis in 4. EEG-CCTV recordings of the seizures in 2 patients showed that ictal paralysis coincided with an ictal discharge starting in one centroparietal area. MRI showed centroparietal structural lesions in six patients. One patient with a normal MRI scan had right centroparietal hypometabolism on PET. Inhibitory motor seizures must be differentiated from transient ischemic attacks and migraine. In our patients a centroparietal epileptogenic focus was suggested by neuroimaging studies, and in 2 instances by ictal EEG.

Adolescent↗
PubMed1993

Human immunodeficiency virus type 1 (HIV-1) fusion with model membranes: kinetic analysis and the role of lipid composition, pH and divalent cations.

The kinetics and extent of HIV-1 fusion with model membranes was studied. HIV-1 was labeled with octadecyl rhodamine B chloride, and fusion was monitored continuously as the dilution of the probe into target membranes. The results were analyzed by a mass action model which yielded good simulations and predictions for the kinetics and final extents of fluorescence increase. The model determined the percent of virions capable of fusing and rate constants of fusion, aggregation and dissociation. Ultrastructural analysis of the virus and reaction products by electron microscopy also provided evidence of HIV-1 fusion with membranes lacking CD4. HIV-1 fusion activity depends on the target membrane lipid composition according to the sequence: cardiolipin (CL) > > phosphatidylinositol > CL/dioleoylphosphatidylcholine (DOPC) (3:7), phosphatidic acid > phosphatidylserine (PS), PS/cholesterol (2:1) > PS/PC (1:1), PS/phosphatidylethanolamine (1:1) > DOPC, erythrocyte ghosts. Reduction of pH from 7.5 generally enhances the rate and extent of HIV-1 fusion. Physiologically relevant concentrations of calcium stimulate HIV-1 fusion with several liposome compositions and with erythrocyte ghost membranes. The fusion products of HIV-1 with liposomes consist of a single virus and several liposomes. The mass action analysis revealed that, compared to intact virions, the fusion products show a striking reduction in the fusion rate constant. Like influenza and Sendai viruses, HIV-1 fusion with membranes containing its own envelope glycoprotein(s) is strongly inhibited. Unlike these viruses, HIV-1 fusion is promoted by physiological levels of calcium. HIV-1 fusion with liposomes is qualitatively similar to simian immunodeficiency virus fusion.

Cardiolipins↗
PubMed1993

Adhesion of lymphocytic cells to human trophoblast cells in vitro.

The adherence of lymphocytic MOLT-4/clone 8 cells and normal human peripheral blood mononuclear cells (PBMCs) to primary cultures of term human syncytiotrophoblast has been characterized. Adherence was measured using a fluorescence-based assay in which leukocytic cells were labelled with calcein-AM. Adherence of MOLT cells to syncytiotrophoblast increased in a time-dependent fashion up to about 4 h after which adhesion decreased. Adhesion was detectable at 4 degrees C but was greatly reduced compared to that seen at 37 degrees C. Binding increased linearly as the ratio of MOLT cells to trophoblast was increased. Scanning and transmission electron microscopy of MOLT cell-trophoblast cocultures revealed lymphocytes adherent to the free microvillous surface of the syncytiotrophoblast masses. MOLT cells also adhered to cytotrophoblast but the extent of binding was lower than to syncytiotrophoblast. Normal human peripheral blood mononuclear cells adhered to syncytiotrophoblast. Preincubation of trophoblast cells with trypsin in the presence of calcium had no effect on subsequent adhesion of MOLT cells. However, preincubation of trophoblast cells with trypsin in the absence of divalent cations reduced subsequent adhesion. Adhesion of MOLT cells to syncytiotrophoblast was dependent on magnesium and calcium. These results show for the first time that lymphocytic cells adhere to isolated human syncytiotrophoblast and raise the possibility that this may be an important phenomenon in vivo.

Calcium↗
PubMed1993

Outsourcing: the new age of hospital supply management.

As the healthcare industry faces increasing pressure to identify and cut costs, outsourcing of Central Service functions may become dominant. The authors represent Baxter Healthcare's vision for CS in the next decade, which includes supplying comprehensive case kits containing all the consumable supplies needed for a patient's entire length of stay. The goal is to replace large, on-hand inventories and expensive CS functions with a procedure-based processing, packing and delivery service. The vision is already underway from several vendors. There should be cost savings in picking and replenishment functions currently handled in the OR, repair and CS costs. Hospital personnel may not be replaced, but their functions will change. The arrangement requires long-term thinking, mutual acceptance of risk and the development of trust.

Central Supply, Hospital↗
PubMed1991

Audit of a new appointments system in a hospital outpatient clinic.

OBJECTIVE: To assess the effect of a new appointments system on patients' waiting time. DESIGN: Replacement of an existing system of regularly spaced appointments at 10 minute intervals with one in which the doctor arranged appointments according to his perception of individual patients' requirements, from December 1988 to June 1989. SETTING: One general medical outpatient clinic. PATIENTS: All (181) [corrected] patients under regular review with fixed appointment times during six months; those arriving for blood testing before the start of the clinic and those requiring ambulance transport were excluded. MAIN OUTCOME MEASURES: Mean waiting time (mean of difference between appointment time and start of consultation), maximum waiting time, number of patients, and total duration of clinics. RESULTS: Mean waiting time was reduced by about 30 minutes (from 39.6 to 9.5 mins) over the six months. There was no change in the number of patients attending (mean 15.8 v 15.4) or the duration of the clinics (mean 187 v 160 mins). CONCLUSION: Efficiency was improved by simple adjustment to the appointments system used in the hospital outpatient clinic.

