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Biomedical subjects

K West

Publications and source records attributed to K West.

At least 55 records · Page 3Linked to original sources
PubMed1998

A common sense review of personal protective equipment. Safety smarts.

Approach the use and need for PPE with common sense, which too many people seem to have set aside because of fear and emotion regarding occupational risk for exposure. As providers, approach emotion with factual educational information received in training programs that focus on medical facts--not fear. Fact: Yes, we risk contracting a disease when we provide health care; however, data clearly shows we run only a low risk. Fact: Because department budgets continue to shrink, we need to purchase wisely. Fact: Sharps injuries represent 80 percent of health care worker exposures. This is where the focus of our attention should be. Fact: PPE use to block the mode of entry for blood/OPIM has been effective for centuries and is scientifically sound. EMS, fire and rescue agencies should focus on creating the proper perspective regarding the risk for disease transmission and utilize a common-sense approach to the use of PPE.

Blood-Borne Pathogens↗
PubMed1998

Recovery rates, serotypes, and antimicrobial susceptibility patterns of salmonellae isolated from cloacal swabs of wild Nile crocodiles (Crocodylus niloticus) in Zimbabwe.

Samples from the cloaca and the ventral skin surface of 67 Nile crocodiles (Crocodylus niloticus) captured in four uninhabited areas at Lake Kariba, Zimbabwe, were cultured for Salmonella. All the skin samples tested negative for Salmonella, whereas 18 of 67 (26.9%) cloacal samples grew Salmonella. Significantly more males than females yielded Salmonella, but no statistically significant correlation among salmonella carriage, body size, and age was recorded. Ten different serotypes of S. enterica belonging to the subspecies enterica, salamae, and diarizonae were isolated. All isolates belonging to subspecies enterica displayed invasive properties in an experimental mouse model and thus exhibited pathogenic potential, whereas none of the other isolates were invasive. In general, isolates were sensitive to a number of commonly used antimicrobials, except for three isolates that were resistant to streptomycin.

Alligators and Crocodiles↗
PubMed1998

A comparison of diagnostic methods for the detection of bovine respiratory syncytial virus in experimental clinical specimens.

Virus shedding was monitored in nasal secretions of 12 calves experimentally infected with bovine respiratory syncytial virus (BRSV) using an antigen capture enzyme-linked immunosorbent assay (ELISA) detecting the nucleoprotein (NP) antigen of BRSV, by a polymerase chain reaction (PCR) amplifying the fusion protein of BRSV, and by a microisolation assay combined with immunoperoxidase staining for the F protein of BRSV. Under the conditions of this study, similar limits of detection and quantitative results were obtained from all three assays. BRSV was detected in nasal secretions of all calves for a minimum of 4 d. Virus shedding began on Day 2 after infection, peaked on Days 3-5, and was cleared in most calves by Day 8. The PCR, and to a lesser extent the ELISA, may detect virus shedding for a longer period after infection than virus isolation, possibly due to neutralization of the virus by rising mucosal antibody. Simulated environmental conditions likely to be experienced during transport of clinical field specimens markedly reduced the sensitivity of virus isolation but had a minimal effect on the results of the NP ELISA. Actual field transport conditions (overnight on ice) had minimal apparent effect on the results of the PCR assay. The less stringent specimen handling requirements, combined with low limits of detection, of both the nucleoprotein ELISA and PCR, indicate either of these assays are more suitable for diagnostic applications than virus isolation.

Animals↗
PubMed1998

Systemic administration of the endothelin-A receptor antagonist TBC 11251 attenuates cerebral vasospasm after experimental subarachnoid hemorrhage: dose study and review of endothelin-based therapies in the literature on cerebral vasospasm.

