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Biomedical subjects

B Greenberg

Publications and source records attributed to B Greenberg.

At least 181 records · Page 10Linked to original sources
PubMed1978

Evaluation of a clinical medical librarian program at the Yale Medical Library.

A clinical medical librarian (CML) program in a large university-based teaching hospital setting is viewed by the majority of clinicians as education-oriented, with slightly fewer clinicians viewing it as patient care oriented. The CML service has been utilized for research purposes only when it is clear that case-relevant information can evolve into research intended to have "clinical" impact. This study reports the results of a questionnaire circulated among clinicians receiving CML support by a large medical school library. Results indicate that (1) the CML effected a change in information-seeking behavior by the clinicians--they obtained information that would not have been available to them if the CML had not been present in patient-management conferences; (2) relevancy of information provided by the CML was judged by the clinicians to be very high; (3) the accuracy of the CML's search, coupled with the rapidity of delivery, was found to be highly satisfactory; (4) acceptance of the CML within the patient care setting was acknowledged by the majority of clinicians, who contact the CML in-hospital and overwhelmingly prefer to do so; and (5) there was no statistically significant variation in the manner in which different medical specialties use the services of a CML. These findings justify implementation of a clinical medical librarian program, on a modified basis, as an additional service to already existing reference services offered by a large medical school library.

Connecticut↗
PubMed1977

Hemodynamic advantage of combined administration of hydralazine orally and nitrates nonparenterally in the vasodilator therapy of chronic heart failure.

Patients with severe left ventricular failure generally have both reduced cardiac output and increased pulmonary and systemic venous pressures. A study was therefore made of the use of combined vasodilator therapy with nonparenterally administered nitrates, which act primarily on venous capacitance vessels and thus reduce preload, and orally administered hydralazine, which acts on arteriolar resistance vessels and thus reduces afterload. Twelve patients with chronic refractory heart failure were given these drugs individually and in combination during continuous hemodynamic monitoring. Heart rate and arterial pressure did not change significantly. Nitrates significantly reduced filling pressures of both ventricles without affecting cardiac index. Hydralazine did not alter filling pressures but dramatically increased cardiac index. The hemodynamic effects of each drug were additive during combined therapy, resulting in a 36 percent (28 to 18 mm Hg) mean decrease in left ventricular filling pressure and a 58 percent (2.1 to 3.3 liters/min per m(2)) mean increase in cardiac index. The seven patients who have continued to receive combined therapy for 3 to 10 months have shown sustained clinical improvement.

Administration, Oral↗
PubMed1977

Effects of antibiotics on the survival of Salmonella in the American cockroach.

The faecal survival of Salmonella typhimurium orally administered to restrained American cockroaches maintained on an antibiotic diet was investigated. Significant reductions in median numbers of total aerobic faecal microorganisms were noted in insects fed antibiotics daily, and when Salmonella was introduced to this modified micro-environment, it persisted for 44 days in all specimens. Multiplication of the pathogen was also observed in these insects, with numbers often exceeding 10(3) times that of the initial input. This differs significantly from our previous results showing that the pathogen is unable to multiply in conventional cockroaches. Attempts to restore the normal flora by feeding a faecal suspension from untreated cockroaches resulted in a decrease in numbers of Salmonella excreted, but did not result in their elimination. Carcasses of infected cockroaches retained viable Salmonella for at least 60 days post mortem, or 104 days after the infective meal.

Administration, Oral↗
PubMed1977

MEDLINE demand profiles: an analysis of requests for clinical and research information.

When a medical library serves both research scientists and practicing physicians, it may be predicted from the results of previous studies that computerized bibliographic search services will show more research and less clinical activity. The present paper reports the results of a statistical analysis of professional use of the National Library of Medicine's bibliographic retrieval system. MEDLINE (Medical Literature Analysis and Retrieval System on-Line), at a large medical school library. Results indicate that (1) demand for MEDLINE service is primarily research oriented; (2) frequency of use bears a relationship to rank and departmental affiliation; (3) broad and comprehensive searches are requested more frequently than searches for specific information; (4) usage shows an interesting curvilinear relationship with age and status of the user; and (5) grant funds and support correlate with the number of searches requested. Implication of these findings are that since clinicians' use of MEDLINE was found to be minimal, information services should be reevaluated in order to assist in meeting their information needs more effectively.

Connecticut↗
PubMed1976

Timing of single daily meal influences relations among human circadian rhythms in urinary cyclic AMP and hemic glucagon, insulin and iron.

