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Biomedical subjects

S M Ray

Publications and source records attributed to S M Ray.

At least 19 recordsLinked to original sources
PubMed2001

Effect of dissolved organic matter on the uptake of trace metals by American oysters.

To examine the effects of dissolved organic matter on metal bioavailability, uptake of trace metals (Cd, Co, Hg, Cr, Ag, Zn) by American oysters (Crassostrea virginica) was compared between treatments with different dissolved organic carbon (DOC) concentrations and contrasting low molecular weight (LMW, 1 kDa) and high molecular weight (HMW, 1 kDa-0.2 micron) DOC fractions, using radiotracer techniques and short-term exposure experiments. Uptake rate constants (mL g-1 h-1) of metals, in general, increased with increasing DOC concentrations, with an initial decrease at lower DOC concentrations. Oyster dry weight concentration factors (DCF, mL g-1), determined at the end of exposure experiments (8 h), also increased for Cd, Co, Cr, Ag, and Zn, but decreased for Hg, with increasing DOC concentrations. Changes of metal uptake rate constants and DCF values with DOC concentration suggest that metal uptake pathways by American oysters vary from predominantly uptake (by diffusion of neutral) of free ionic, inorganically complexed, and LMW organic ligand complexed metals at very low DOC concentration to direct ingestion and digestion of HMW or colloidally complexed metals at higher DOC concentrations. Measured partition coefficients (Kc) between dissolved and colloidal phases were comparable between metals, ranging from 10(5.12) to 10(5.75) mL g-1. However, DCF values and uptake rate constants differed considerably between metals, with the highest DCF values and uptake rate constants found for B-type metals, e.g., Ag, Hg, Zn, and Cd, and the lowest ones for several intermediate-type metals (e.g., Co, Cr). Metal types and thus the interaction of metals with organic ligands, such as strong complexation of B-type metals with S-containing organic ligands, may play an important role in the bioavailability and toxicity of metals to aquatic organisms. Differences in metal uptake in contrasting LMW and HMW DOC treatments suggest a generally depressed bioavailability of colloidally complexed metals at low DOC concentration (0.5 ppm) but a generally enhanced uptake at higher DOC concentrations.

Animals↗
PubMed2000

The influence of the composition of the nursing staff on primary bloodstream infection rates in a surgical intensive care unit.

OBJECTIVES: To determine the risk factors for acquisition of nosocomial primary bloodstream infections (BSIs), including the effect of nursing-staff levels, in surgical intensive care unit (SICU) patients. DESIGN: A nested case-control study. SETTING: A 20-bed SICU in a 1,000-bed inner-city public hospital. PATIENTS: 28 patients with BSI (case-patients) were compared to 99 randomly selected patients (controls) hospitalized > or =3 days in the same unit. RESULTS: Case- and control-patients were similar in age, severity of illness, and type of central venous catheter (CVC) used. Case-patients were significantly more likely than controls to be hospitalized during a 5-month period that had lower regular-nurse-to-patient and higher pool-nurse-to-patient ratios than during an 8-month reference period; to be in the SICU for a longer period of time; to be mechanically ventilated longer; to receive more antimicrobials and total parenteral nutrition; to have more CVC days; or to die. Case-patients had significantly lower regular-nurse-to-patient and higher pool-nurse-to-patient ratios for the 3 days before BSI than controls. In multivariate analyses, admission during a period of higher pool-nurse-to-patient ratio (odds ratio [OR]=3.8), total parenteral nutrition (OR=1.3), and CVC days (OR=1.1) remained independent BSI risk factors. CONCLUSIONS: Our data suggest that, in addition to other factors, nurse staffing composition (ie, pool-nurse-to-patient ratio) may be related to primary BSI risk. Patterns in intensive care unit nurse staffing should be monitored to assess their impact on nosocomial infection rates. This may be particularly important in an era of cost containment and healthcare reform.

Case-Control Studies↗
PubMed1999

Tuberculosis in the inner city: impact of a continuing epidemic in the 1990s.