OBJECTIVE: Increasing evidence implicates endothelin (ET)-1 in the pathophysiological development of cerebral vasospasm. This study examined the ability of TBC 11251 (TBC), a new ETA receptor antagonist, to prevent vasospasm in a rabbit model of subarachnoid hemorrhage (SAH). METHODS: Eighty-five New Zealand White rabbits were assigned to 1 of 10 groups. SAH was induced by injecting autologous blood into the cisterna magna. The treatment groups were as follows: 1) control (no SAH), 2) SAH alone, 3) SAH plus vehicle every 12 hours (BID), 4) SAH plus 5 mg/kg TBC BID, 5) SAH plus 10 mg/kg TBC BID, 6) SAH plus 20 mg/kg TBC BID, 7) SAH plus vehicle at 24 and 36 hours after SAH (24/36), 8) SAH plus 5 mg/kg TBC 24/36, 9) SAH plus 10 mg/kg TBC 24/36, and 10) SAH plus 20 mg/kg TBC 24/36. Animals were killed 48 hours after SAH, by perfusion-fixation, and then basilar arteries were histologically prepared and their cross-sectional areas were measured. RESULTS: The mean basilar artery cross-sectional area was constricted from 0.332 mm2 in the control group to 0.131 mm2 in the SAH alone group, 0.132 in the vehicle 24/36 group, and 0.125 in the vehicle BID group. All groups treated with TBC showed an increase in cross-sectional luminal basilar artery area, relative to the vehicle-treated groups. The 5 mg/kg TBC BID group exhibited a mean basilar artery area of 0.217 mm2, and the 10 mg/kg TBC BID group showed a mean basilar artery area of 0.240 mm2; both groups were statistically improved, compared with the vehicle-treated groups (P < 0.05). No side effects were seen, and there were no differences in the mean arterial pressures between drug- and vehicle-treated groups. CONCLUSION: These findings demonstrate that systemic administration of the ETA receptor antagonist TBC significantly attenuates cerebral vasospasm after SAH, thus providing additional support for the role of ET-1 in vasospasm.

Animals↗
PubMed1998

Assessment of human CD4+ and CD8+ T lymphocyte responses in experimental viral vaccine studies.

The traditional in vitro correlate of immunological protection is the induction by a vaccine of neutralizing antibodies against the virus. It was formerly assumed that protection induced by a vaccine was solely due to neutralizing antibodies. Neutralizing antibodies are potent in the prevention of certain diseases, but virus-specific CD4+ T helper cells aid in the proliferation of specific antigen-triggered B cells to make antibodies. CD8+ T cells are responsible for eliminating virus-infected cells during viral illness, and may act as a second line of defence by becoming activated and eliminating any cells that become infected despite the presence of neutralizing antibodies, for example because of a large challenge dose or antigenic variation at the antibody combining sites. We will briefly review our approaches for measuring human virus-specific CD4+ and CD8+ T cell responses to experimental vaccines. It is critically important to have sensitive, quality controlled assays, including positive controls. There are many potential variables in human T cell assays and pitfalls, which usually result in negative CTL results. Uninterpretable data are to be expected unless adequate preliminary testing has been done to establish sensitive, specific and controlled human antigen specific CD4+ and CD8+ T cell assays.

B-Lymphocytes↗
PubMed1997

Reversible posterior leukoencephalopathy following organ transplantation. Description of two cases.

Although neurologic changes after organ transplantation are often secondary to opportunistic infections or vascular insults, new pathological entities are emerging. We have recently encountered two patients who, a few days after liver and heart transplant, respectively, developed neurological signs and symptoms. Head computerized tomography (CT) scan showed nonenhancing areas of low attenuation, and magnetic resonance imaging (MRI) demonstrated multiple areas of increased signal intensity in the subcortical white matter on T2-weighted images. Stereotactic biopsy of the intracranial lesions was performed in one case. Light microscopic examination demonstrated only mildly edematous white matter. No infectious organisms were observed on light or electron microscopy. In one patient, follow-up MRI 3 months later showed almost complete resolution of the signal abnormalities. Both patients' clinical condition progressively improved. The neuroradiological abnormalities described are consistent with the 'reversible posterior leukoencephalopathy' syndrome associated with cyclosporine toxicity. The pathophysiology of these lesions is unclear; however, it has been suggested that cyclosporine causes an acute ischemic insult secondary to vascular spasm with resultant axonal swelling. This hypothesis is supported by the hypoattenuation seen on CT, the prolonged T2 relaxation seen on MRI, and the absence of contrast enhancement. Concomitant factors (such as hypocholesterolemia or associated therapy with high dose steroids) are important in the development of these lesions as in both of our patients cyclosporine levels were in the normal range. Fortunately, these lesions and the associated manifestations are most often reversible and regress with adjustments of cyclosporine dosage and/or correction of concomitant facilitating factors.

