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Biomedical subjects

R Block

Publications and source records attributed to R Block.

At least 37 records · Page 2Linked to original sources
PubMed1987

Water content in human intervertebral discs. Part I. Measurement by magnetic resonance imaging.

Tension-relaxation experiments were performed on human disc lamellae specimens. The water content was found to affect the viscoelastic behavior and a master relaxation curve was constructed from the experimental data. The water content of disc phantoms is measured by magnetic resonance imaging (MRI) techniques. MRI was used to compare the discs of patients of different ages. The possibility of obtaining cross-sectional water distribution in human intervertebral disc material using MRI techniques and its relation to the disc's mechanical properties was explored, with the goal of constructing a realistic mathematical model of the disc which takes into account the water content of the disc.

Body Water↗
PubMed1987

Increased in vitro histamine responses in human small airways smooth muscle from patients with chronic obstructive pulmonary disease.

We tested the hypothesis that abnormal responses of airway smooth muscle contribute to the pathogenesis of airway obstruction in chronic obstructive pulmonary disease (COPD). For this purpose, lung tissue from 10 patients with and 10 patients without COPD was obtained during thoracotomies. Lung function was measured preoperatively. The in vitro responses of isolated bronchioles were measured using histamine, leukotriene (LT)C4, and methacholine as contracting agents, and the results of the in vitro measurements were compared between patients with and without COPD. Histamine efficacy (maximal isometric force, Tmax) in vitro of bronchioles from patients with COPD was significantly greater than the histamine Tmax of the bronchioles from patients without COPD (p less than 0.01). This difference was probably not due to histamine tachyphylaxis or the production of relaxing prostaglandins by airways without COPD, as neither mechanism could be detected in separate experiments on airways without COPD. No differences were found between in vitro bronchiolar responses to LTC4 and methacholine in patients with and patients without COPD. Increased histamine responses of small airways may be one of the determinants of airway obstruction in COPD.

Bronchi↗
PubMed1987

Changing patterns of health insurance coverage: special concerns for women.

Health care expenditures and utilization have increased dramatically in recent years, but gaps in health insurance coverage restrict access to care for a growing portion of the population. Women are especially vulnerable given the structure of insurance coverage and demographic factors. The erosion of insurance coverage can be attributed to several trends, particularly employer cost containment strategies, restricted public program eligibility and changes in the characteristics of the work force. Numerous measures have been adopted at the federal and state levels to maintain or expand coverage on an incremental basis. As broader segments of the population suffer reduction or loss of coverage, a comprehensive approach will be necessary to ensure universal access to health care.

Adolescent↗
PubMed1986

Resistance and nonfatal outcomes in stranger-to-stranger predatory crime.

This article examines the consequences of encounters between strangers that might have resulted in robbery or rape and explores how the eventual outcomes of those incidents were related to the resistance offered by their potential victims. It is based on data from the National Crime Survey. Although the conclusions necessarily are tentative, it appears that forceful resistance was related to less frequent success by robbers, but robbery victims resisting forcefully had a greater risk of being physically attacked. Forceful resistance in potential rape incidents was related to higher risk of attack and bodily injury with no apparent reduction in risk of rape. On the other hand, victims who were able to offer nonforceful resistance reported a reduced risk of being robbed and suffered less frequent attack and injury. In rape incidents, nonforceful resistance was linked to lower risk of actual rape but was unrelated to risk of attack or other forms of injury.

Cross-Sectional Studies↗
PubMed1985

Increased sensitivity of the elderly to the central depressant effects of diazepam.

The effects of diazepam on memory and psychomotor performance in healthy elderly (N = 12) and young (N = 12) individuals were examined. Diazepam was administered acutely in a single, oral 2.5 mg dose. Diazepam impaired memory, both immediate and delayed recall, and psychomotor performance in the elderly subjects. In addition, the drug caused an increase in self-reported sedation in elderly subjects but not in young subjects. These findings suggest an age-related increase in the sensitivity of elderly individuals to the central depressant effects of diazepam.

Administration, Oral↗
PubMed1984

Adverse effects of single therapeutic doses of diazepam on performance in normal geriatric subjects: relationship to plasma concentrations.

