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Biomedical subjects

R S Goldstein

Publications and source records attributed to R S Goldstein.

142 records · Page 8Linked to original sources
PubMed1981

Transcutaneous carbon dioxide monitoring.

We studied changes in transcutaneous PCO2 in healthy volunteers and patients to establish the accuracy and practicability of a new cutaneous capnometer (HP47201A). In 9 healthy volunteers, as many as 4 experiments each were performed during each laboratory session. After cutaneous electrode stabilization, a gas mixture of CO2 in O2 was rebreathed under "open-loop" conditions allowing a rapid progressive increase in alveolar PCO2. The electrode stabilized on the skin with a time constant of 2.87 +/- 0.72 min. During rebreathing, alveolar PCO2 increased 4.25 +/- 0.63mm Hg/min. The simultaneous rate of increase in transcutaneous PCO2 was 2.91 +/- 0.59 mm Hg of CO2/min. Electrode response was also studied during steady-state conditions after a step increase in alveolar PCO2 of 10 mm Hg more than the resting end-tidal PCO2. The time constant of the skin electrode's response under these conditions was 3.2 +/- 1.9 min. We compared the arterial PCO2 of 25 blood samples with simultaneous transcutaneous PCO2 measurements in hemodynamically and metabolically stable patients. The range of arterial PCO2 values varied between 24 and 98 mm Hg, and the electrode remained stable during each 12-h study. Observed values closely approximated arterial PCO2 measurements, with transcutaneous readings 4 mm Hg more than measured arterial values (r = 0.98). We conclude that the cutaneous capnometer accurately and consistently reflects arterial PCO2 and has delay and response characteristics that may allow its use in clinical monitoring of patients.

Adult↗
PubMed1979

The effects of maternal protein deprivation on renal development and function in neonatal rats.

This study was undertaken to investigate the effects of pre- and/or postnatal maternal protein deprivation (PD) on renal functional development in the offspring. Pregnant rats were fed either a control (24% protein) or low (8 or 10%) protein diet during gestation and lactation. Progeny of these dams were cross-fostered at birth, yielding four experimental groups: pups born of control dams and nursed by PD or control dams and pups born of PD dams and nursed by control or PD dams. While the effects of prenatal PD on body and kidney growth were negligible, PD during the nursing period appeared to have a more profound effect on body and kidney weight. Renal transport functions, quantified in vitro, were differentially affected by these dietary manipulations. Renal transport capacity for organic acids and bases was depressed in pups nursed by PD dams. Maturation of the renal organic acid transport system was also delayed in these pups. alpha-Aminoisobutyric acid accumulation by renal cortical slices was enhanced only in 10-day old rats stressed by pre- and postnatal maternal PD. Renal gluconeogenic and ammoniagenic capacity was not impaired by these dietary manipulations. No differences in protein or water content of renal cortical slices were observed.

Aminoisobutyric Acids↗
PubMed1979

Absence of effects of hypoxia on small airway function in humans.

We measured the effects of sustained isocapnic hypoxia (PAO2 = 40--50 Torr; PACO2 = 38--42 Torr) on tests sensitive to small airway function in healthy human subjects. Maximum expiratory flow-volume curves on air, nitrogen-hypoxic, helium-normoxic, and helium-hypoxic mixtures as well as closing volumes while subjects breathed air and a hypoxic mixture were obtained. We then measured total lung capacity (TLC), both plethysmographically and by inert gas dilution, and used the nonplethysmographic method to measure the effects of hypoxia on TLC. In none of these tests were there any statistically significant changes when values obtained during hypoxia were compared with those during normoxia. It is suggested that previous reports that indicated that TLC was increased by hypoxia might have arisen from a plethysmographic artifact.

Adult↗
PubMed1978

Finders, keepers?: an analysis and validation of a free-found-ad policy.

A SURVEY OF LOST AND FOUND CLASSIFIED SECTIONS IN METROPOLITAN AND SMALLER NEWSPAPERS REVEALED DISPARATE RATES BETWEEN LOST ADS AND FOUND ADS: Lost ads greatly outnumbered Found ads, probably because newspapers usually require the finders of lost personal property to pay for Found advertisements. The effect of a Free-Found-Ad policy on the rate of Found advertisements placed in the Lost and Found sections of three community newspapers was investigated using a multiple-baseline design. The results suggested that the Free-Found-Ad policy was effective in increasing the rates of Found ads in all three newspapers. To determine whether increases in Found ads resulted in increases in recovered property, a sample of individuals who placed Found ads were surveyed in both baseline and treatment conditions and asked if the found items had been claimed by their owners. The Free-Found-Ad policy appeared to be effective in increasing the amount of personal property returned. The study concluded that community newspapers can provide incentives to increase such help-giving or altruistic behaviors. The implications of this study for a general policy-research strategy are discussed.