Tuberculosis cases have recently declined in the United States, renewing interest in disease elimination. We examined the epidemiology of tuberculosis from 1991 through 1997 at an inner-city public hospital and assessed population-based tuberculosis rates by ZIP code in the 8 metropolitan Atlanta counties. During the 7 years, 1378 new patients had tuberculosis diagnosed at our hospital (mean, 197 patients/year), accounting for 25% of tuberculosis cases in Georgia. Coinfection with human immunodeficiency virus (HIV) was common, but a significant decrease in the proportion of HIV-infected patients with tuberculosis was noted over time. Most patients were members of a minority group (93%) and were born in the United States (96%). Two inner-city ZIP code areas had annual tuberculosis rates >120 cases per 100,000 persons, and 8 ZIP code areas had annual rates of 47-88 cases per 100,000 persons between 1993 and 1997, compared with the annual national average of 8.7 cases per 100,000 persons. Our hospital continues to care for large numbers of tuberculosis patients, and rates of tuberculosis remain high in the inner city. These data mandate a concentration of efforts and resources in urban locations if tuberculosis control and elimination is to be achieved in the United States.

Female↗
PubMed1999

Epidemiology of device-associated infections related to a long-term implantable vascular access device.

OBJECTIVE: To examine risk factors for, and determine the incidence of, device-associated infections among patients with an implantable vascular access device. SETTING: Grady Health System, including a 1,000-bed, inner-city, public, teaching hospital and human immunodeficiency virus (HIV), oncology, and sickle cell clinics in Atlanta, Georgia. PATIENTS: 123 consecutive patients who received a PAS-Port implantable venous access device between January 1 and June 30, 1995. DESIGN: Retrospective cohort study with follow-up > or = 1 year following device implantation. RESULTS: Underlying illnesses included HIV infection in 66 patients (median CD4 count, 24.4 cells/mm3), malignancy in 51, and sickle cell disease in 6. Mean age of patients was 43.7 years, 50% were male, and 74% were black. Thirty-one (25%) of 123 patients developed a primary or device-associated bloodstream infection (BSI), and 3 of the 31 patients experienced two separate episodes of infection. The overall rate of infection was 1.23 primary BSIs per 1,000 device days. Patients with cancer had a lower rate of infection than those with HIV infection, but the difference was not statistically significant (0.96 vs 1.50 BSIs/1,000 device days; relative risk, 0.58; 95% confidence interval, 0.27-1.26). Subgroup analysis of patients with different malignancies indicated that infection rates differed according to type of cancer, and there was a trend for heterogeneity across the different cancer strata (P=.06). Gram-positive pathogens accounted for 60% of the pathogens recovered. Six (19%) of 31 patients who developed an infection did so within the first 14 days after implantation. In 11 (32%) of the 34 BSIs, the port required removal; two patient deaths were attributed to device-associated bacteremias (0.072 deaths/1,000 device days). CONCLUSIONS: Approximately one fourth of patients who had a vascular access device implanted developed a primary BSI, but the overall infection rate (per 1,000 device days) was relatively low, even among those with HIV infection. Primary BSI rates in patients with vascular access devices appeared to differ according to the specific underlying illness.

Adult↗
PubMed1997

Nosocomial exposure to parvovirus B19: low risk of transmission to healthcare workers.

OBJECTIVE: To evaluate the risk of nosocomial transmission of parvovirus B19 (B19) infection to healthcare workers (HCWs) exposed to patients with transient aplastic crisis (TAC) caused by acute B19 infection. DESIGN: Cohort study. SETTING: 1,000-bed, urban teaching hospital in Atlanta, Georgia. PARTICIPANTS: Eighty-seven exposed HCWs who cared for two patients with TAC prior to the time they were isolated and a comparison group of 88 unexposed HCWs from wards or clinics where the patients did not receive care. INTERVENTION: Self-administered questionnaire on hospital contact with index patients, B19 community risk factors, and signs and symptoms suggestive of B19 disease. Serology for B19-specific IgM and IgG antibodies measured by antibody-capture enzyme-linked immunosorbent assay. RESULTS: 1 (3.1%) of the 32 nonimmune exposed HCWs had serologic evidence of recent B19 infection compared to 3 (8.1%) of the 37 nonimmune HCWs in the comparison group (P = .6). In a subgroup analysis of exposed HCWs who cared for index patients during the time when the virus load was expected to be greatest, a recent infection rate of 5.8% (1/17) was found among nonimmune HCWs. CONCLUSIONS: The finding of similar rates of recent infection in nonimmune exposed and unexposed HCWs suggests that transmission to HCWs did not occur, despite failure to place the patients in isolation at the onset of hospitalization.