Elderly normal volunteers (N = 12, mean age 70.4 years) were administered placebo or diazepam 2.5, 5, 10 mg in four consecutive sessions separated by at least a 1-week interval. Memory and psychomotor performance and plasma diazepam concentrations were assessed at baseline and at 1 and 3 h following drug administration. Significant impairments were found in response to all doses of diazepam. The maximum impairment occurred at 1 h, which coincided with the highest plasma concentration of the drug.

Aged↗
PubMed1984

Lithium-induced increases in red blood cell choline and memory performance in Alzheimer-type dementia.

To investigate the relationship between RBC choline and memory in Alzheimer-type senile dementia (SDAT), lithium carbonate was administered to 14 SDAT patients in doses of 400-600 mg/day for 5 weeks. A battery of memory tests was administered at baseline and at weekly intervals. Five patients with serum concentrations below 0.6 meq/liter developed neurotoxicity and were dropped from further analysis. For the remaining patients, Li+ with mean serum concentrations up to 0.6 meq/liter did not alter memory scores significantly. The dramatic increases in RBC choline during the study, however, suggest that RBC choline is not correlated with memory functioning in SDAT.

Aged↗
PubMed1983

Attenuation of pilocarpine-induced hypothermia in response to chronic administration of choline.

Chronic treatment of rats with choline caused a decrease in the hypothermic response to pilocarpine. The action of choline on the muscarinic receptors is consistent with electrophysiological and binding studies, supporting a direct muscarinic action for choline. Administration of direct muscarinic agonists has been shown to cause a decrease in the number of muscarinic receptors. Thus, the long-term use of cholinergic precursors could have some adverse effects on central cholinergic functioning.

Animals↗
PubMed1979

Unionism in the health care industry: an overview.

Block profiles the two unions that are the most active in organizing non-nurse health care employees: the National Hospital Union (NHU) and the Service Employees International Union (SEIU). The two international unions present a contrast in structure and ideology. The SEIU is a truly international, decentralized union, whereas NHU is a far more centralized affiliate. As an international union, SEIU characterizes, taxes, and disciplines locals. Its decentralized strategy has been to permit locals to do the bulk of the organizing and collective bargaining, while the national union merely coordinates and offers financial and technical support. Conversely, NHU is an affiliate of the retail, wholesale, and department store union, deriving authority from, paying tax to, and subject to discipline by the parent organization. Its centralized approach has been for national officers to determine when a district will be created and what its jurisdiction will be. The structural differences of the two unions can be traced to their respective histories. As an old-line AFL union, SEIU had an existing structure of independent local unions that operated in health care as they did in other industries. NHU, however, originated as a union of drug store employees and its structure evolved over time. Membership growth and geographic expansion elevated it beyond the status of a local into a division with its own districts. The unions also diverge in their ideology; SEIU takes a more traditional business union approach to collective bargaining and unionism, while NHU is oriented to social welfare, involving itself in more than the work aspect of members' lives. These differences again can be attributed to contrasting histories of the old-line SEIU and the more radical NHU. The authors emphasize that unions are not homogeneous entities but organizations that respond to a similar environment as a result of their respective structures and histories.

Health Workforce↗
PubMed1975

Purification and properties of stringent factor.

The stringent factor from Escherichia coli is the product of the relA locus. It is the enzyme that catalyzes the synthesis of pppGpp and ppGpp eliciting a pyrophosphate transfer from ATP to the 3'--OH of GTP (or GDP). This protein is responsible for the synthesis of pppGpp and ppGpp in stringent strains in response to an amino acid starvation. In vitro it catalyzes the synthesis of these guanosine compounds in either a ribosome-dependent reaction that requires a particular conformation of the ribosome i.e. the presence of an uncharged tRNA recognizing a codon in the acceptor (A) site of the ribosome or in a ribosome-independent reaction at temperatures under 30 degrees in the presence of only buffer, salts, and substrates. Here we report the purification of the stringent factor to near homogeneity. It is a monomeric protein with a molecular weight of 75,000. The properties of the ribosome-independent reaction are studied and it is shown that the presence of certain acidic proteins, such as the 50 S ribosomal proteins L7 and L12 or casein, or 20% methanol or both stimulates the reaction by creating an environment that together with the low temperature further stabilizes the stringent factor.

Adenosine Triphosphate↗