Journal Article↗
PubMed1978

Severe asthma: prevention is better than cure.

Asthmatic patients during sympton-free periods almost invariably have abnormalities in lung mechanics and gas exchange. Tentacious secretions and mucosal thickening exaggerate maldistribution of ventilation and cause flow limitation in small airways. Hence, the maximal expiratory flow volume loop in these patients will show impaired flow rates at low lung volumes and many will show a widened alveolar-arterial O2 tension difference. Preventive treatment should be aimed at reversing these abnormalities. The regular use of inhaled sympathomimetics and oral theophylline preparations is justified in the symptom-free patient whose history suggests that he is susceptible to acute exacerbations. Such patients commonly experience an improved sense of well-being, increased exercise tolerance, and a decrease in the frequency and severity of their acute episodes.

Adrenal Cortex Hormones↗
PubMed1978

Renal tubular transport of saccharin.

These experiments were designed to examine the mechanisms involved in the renal excretion of the non-nutritive sweetener, saccharin. Renal transport of saccharin in female rats was quantitatively evaluated using renal cortical slices in vitro and renal clearances in vivo. Renal cortical slices actively accumulated saccharin. Accumulation was oxygen dependent, saturable and reduced in the presence of metabolic inhibitors (2,4-dinitrophenol and sodium azide) and other organic anions 1p-aminohippurate (PAH) and probenecid]. Furthermore, addition of acetate or lactate to the medium stimulated saccharin uptake whereas reducing potassium concentration in the medium significantly decreased saccharin accumulation. Addition of saccharin to medium containing PAH and N-methylnicotinamide produced a dose-related depression of PAH accumulation. Although N-methylnicotinamide accumulation also was reduced, the depression was not dose-related. The saccharin/inulin clearance ratio of 3.76 indicates that saccharin, like PAH, undergoes tubular secretion. These findings suggest that the primary route of renal elimination of saccharin is active tubular secretion. It is also suggested that saccharin and PAH may share a common transport system.

Animals↗
PubMedDate not supplied

Predictors of functioning of patients with chronic obstructive pulmonary disease.

OBJECTIVE: To determine the extent to which mood, symptoms, lung function, and social support of patients with chronic obstructive pulmonary disease (COPD) predicted their level of functioning over a 30-month period. DESIGN: Prospective, longitudinal. SETTING: The homes of patients living in or adjacent to metropolitan Toronto. SUBJECTS: Seventy-one patients (48 men and 23 women) with COPD who had a forced expiratory volume in 1 second less than 50% of predicted (FEV1 < 50%) and who spoke English. They ranged in age from 43 to 81 years (mean 66.37 years). OUTCOME MEASURES: The patients' level of functioning at the final data collection visit, 30 months after the initial measure. INSTRUMENTS: At both data collection visits patients completed measures of mood (negative mood scales of the Profile of Mood States), symptoms (Bronchitis-Emphysema Symptom Checklist), social support (Personal Resource Questionnaire), and functioning (Sickness Impact Profile). RESULTS: Data were analyzed by use of multiple regression analysis. From measures taken at the initial visit (T1), the best predictors of patients' functioning at 30 months (T2) were their functioning at T1, symptoms, FEV1, and age. Together these accounted for 70% of the variance in the final functioning scores, with initial functioning scores accounting for 51% of the variance. The most prevalent symptoms were dyspnea and fatigue, and both were highly correlated with functioning scores 30 months later. CONCLUSIONS: In this study, symptoms, FEV1, and age are predictive of functioning in patients with COPD over a 30-month time frame. However, only 50% of the 143 patients recruited into the study completed it. Therefore caution needs to be exercised when the results are applied to other patients with COPD.

Activities of Daily Living↗
PubMedDate not supplied

Multidrug-resistant tuberculosis: long term follow-up of 40 non-HIV-infected patients.