Adolescent↗
PubMed1997

Pollen tube guidance by the female gametophyte.

In flowering plants, pollen grains germinate on the pistil and send pollen tubes down the transmitting tract toward ovules. Previous genetic studies suggested that the ovule is responsible for long-range pollen tube guidance during the last phase of a pollen tube's journey to the female gametes. It was not possible, however, to unambiguously identify the signaling cells within an ovule: the haploid female gametophyte or the diploid sporophytic cells. In an effort to distinguish genetically between these two possibilities, we have used a reciprocal chromosomal translocation to generate flowers wherein approximately half the ovules do not contain a functional female gametophyte but all ovules contain genotypically normal sporophytic cells. In these flowers, pollen tubes are guided to the normal but not to the abnormal female gametophytes. These results strongly suggest that the female gametophyte is responsible for pollen tube guidance, but leave open the possibility that the gametophyte may accomplish this indirectly through its influence on some sporophytic cells.

Arabidopsis↗
PubMed1995

Preventing the nosocomial transmission of tuberculosis.

OBJECTIVE: To study the efficacy of expanded tuberculosis infection control measures consisting primarily of administrative controls. DESIGN: Descriptive case series. SETTING: University-affiliated, inner-city hospital. INTERVENTIONS: Introduction of expanded tuberculosis infection control measures (including an expanded respiratory isolation policy). MEASUREMENTS: The number of tuberculosis exposure episodes and skin test conversion rates of health care workers were measured before and after implementation of expanded infection control measures. Tuberculosis exposure episodes (the number of patients who were not placed in respiratory isolation at admission but who subsequently had a diagnosis of acid-fast bacilli smear-positive pulmonary tuberculosis during that admission or within 2 weeks of discharge) were compared for two time periods: the 8 months before and the 28 months after implementation of infection control measures. Tuberculin skin test conversion rates among health care workers were evaluated during a 2.5-year period. RESULTS: After expanded infection control measures were implemented, the number of tuberculosis exposure episodes decreased from 4.4 per month (35 episodes among 103 patient admissions for potentially infectious tuberculosis over 8 months) to 0.6 per month (18 episodes among 358 patient admissions for smear-positive pulmonary tuberculosis over 28 months) (odds ratio, 9.72; 95% CI, 4.99 to 19.25 [P < 0.001]). The cumulative number of days per month that potentially infectious patients with tuberculosis were not in isolation decreased from 35.4 to 3.3 (P < 0.001). A concomitant decrease in tuberculin skin test conversion rates in health care workers was seen; 6-month tuberculin skin test conversion rates decreased steadily from 3.3% (118 conversions in 3579 health care workers; 1/92 to 6/92), 1.7%, 1.4%, 0.6%, to 0.4% (23 conversions in 5153 workers [1/94 to 6/94]) (P < 0.001). CONCLUSIONS: Infection control measures effectively prevented nosocomial transmission of tuberculosis to health care workers. Administrative controls appear to be the most important component of a tuberculosis infection control program and should be the first focus of such a program, especially at public hospitals, where resources are most likely to be limited.

Adult↗
PubMed1995

Alpha 1-adrenergic receptor antagonist blocks acute cocaine action on the compound action potential of the auditory nerve in the chinchilla.

Acute systemic cocaine injection is known to significantly decrease the compound action potential (CAP) amplitude of the auditory nerve. In an attempt to elucidate the mechanism underlying this phenomenon, the present study investigated the influence of prazosin, an adrenergic alpha 1-receptor antagonist, on the effect of cocaine on the CAP. Amplitude-intensity functions at 1 and 8 kHz were obtained before and after treatment with cocaine (experimental group) or saline (control group) in prazosin pretreated subjects. The characteristic reduction in CAP amplitude after an acute cocaine injection was blocked by 0.05 mg/kg prazosin. When subjects were re-injected with cocaine or saline one h after prazosin, the reduction in CAP amplitude following cocaine injection had recovered.

