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Biomedical subjects

C J Holmes

Publications and source records attributed to C J Holmes.

At least 55 records · Page 3Linked to original sources
PubMed1993

Peritoneal catheters and exit-site practices: toward optimum peritoneal access.

The peritoneal catheter is the CAPD patient's lifeline. Advances in catheter knowledge have made it possible to access the peritoneal cavity safely and maintain access over an extended period of time. Infection at the exit site remains a major problem, a solution for which is being extensively researched. The successful outcome of a catheter in an individual depends on meticulous care and adherence to sound principles of catheter insertion and management. The guidelines provided in this publication represent the consensus based on the extensive experience of several major centers worldwide.

Catheters, Indwelling↗
PubMed1992

Prospective comparison of blood and peritoneal lymphocytes from continuous ambulatory peritoneal dialysis patients.

Although a few studies have analyzed the characteristics of peritoneal lymphocytes from continuous ambulatory peritoneal dialysis (CAPD) patients, there have been no definitive longitudinal investigations comparing peripheral blood lymphocytes (PBL) with peritoneal lymphocytes (PL) from these patients. Therefore, the purpose of this study was to prospectively compare the phenotypes of PBL and PL of CAPD patients and to determine if phenotypic changes occurred from the initiation of CAPD therapy over the subsequent 12 months. Patients were categorized into younger (< 60 years) or older (> 60 years) to determine if age-related factors contributed to differences in lymphocyte phenotypes. Blood and overnight peritoneal dialysate effluents (PDE) were obtained from 18 patients at the initiation of CAPD therapy and for 11 successive months. Fourteen lymphocyte subsets were quantitated using monoclonal antibodies and flow cytometry analysis. CAPD patients had significantly higher percentages of peripheral activated T (CD3+/HLA-DR+) cells and natural killer (CD57+) cells at the beginning of CAPD than normal controls. There were significantly greater percentages of B cells, activated T cells, and suppressor T (CD8+/CD11b+) cells and significantly fewer helper T (CD4+) cells in the PDE as compared with the patients' peripheral lymphocytes. No significant changes were observed over time in the phenotypes of PBL and only one PL phenotype showed significant changes with fluctuating levels of CD4+/CD45RA+ cells with continued peritoneal dialysis. In general, these findings suggest that although both PBL and PL activation is occurring in clinically uninfected patients, the characteristics of lymphocytes are stable over time.

Adult↗
PubMed1991

GABA-synthesizing neurons in the medulla: their relationship to serotonin-containing and spinally projecting neurons in the rat.

GABA-synthesizing neurons were identified in the medulla of the rat by peroxidase-antiperoxidase (PAP) immunohistochemistry for glutamic acid decarboxylase (GAD). Using diaminobenzidine (DAB) either alone or intensified with silver, a relatively large number of GAD-immunoreactive neurons were evident within the reticular formation, raphe nuclei and vestibular nuclei. In all these areas, profuse GAD-immunoreactive varicosities appeared to contact the soma and dendrites of both non-GABA and GABA neurons. These observations suggest that GABA neurons may act as interneurons or local projection neurons within the medulla and accordingly exert a potent inhibitory and/or disinhibitory control on bulbar projection neurons. Within the ventral reticular formation (pars alpha and ventralis of the gigantocellular reticular field) and raphe magnus, large numbers of prominent GAD-immunoreactive neurons resembled in size and morphology and overlapped in distribution the serotonin-immunoreactive neurons of the same regions. However, by sequential double immunostaining utilizing DAB as a chromogen for serotonin (5-HT) and benzidine dihydrochloride (BDHC) for GAD, it was found that GAD-containing neurons were distinct from 5-HT-containing neurons. Following injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the upper cervical spinal cord and combined processing for WGA-HRP (using tetramethylbenzidine [TMB] with cobalt) and immunohistochemistry (with DAB), a contingent of spinally projecting neurons were found to contain GAD. The GAD-immunoreactive reticulo- and raphe-spinal neurons were most frequent within the pars alpha and ventralis of the gigantocellular reticular fields and the raphe magnus, where they were approximately equal in number to the coexistent, but distinct 5-HT spinally projecting neurons. GABA neurons of the medulla may thus contribute directly to the bulbar inhibitory influence upon spinal sensory and motor systems.