Adolescent↗
PubMed1997

Functional analysis of antibody responses of feedlot cattle to bovine respiratory syncytial virus following vaccination with mixed vaccines.

The antibody response of cattle to bovine respiratory syncytial virus (BRSV) immunization was investigated using 4 different commercially available mixed vaccines. Forty, 5-6 month old, beef calves, randomly assigned to groups of 10, were vaccinated on day 0 and 21 with 1 of 3 inactivated vaccines, (3 groups), or a modified live virus (MLV) vaccine. BRSV-specific antibody responses were measured prior to vaccination and on day 35 by using an enzyme linked immunosorbent assay (ELISA), virus neutralization assay (VN), a fusion inhibition assay (FI); and responses were also measured for their ability to facilitate antibody dependent, complement mediated cytotoxicity (ADCMC) of BRSV infected cells. Sera from day 35 were, in addition, analyzed by use of an IgG1, IgG2 isotype specific ELISA. All vaccines induced significant increases in BRSV specific IgG antibody as measured by ELISA, but only one inactivated and the MLV vaccine induced significant increases in VN titers. Fusion inhibiting antibody titers were low or undetected in calves vaccinated with the inactivated vaccines. Vaccination with modified live virus induced significantly higher titers of fusion inhibiting antibodies, which are considered to be most highly correlated with protection. The VN to ELISA and FI to ELISA ratio of the calves that received MLV vaccine were significantly greater than the calves receiving the 3 inactivated vaccines. Vaccination with MLV induced the highest IgG2/IgG1 ratio. This difference was small, and only significant relative to 2 of the inactivated vaccine groups, which were not significantly different from each other. The higher proportion of IgG2 isotype in the MLV sera was not associated with lower ADCMC, a function not attributed to this isotype. The VN and FI titers, but not the ELISA value of the sera, were most predictive of ADCMC. The inactivation processes apparently alter epitopes and affect the induction of functional antibodies.

Animals↗
PubMed1996

Chromosomal localization in mouse and human of the vasoactive intestinal peptide receptor type 2 gene: a possible contributor to the holoprosencephaly 3 phenotype.

The neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) have been shown to act on a wide range of tissue and cell types, both in the central nervous system and in the periphery. Two distinct receptors for VIP, the VIP receptor type 1 (VIPR1) and the VIP receptor type 2 (VIPR2), have recently been cloned, each of which binds PACAP and VIP with equal affinity. We report here the chromosomal mapping of the human and mouse VIPR2 genes by fluorescence in situ hybridization. The VIPR2 gene maps to the human chromosomal region 7q36.3 and to the F2 region of mouse chromosome 12. Our localization of the human gene places it in the region where the locus for the craniofacial defect holoprosencephaly type 3 (HPE3) maps. Further mapping experiments, carried out on cell lines derived from patients with HPE or HPE microforms and associated 7q deletions, have led us to redefine the distal extent of the HPE3 minimal critical region, originally characterized by Gurrieri et al. (1993, Nature Genet. 3: 247-251.) The VIPR2 gene lies within this new HPE3 minimal critical region. Our results suggest that deletion of the VIPR2 gene is not the sole factor responsible for the HPE3 phenotype. However, it is possible that monosomy at the VIPR2 locus may contribute to the phenotype observed in many cases of HPE3.

Animals↗
PubMed1996

Avoidance of stomas and delayed anastomosis for bowel necrosis: the 'clip and drop-back' technique.