Adrenergic alpha-Antagonists↗
PubMed1991

Differential effects of atrial natriuretic peptide infusion at physiological doses in different postures in humans.

To evaluate potential physiological actions of atrial natriuretic peptide (ANP) in humans, normal male volunteers were studied in the supine and head-up tilt positions both in the absence and presence of an ANP infusion at a rate which increased plasma ANP levels to ranges observed during physiological stimuli such as volume expansion. Infusion of ANP in the supine position provoked a significant natriuresis and diuresis and suppressed aldosterone secretion. Head-up tilt alone caused expected decreases in urine flow rate and the absolute and fractional excretion rates of sodium and increases in plasma renin activity and aldosterone levels. The combination of head-up tilt and ANP infusion resulted in a less marked decrease in urine flow rate and sodium excretion and a similar increase in plasma renin activity. However, there was a significant decrease in plasma aldosterone levels. These data support a physiologic action of ANP on renal and adrenal function.

Adult↗
PubMed1990

Peritonitis following colonoscopy in a peritoneal dialysis patient.

A 65-year-old woman on continuous ambulatory peritoneal dialysis (CAPD) developed blood-tinged dialysate and bacterial peritonitis following a colonoscopic polypectomy. She grew multiple anaerobic organisms in her dialysate despite antibiotic prophylaxis with vancomycin and gentamicin prior to the procedure. This case confirms the need for broad spectrum antibiotic prophylaxis prior to colonoscopic procedures, especially if polypectomy is planned. The antibiotic chosen should cover anaerobes as well as gram-positive and gram-negative enteric organisms. We suggest the use of ampicillin, clindamycin, and an aminoglycoside antibiotic for this prophylaxis.

Aged↗
PubMed1990

Studies on non-steroidal anti-inflammatory and related biological activities of 5-(indan-1'-yl)tetrazoles and their intermediates.

Anti-inflammatory, analgesic and anti-pyretic activities of three new 5-(Indan-1'-yl)tetrazoles and anti-inflammatory activity of corresponding carboxamides were compared to those of standard drugs, phenylbutazone and aspirin. The results indicated 5-(Indan-1'-yl)tetrazole as the most promising compound in chronic anti-inflammatory and anti-pyretic tests.

Animals↗
PubMed1982

Isolation and properties of isolated nuclei from the Florida red tide dinoflagellate Gymnodinium breve (Davis).

A simple and rapid method is described for the isolation of nuclei from the Florida red tide dinoflagellate Gymnodinium breve. The nuclei are free of cytoplasmic contamination and are active in endogenous RNA synthesis. The ratio of DNA : RNA : acid-soluble protein : acid-insoluble protein is 1:0.39:0.13:0.63, respectively, and each nucleus contains ca. 113 picograms of DNA. Electrophoretic analysis of the acid-soluble proteins reveals the presence of two histone-like proteins with molecular weights of 12,000 and 13,000.

Animals↗
PubMed1979

Dinoflagellate sterols I: Sterol c omposition of the dinoflagellates of Gonyaulax species.

The sterol composition of five species of dinoflagellates of the family Gonyaulacaeae (Div. Pyrrhophyta) were examined. All the five species (Gonyaulax acatenella, G. tamarensis, G. catennela, G. washing-tonesis, and G. polyedra) were found to contain 4 alpha-23,24(R)-trimethyl-5 alpha-cholest-22-en-3 -ol (dinosterol) and cholesterol as major sterols.

Cholesterol↗
PubMed1979

High pressure liquid chromatographic separation of two major toxic compounds from Gymnodinium breve davis.

Cultured Gymnodinium breve cells were extracted in acidified ether and fractionated by a new, convenient procedure utilizing thin layer chromatography or elution dry column chromatography. The most toxic fraction was further separated either directly by analytical high pressure liquid chromatography (HPLC) or in subsequent work by preparative, followed by analytical HPLC. Two toxic compounds, designated T46 and T47, were isolated; purity of each was demonstrated by rechromatography in analytical HPLC with both adsorptive and reverse phase packings. Both the single pass and recycle modes of operation were used with two detector systems in each to demonstrate a single entity. UV, fluorescence, and stability data differentiated these compounds from previously described, less toxic components from G. breve.

Animals↗