Animals↗
PubMed1991

In vitro study of the transfer of cytokine-inducing substances across selected high-flux hemodialysis membranes.

The in vitro transfer of cytokine-inducing substances (CIS) across cellulose triacetate and polyacrylonitrile hollow-fiber high-flux hemodialyzers was studied using culture filtrates of gram-negative bacteria isolated from hemodialysis center environments. With Enterobacter cloacae, no transfer of CIS was seen despite the potent cytokine inducibility and endotoxin content of the challenge solution. In contrast, interleukins 1 and 6 and tumor necrosis factor inducing substances did penetrate both dialyzer types challenged with Pseudomonas aeruginosa culture filtrates containing a high endotoxin content. Transfer was not seen, however, upon dilution of the challenge solution to lower, yet clinically very high levels of endotoxin. These results show that, in vitro, the transfer of CIS across high-flux membranes is critically dependent upon the quality and the quantity of the challenge material employed.

Cytokines↗
PubMed1991

In vitro studies on the microbicidal effectiveness of a xenon-based ultraviolet light device for continuous ambulatory peritoneal dialysis connections.

Mercury vapor sourced ultraviolet light has been used for several years to disinfect connections that are integral to peritoneal dialysis solution delivery systems. This in vitro study evaluated the suitability of xenon flash sourced ultraviolet light as an effective alternative disinfecting agent. Candida albicans was determined to be at least four times more resistant than Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus mitis, and Pseudomonas aeruginosa to ultraviolet radiation generated by both mercury vapor and xenon flash devices. Both ultraviolet devices effectively disinfected transfer set spikes that were inoculated intraluminally with each of these five test microorganisms suspended in a pool of patient dialysis effluent. However, ultraviolet (254 nm) absorbance values of dialysis effluent was found to vary greatly between patients, with the most ultraviolet-opaque effluent significantly reducing the microbicidal effectiveness of the mercury vapor, but not the xenon flash system.

Bacteria↗
PubMed1990

Comparison of peritoneal white blood cell parameters from continuous ambulatory peritoneal dialysis patients with a high or low incidence of peritonitis.

The purpose of this study was to determine if there were differences in selected dialysate white blood cells (WBC) parameters between continuous ambulatory peritoneal dialysis (CAPD) patient groups identified as having a high or low incidence of peritonitis. Parameters studied were total peritoneal WBC yield, percentage and absolute number of various WBC types, and expression of WBC receptors known to be involved in normal host defense mechanisms. WBCs were obtained from peritoneal dialysis effluents (overnight dwell), which were collected at monthly intervals for 6 to 8 months from eight CAPD patients--four with a history of high peritonitis incidence (HPI) (more than two episodes in 12 months) and four with a history of low peritonitis incidence (LPI) (no episodes in more than 24 months). Our results demonstrated that there was no significant difference in the overall mean total cell yields or absolute cell counts between the two patient groups. WBC differentials, although differing somewhat among patients, stayed quite stable over time for an individual patient and there was no significant difference between the two patient groups. Analysis of receptors on the peritoneal WBC was performed using flow cytometry and fluorescein-conjugated chemotactic factors (C5a and fMet-Leu-Phe-Lys), as well as monoclonal antibodies specific for Fc receptors and complement receptors, CR1 (CD35) and CR3 (CD11b). Although there was a trend toward increased expression of all these receptors in the HPI patients, there was no significant difference in the fluorescence intensity of peritoneal neutrophils or macrophages that expressed these receptors between the two patient groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Comparison of large volume culture to other methods for isolation of microorganisms from dialysate.