Relations among circadian rhythms in serum iron, glucagon and insulin and urinary cyclic AMP excretion differ drastically when diurnally active, nocturnally resting human adults consume all daily food for one week as breakfast only and for another week as dinner only - a finding of interest to diverse fields, e.g., for optimizing certain kinds of therapy or for a better utilization of calories.

Circadian Rhythm↗
PubMed1976

Salmonella in the American cockroach: evaluation of vector potential through dosed feeding experiments.

Restrained American cockroaches, Periplaneta americana L., were fed graded doses of Salmonella typhimurium ranging from 1-6 X 10(3) to 2-0 X 10(6), and their faeces assayed daily for the pathogen. Only 4 specimens out of 117 demonstrated multiplication of salmonellas, which was unrelated to size of input. When data of persistence regardless of actual numbers were expressed as percentage Salmonella-positive faecal-days, and these transformed to probits, a graph of percentage-positive faecal-days versus log dose allowed a calculation of the CD 50, or contaminative dose required for 50% of the faecal-days to be infective. The CD 50 for this cockroach species was 1-4 X 10(6) Salmonella.

Animals↗
PubMed1976

Oral hydralazine therapy for chronic refractory heart failure.

The hemodynamic effects of oral hydralazine were investigated in ten patients (nine in NYHA Class IV and one in Class III) with chronic refractory heart failure. With hemodynamic monitoring, adequate oral doses of hydralazine (50 or 75 mg) were determined and then administered every six hours. Hemodynamics were determined at 2-3, 6-8 and 24 hours on hydralazine therapy. Arterial pressure decreased slightly (5%) and systemic vascular resistance decreased significantly (42%). Cardiac and stroke volume index increased by 70 and 66%, respectively, without any significant change in heart rate, pulmonary capillary wedge or right atrial pressure. Hemodynamic improvement was associated with clinical improvement without a major complication. During the follow-up period of 3-7 months, seven of nine patients were in NYHA Class II and one in Class III. One other patient died suddenly six weeks after discharge. These findings suggest that hydralazine in an effective oral vasodilator for the treatment of refractory heart failure.

Adult↗
PubMed1975

A deoxyribonuclease of Diplococcus pneumoniae specific for methylated DNA.

A deoxyribonuclease specific for methylated DNA was isolated from Diplococcus pneumoniae. The enzyme, an endonuclease, degrades DNA for Escherichia coli to fragments of average molecular weight about half a million; it forms discrete fragments from phage lambda DNA. Methyl-deficient E. coli DNA is not attacked, neither is DNA from Micrococcus radiodurans, which contains no methylated adenine or cytosine. Nor is DNA from D. pneumoniae or phage T7 attacked. However, DNA from M. radiodurans, D. pneumoniae, and T7 is attacked after methylation with and E. coli extract. Methylated T7 DNA is degraded to discrete fragments. Although the genetic transforming activity of normal DNA from D. pneumoniae is not affected by the enzyme, transforming activity of methylated DNA is destroyed. The enzyme is designated endonuclease R Dpn I. Under certain conditions another enzyme of complementary specificity can be isolated. This enzyme, designated endonuclease R Dpn II, produces a similar pattern of fragments from the DNA of T7 without prior methylation of the DNA. It also degrades normal DNA for D. pneumoniae. It is suggested that this pair of enzymes plays a role in some unknown control process, which would involve a large fraction of the specific base sequences that are methylated in E. coli DNA and are present but not methylated in DNA from other sources.

Chromatography, Gel↗
PubMed1975

Identification of a deoxyribonuclease implicated in genetic transformation of Diplococcus pneumoniae.

A mutation of Diplococcus pneumoniae, end-1, reduces the major deoxyribonuclease activity of the cell, an endonuclease, to 10% of its normal value without impairing transformation. Further mutations, called noz, abolish the residual endonuclease activity and block transformation. The residual endonuclease is similar to the wild-type enzyme in size, charge, divalent cation dependence, inhibition by ribonucleic acid, and formation of oligonucleotide products. However, the mutant endonuclease is more temperature sensitive, which suggests that the end-1 mutation occurred in a structural gene for the enzyme. Genetic analysis showed that the noz mutations occur at the same genetic locus. A number of new end mutants were analyzed. Those that retained more than 1.4% of the normal endonuclease activity were essentially normal in transformation; those with less than 1% were defective. The transformation-defective end mutants appear to be blocked in the entry of deoxyribonucleic acid (DNA) since they carry out the prior step of binding DNA to the outside of the cell. The major endonuclease of the cell may act as a DNA translocase by attacking and degrading one strand of DNA, thereby facilitating entry of the complementary strand into the cell.

Cations, Divalent↗