BACKGROUND: There has been a steady increase in referrals of patients with multidrug-resistant tuberculosis (MDR-TB) who are human immunodeficiency virus (HIV) negative. Between 1986 and 1999, 40 patients were admitted to the authors' institution, eight of whom were admitted between January and June 1999. The management of such individuals is difficult. Although they are a clinically and epidemiologically important group of patients, few reports detail their management. OBJECTIVES: To review the demographics, clinical management and long term outcome of 40 non-HIV-infected individuals with MDR-TB referred to the only specialized TB inpatient service in Ontario. PATIENTS AND METHODS: Clinical hospital records were reviewed. RESULTS: Twenty-one men and 19 women (mean age 41+/-18 years) were admitted between January 1986 and June 1999 with MDR-TB and negative serology for HIV. Thirty-eight patients (95%) were born outside of Canada. Twenty-six patients (65%) had a history of previous TB. All were symptomatic with productive cough and positive sputum smears for acid-fast bacilli. There was a delay of 4.5 months between the initial diagnosis of TB and the recognition of the presence of MDR-TB. Four patients (10%) had TB resistant to isoniazid and rifampin only. Over 50% of patients had TB with additional resistance to streptomycin, and over 40% had additional resistance to ethambutol. Coexisting resistance was also found in significant numbers for pyrazinamide, ethionamide, para-aminosalicylic acid and cycloserine. Bacteriological conversion was achieved in 34 patients (85%). Six patients underwent surgical resection for localized lung disease. Twenty-four patients completed treatment and have remained free of disease for 33+/-25 months. All five patients (12%) who died had longstanding disease before their referral. CONCLUSIONS: MDR-TB is most frequently seen among immigrants with a previous history of TB, especially if they come from countries in which TB is highly prevalent. Outcome can be improved by a more timely recognition of MDR-TB.

Adult↗
PubMedDate not supplied

Pulmonary rehabilitation programs in Canada: national survey.

OBJECTIVE: To characterize pulmonary rehabilitation (PR) programs in terms of their type, size, duration, patient population, content and staffing. DESIGN: Surveys were sent to members of the Rehabilitation Committee of the Canadian Thoracic Society, as well as any program identified by members of the Canadian Physiotherapy Cardio-Respiratory Society, by provincial lung associations or by the respondents. PARTICIPANTS: Of 51 surveys sent, responses were received from 44 facilities (86% response rate). In-patient or out-patient pulmonary rehabilitation programs were offered by 36 facilities. RESULTS: Most programs (97%) admitted out-patients, and 22% had an in-patient capability. Out-patient programs enrolled 13 patients (median 11; range five to 48) at a given time for a duration of 8.3 weeks (range two to 26). In-patient programs enrolled nine patients at a given time (range two to 26) for 4.6 weeks (range one to eight). Programs included patients with chronic obstructive pulmonary disorder (100%), restrictive disease (93%), asthma (82%), adults with cystic fibrosis (46%), patients pre- or postlung transplantation (45%) and patients receiving mechanical ventilatory support (18%). Breathing retraining, education and upper extremity training were incorporated in more than 90% of all programs. Only one-third of programs offered smoking cessation as part of the rehabilitation. Education sessions on medications and inhaler usage were included in most programs, but sexuality was addressed in only half the programs. CONCLUSIONS: This first comprehensive national survey of PR programs in Canada shows that there are similarities in the format, content and staffing of PR programs. Programs are only able to service a small percentage of patients with chronic respiratory conditions.

Adult↗
PubMedDate not supplied

Role of pharmacokinetics and metabolism in the enhanced susceptibility of middle-aged male Sprague-Dawley rats to acetaminophen nephrotoxicity.

Middle-aged male Sprague-Dawley (SD) rats (9-12 months) are more susceptible to acetaminophen (APAP)-induced nephrotoxicity than are young (2-3 months) adult males. The present studies were designed to evaluate the role of pharmacokinetics and renal and hepatic metabolism of APAP in age-dependent nephrotoxicity. Following 750 mg/kg APAP, ip, a nephrotoxic dosage in 12-month-old but not 3-month-old rats, renal cortical APAP concentrations were significantly greater in 12-month-old compared with 3-month-old SD rats at 3, 4, and 6 hr after treatment. Renal medullary APAP concentrations in 12 month-old rats were significantly greater than in 3-month-old rats at 2, 3, and 5 hr after treatment. Serum APAP concentrations were significantly elevated in 12-month-old compared with 3-month-old rats from 2 through 5 hr after APAP (750 mg/kg ip). However, APAP tissue/serum concentration ratios were similar in 3- and 12-month-old rats, indicating that differences in tissue concentration were secondary to increased serum concentrations in older rats. Conjugated APAP metabolites in blood were similar in 3- and 12-month-olds during the initial 2-3 hr after 750 mg/kg APAP, ip, but began to accumulate in 12-month-old but not 3-month-old rats within 6-8 hr after APAP administration, perhaps secondary to declining renal function. After 500 mg/kg APAP, iv, blood APAP concentrations were markedly elevated in 12-month-old compared with 3-month-old rats during the entire course of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaminophen↗