Patients on continuous ambulatory peritoneal dialysis (CAPD) who reside long distances from a CAPD center often use community medical laboratories to document and manage episodes of peritonitis. We examined the feasibility of using large volume cultures as an alternative to more costly and labor intensive methods and to enhance earlier recovery of microorganisms from these patients. Three methods of processing dialysate from patients on CAPD were compared: (a) inoculation of 400 mL dialysate into a transfer bag (Baxter Healthcare, Inc., Round Lake, IL) containing 100 mL of 5-fold concentrate of trypticase-soy broth: (b) inoculation of 5 mL into each of two Bactec bottles (Johnston Laboratories, Towson, MD): and (c) centrifugation of 50 mL and culture of the sediment without white cell lysis on plated media and two Bactec bottles. Of the 58 specimens cultured, 34 (59%) were positive by one or more methods. Antimicrobial activity was detected in 20/58 (34%) dialysates, which represent 54% of all no-growth cultures. Of the 34 culture-positive specimens, microorganisms were recovered on plated media in 22 (65%); by the centrifugation system in 32 (94%); by the routine Bactec system in 28 (82%); and by large volume culture in 30 (88%). The large volume culture system is an acceptable alternative to the more costly Bactec System and the labor intensive centrifugation method but does not significantly improve recovery of microorganisms.

Bacterial Infections↗
PubMed1989

Application of an empirically derived growth curve model to characterize Staphylococcus epidermidis biofilm development on silicone elastomer.

An in vitro model permitting the development of a staphylococcal biofilm on silicone elastomer is described. Biofilm was determined over time by viable cell quantitation for S. epidermidis strains 8-14B, RP62 and SP2. The log10 viable count data were analysed empirically as a function of time using a negative exponential growth curve model. Although initial colonization and biofilm 72 h cell density of silicone was significantly higher for strain RP62 than SP2, biofilm growth rates did not differ. Strain 8-14B demonstrated a faster biofilm growth rate for the initial 24 h than did RP62 or SP2. The statistical model described was sensitive enough to detect strain differences in biofilm development on silicone elastomer and can be further employed to evaluate the ability of selected biomaterials to retard biofilm development, and the ability of various antimicrobial agents to influence biofilm microbe development.

Biocompatible Materials↗
PubMed1989

Anatomical observations of holoprosencephaly in swine.

In a study of swine congenital anomalies, nine newborn piglets with varying degrees of optic hypotelorism including cyclopia were collected. Nasal and maxillary development were abnormal in all animals regardless of the degree of eye fusion. All animals except one had intact upper lips and hard palates that carried two or three small extopic teeth. The "snout" was only a medial wedge-shaped rudiment projecting from the upper lip. It was distally covered by a typical snout-like glabrous epithelium and carried small vibrissae. Six animals also had a tubular proboscis dorsal to the eye. The distal tip of the proboscis was covered by glabrous epithelium. External nares and nasal passageways, albeit blind-ended, were prominent in the proboscis. The nasofrontal bones projected into the base of the proboscis. Seven piglets were hairless except for fine vibrissae and some eyebrow hairs. All animals had some degree of ear abnormalities, e.g., malposition and absence of external auditory meatus. In all animals the brain was malformed. This abnormality varied from complete absence of the forebrain to an alobar structure with gyri. The remainder of the body of each animal was normal. Developmental anomalies of the nose and eye generally reflect malformations of the forebrain, although the etiology of these defects is unclear. The cyclopia associated with the medial proboscis suggests that both the telencephalon and diencephalon are dysplastic. The presence of glabrous epithelium in two regions on the face suggests that studies of the development of the midline face in the swine will help to elucidate the etiology of the holoprosencephalic series. In this way the pig may prove to be an excellent modeling system for human holoprosencephaly.

Abnormalities, Multiple↗
PubMed1988

Viability of microorganisms in fluorouracil and cisplatin small-volume injections.