Appointments and Schedules↗
PubMed1991

Cell-mediated infection of human placental trophoblast with HIV in vitro.

In order to investigate how human immunodeficiency virus (HIV) gains entry to the placenta, we have performed in vitro experiments in which highly purified trophoblast cells isolated from term human placentas were examined for their susceptibility to HIV infection. Trophoblast cells were exposed to cell-free HIV-1 for up to 24 h, after which the cultures were monitored by p24 antigen capture assay, reverse transcriptase assay, and electron microscopy for evidence of virus uptake and replication. None was found. In the second series of experiments, trophoblast cells were cocultured with HIV-infected MOLT-4 cells for 24 h, stained using an anti-HIV antibody, and examined by immunofluorescence microscopy. The MOLT cells were strongly positive, as expected, but many trophoblast colonies also showed a punctate staining pattern. Examination of similar cultures using the electron microscope revealed MOLT cells adherent to trophoblast but no evidence of cell-cell fusion. Virions were observed in coated pits at the trophoblast cell surface and in endosomes or multivesicular bodies in the cytoplasm. These observations are consistent with an endocytosis-mediated mechanism of virus entry. Virions were also observed budding from the trophoblast plasma membrane, indicating that these cells can support HIV replication. To our knowledge, these results show for the first time that HIV can infect placental trophoblast cells in vitro. The results suggest that the placenta could become infected with HIV by the interaction of virus-infected maternal lymphocytes with syncytiotrophoblast bordering the maternal blood in the intervillous space.

Female↗
PubMed1991

In vivo administration of tumor necrosis factor-alpha is associated with antiviral activity in human peripheral mononuclear cells.

Tumor necrosis factor-alpha (TNF-alpha) has a spectrum of biologic effects and has been shown to exert antiviral effects in fibroblasts in vitro. The in vivo administration of TNF-alpha (40-160 micrograms/m2 intravenously over 2 hr) and its effects on vesicular stomatitis virus (VSV) replication in peripheral blood mononuclear cells (PBMC) from patients with malignancy was investigated. Blood was obtained before, during, and after infusion. The PBMC were separated and infected with VSV at a multiplicity of infection of 0.005 plaque-forming units/cell and virus yields were determined 72 h later. The TNF-alpha inhibited VSV yields by as much as 99% in a dose-dependent manner with the inhibition initially observed during the first hour of infusion. Despite a rapid reduction in TNF-alpha serum levels, the higher doses still produced antiviral effects 4 hr after the infusion. Sera obtained at identical times had no interferon activity. Human gamma-interferon (25 micrograms/ml) added in vitro augmented the TNF-alpha-induced inhibitory activity in both magnitude and duration. Percentages of lymphocytes and monocytes in peripheral blood were reduced at 4 hr after TNF-alpha administration and the monocyte to lymphocyte ratio was diminished and temporally coincided with the loss of TNF-induced antiviral state. These data suggest that the in vivo administration of TNF has a direct inhibitory activity on VSV replication in human peripheral blood mononuclear cells that was enhanceable by gamma-interferon and possibly monocyte mediated.

Cells, Cultured↗
PubMed1991

SIV vaccine protection of rhesus monkeys.

Rhesus macaques (M. mulatta), immunized with an inactivated whole SIVmac vaccine and muramyl dipeptide or Freund's incomplete adjuvant, were protected against IV challenge infection with 10 animal infectious doses of the homologous virus. The protection in these animals appeared to be complete, with no breakthrough of latent virus infection over a 10-month period. Vaccine protection in this model was correlated generally with a high level of SIVmac envelope antibody by ELISA and immunoblot, high titers of syncytial inhibiting antibody, and, more specifically, with the presence of antibodies binding to a putative V3 loop synthetic peptide of the SIVmac outer envelope. This model can now be used for further identification of the protective epitopes and protective host immune responses as well as for development of novel and better AIDS vaccines.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

SIV, STLV-I and type D retrovirus antibodies in captive rhesus macaques and immunoblot reactivity to SIV p27 in human and rhesus monkey sera.

The prevalence of simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus type 1 (STLV-I), and type D retrovirus (SRV-D) antibodies was determined for 1229 rhesus monkeys (Macaca mulatta) from two research colonies. Serum samples were tested by using enzyme-linked immunosorbent assay (ELISA), immunoblot (IB), and radioimmunoprecipitation assay (RIPA). Seropositive results for the three retroviruses tested were 0 for SIV, 270 (22%) for STLV-I, and 103 (8.4%) for type D retrovirus. Of the rhesus monkey sera, 61 (5.0%) were reactive to SIV gag p27 only, when tested by IB, but were negative when further tested by RIPA. Virus isolation was attempted from cultured peripheral blood mononuclear cells of 35 monkeys whose sera contained only p27 reactivity and none were positive by reverse transcriptase and core antigen assays to detect SIV. No overt clinical signs of immunodeficiency disease or unexplained deaths were evident in either monkey colony. Additionally, 63 of 165 (38%) human sera from various groups (primate center workers, normal donors, health care workers) had weak to moderate IB reactivity only to SIV p27, but 31 of 31 sera tested were negative by RIPA. These sera remained reactive to SIV p27 following absorption with an uninfected cell lysate, after blocking IB strips with various blocking solutions and were reactive to different SIV antigen preparations while remaining negative to human immunodeficiency virus type 1 (HIV-1) by IB and negative to HIV-2 by ELISA. These data underscore the need to adopt criteria for a positive SIV serologic test requiring reactivity against more than one viral gene product. These results also illustrate a potential problem in the testing of human sera for antibodies against simian retroviruses and demonstrate the need for caution in the interpretation of immunoblot results.

Animals↗