Necrotizing enterocolitis (NEC) and midgut volvulus (MGV) often are associated with extensive bowel necrosis. These cases may require extensive enterectomy and the formation of high or multiple stomas, and frequently are complicated by short bowel syndrome, excessive fluid losses, fistulas, stenosis, and skin breakdown. This report describes a "clip and drop-back" technique, followed by delayed anastomosis performed 48 to 72 hours later. The technique was successful in five severely ill infants (3 NEC, 2 MGV) with extensive necrosis, bowel perforation(s), and peritonitis, who required either a high stoma near the ligament of Treitz or multiple resections and enterostomies. This method removes obvious necrotic perforated bowel, controls contamination, avoids stomas (and their inherent complications in this age group), and preserves bowel length. All five babies survived. The technique is a useful addition to the pediatric surgeon's operative armamentarium in selective cases.

Anastomosis, Surgical↗
PubMed1996

On the use of paramagnetic beads and ferrofluids to assess and eliminate the leukocytic contribution to oxygen radical generation by human sperm suspensions.

PROBLEM: To develop a methodology to determine a) the leukocytic contribution to reactive oxygen species generation by human sperm suspensions and b) the therapeutic value of removing these cellular contaminants. METHODS: Leukocytes were removed with paramagnetic beads or colloidal ferrofluids coated with anti-CD45 antibody. The sperm suspensions were monitored for oxidant generation by chemiluminescence, leukocyte contamination by immunocytochemistry, and fertilizing potential using zona-free hamster oocytes. RESULTS: Percoll -prepared human sperm suspensions exhibited a competence for PMA-induced reactive oxygen species generation which was significantly correlated with leukocyte contamination. However, the purified spermatozoa remaining after paramagnetic bead treatment, also demonstrated an intrinsic capacity for PMA-responsive reactive oxygen species generation and, freed from the oxidative stress created by the leukocytes, exhibited a significantly enhanced capacity for sperm-oocyte fusion. CONCLUSIONS: Although human spermatozoa can generate reactive oxygen species, sperm function is inhibited by the additional oxidative stress created by contaminating leukocytes. Removal of these cells with paramagnetic beads enhances fertilizing potential.

Cell Separation↗
PubMed1996

Kidney transplantation, the Halifax experience.

In the absence of a national kidney sharing system in Canada, virtually all the cadaver kidneys we transplant come from donors within the 4 provinces we serve. Currently the only criteria we use for recipient selection of cadaver kidneys, apart from ABO blood group matching and a negative anti-T-cell crossmatch, are good HLA match and transplant wait-list seniority. All transplant recipients receive CsA-based immunosuppression. Antibody induction is used only for repeat transplants and pediatric transplants. Recipients of first cadaver kidney transplants with zero HLA-DR mismatches have significantly better graft survival than those with mismatches. Graft and patient survival rates for first cadaver transplants continue to improve within the CsA era, and are comparable to those seen in centers routinely using antibody induction and routine sequential quadruple immunosuppression. Chronic graft nephropathy continues to be the most important cause of graft loss after the first year, unchanged over the past 2 decades, followed closely by death with a functioning kidney. The latter is a more important cause of loss in recipients older than age 60, and in recipients of HLA-identical live donor transplants. Repeat cadaver transplant recipients have a 5-year graft survival rate today equivalent to that seen with first cadaver transplants. Graft loss from acute rejection is modest, but kidneys requiring rescue therapy for steroid-resistant rejection have significantly poorer one- and 5-year graft survival and ultimately are lost from rejection. Patients with HLA-identical live-related donor transplants have better long-term survival with CsA than with azathioprine due to a decrease in graft loss from chronic rejection. Pre-transplant sensitization has an adverse effect on graft survival for haploidentical but not HLA identical live-related transplants. Patients over age 60 have equivalent graft survival to younger recipients for at least 7 years, and should not be precluded from receiving transplants by age alone. Prolonged CIT > 24 hours is associated with a significantly increased incidence and duration of ATN and need for dialysis, significantly increased early and late graft loss from acute and chronic rejection respectively, significantly reduced QALY's, and significantly higher early and late costs of transplantation.

Adult↗