The ability of various microorganisms to survive in cisplatin injection or fluorouracil injection in small-volume containers was assessed. Inoculum suspensions of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Pseudomonas cepacia, Candida albicans, or Aspergillus niger were injected into polyvinyl chloride minibags containing 20 mL of either fluorouracil injection 50 mg/mL or cisplatin injection 1 mg/mL in 0.9% sodium chloride injection. All minibags were stored at 25 degrees C for 28 days. Three minibags containing only the sodium chloride solution and 18 minibags containing the sodium chloride solution inoculated with microorganisms served as negative and positive controls, respectively. Samples (1 mL) were obtained within 30 minutes of inoculation and again on days 1, 2, 4, 7, 14, 21, and 28. All microbial species lost viability in both the cisplatin and the fluorouracil admixtures over the study period. In most instances, this loss was more pronounced than that in the positive control solution. Whether the pH of the solutions contributed to this loss of viability was not determined. Under the conditions of this study, admixtures containing cisplatin and fluorouracil did not support rapid growth of microorganisms when stored at room temperature for up to 28 days.

Bacteria↗
PubMed1987

A laboratory method to evaluate formulation effects on the in vitro antimicrobial activity of topical creams and ointments.

A simple and reproducible method is described to assess the effect of formulation on the bactericidal and fungicidal activity of topical antimicrobial agents. The technique involves direct inoculation of test and control articles followed by aliquot sampling, neutralization of active antimicrobial ingredients and enumeration of viable microorganisms by standard methods. Two silver sulphadiazine cream formulations, differing in their aliphatic alcohol content, were evaluated as manufactured and in diluted forms in this manner using three bacterial and one fungal burn wound isolates. Results were analysed by a multivariate analysis of variance to test formulation effects, concentration effects and their interaction over time. The results demonstrate that the antimicrobial activity of both creams is equivalent.

Burns↗
PubMed1987

Effect of vancomycin hydrochloride on Staphylococcus epidermidis biofilm associated with silicone elastomer.

Peritonitis is a major complication of continuous ambulatory peritoneal dialysis. Relapsing peritonitis after the cessation of antimicrobial therapy is frequently reported and often involves Staphylococcus epidermidis. To investigate the potential role of catheter-associated biofilm in the pathogenesis of relapsing peritonitis, we describe an in vitro model permitting the development of an S. epidermidis biofilm on silicone elastomer biomaterial. This model has been used to investigate the ability of vancomycin hydrochloride to kill biofilm-encased organisms by using an antibiotic regimen typical of peritonitis therapy. No significant differences were seen between vancomycin-exposed and control groups in biofilm viable and total cell counts after 10 days. Vancomycin-exposed silicone-associated biofilm populations decreased by only 0.5 log10 CFU/cm2 over the study period. MICs and MBCs for the original S. epidermidis suspension were 3.125 and 6.25 micrograms/ml, respectively. For biofilm homogenate suspensions, MICs were 3.125 micrograms/ml, but MBCs were greater than 400 micrograms/ml. These data indicate that the biofilm organisms associated with an indwelling peritoneal catheter may display a form of tolerance, thereby suggesting one possible mechanism behind relapsing peritonitis.

Humans↗
PubMed1986

Effect of monophosphoryl lipid A on host resistance to bacterial infection.

The ability of monophosphoryl lipid A (MPLA) to enhance nonspecific host resistance to bacterial infections was studied. Mice were treated with MPLA prior to intraperitoneal challenge with Escherichia coli or Staphylococcus epidermidis. Animals received additional MPLA for 2 days postinfection, and survival rates were determined. Ten micrograms of MPLA per mouse significantly improved the survival of animals infected with either bacterial species. Dose-response studies showed significant MPLA-induced protection at doses of 6 micrograms/kg against E. coli challenge and 60 micrograms/kg against S. epidermidis challenge.

Adjuvants, Immunologic↗