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Biomedical subjects

R M Singer

Publications and source records attributed to R M Singer.

At least 19 recordsLinked to original sources
PubMed1998

Impact of joint impairment on disability-specific domains at four years.

The objective of this study was to assess the longitudinal impact of joint impairment on overall disability and crossing domain-specific thresholds for physical activity, mobility, dexterity, instrumental activities of daily living (IADL), and activities of daily living (ADL) that are associated with use of long-term care. This 4-year longitudinal study observed 484 persons older than age 60. Logistic regression assessed the contribution of demographics, psychological mediators, lower- and upper-extremity joint impairment, and comorbidities to increased domain-specific self-reported disability above a threshold associated with use of long-term care. Lower-extremity joint impairment and age predicted crossing thresholds by year 4 in physical activity, mobility, IADL, and ADL disability that were associated with use of long-term care. Lower-extremity joint impairment is a strong risk factor for future disability that is associated with use of long-term care.

Activities of Daily Living↗
PubMed1997

Activity of Procanbid, procainamide twice-daily formulation, to suppress ventricular premature depolarizations. The Study Group Investigators.

Procainamide is a class IA antiarrhythmic drug indicated for the treatment of life-threatening or symptomatic ventricular arrhythmias. The current sustained-release formulation requires 6-hour dosing (qid). To improve patient compliance, a new sustained-release formulation for twice-daily (bid) administration has been developed (Procanbid, Parke-Davis). This study assesses the pharmacologic equivalence of the bid and qid formulations in the suppression of symptomatic ventricular premature depolarizations (VPDs). Fourteen centers enrolled a total of 99 patients with frequent symptomatic VPDs (average > or = 20 VPDs/hr) who previously responded to and tolerated the procainamide qid formulation. During the first week of the double-blind phase, patients were randomized to either placebo or procainamide dosages of 1000, 2000, or 4000 mg/d (bid or qid formulations). In the second week, the patients were crossed over to the alternate formulation. Seventy-seven patients qualified for the primary activity analysis. The bid and qid formulations showed comparable effectiveness in the suppression of mean VPDs with a linear dose-response relationship. The VPD suppression was not attenuated towards the end of the dosing interval for either formulation. Sixty-eight of these patients entered an optional 1-year extension to receive the bid formulation. Thirty-seven (54%) patients had adverse effects. Of those, 15 (22%) had side effects considered treatment related. Most of the adverse events occurred during the first 6 weeks of treatment. Only a few patients (8%) withdrew as a consequence of treatment with the bid formulation. The overall safety profile of the bid formulation was similar to other formulations, and the procainamide bid formulation has a low proarrhythmic rate (< 3%). In conclusion, the effectiveness of the twice-daily formulation of procainamide in the suppression of VPDs is comparable to the currently available qid formulation.

Aged↗
PubMed1997

Snowblower injuries to the hand.

We retrospectively reviewed the records of 62 patients who sustained serious hand injuries caused by snowblowers between 1981 and 1990. Frequency of injuries to digits tended to correlate with length (i.e., middle, index, ring, or small finger or thumb). Damage to tendons did not seem to follow any particular pattern. The majority of victims sustained multiple digital involvement. Complete versus partial amputation followed the same length distribution as did injured digits. Most of the injuries occurred to the dominant hand. When patients were further questioned regarding the circumstances and events leading to their injury, a recurring pattern was found. Most patients described a wet, heavy snow having recently fallen. The majority of the patients who were injured by placing their hands into the exit chute admitted that they were aware the machine was running, but thought that they had a greater clearance to the rotating impeller blade.

Accidents, Home↗
PubMed1990

Purpura fulminans.

Purpura fulminans is a rare disease that typically begins as a benign infectious process and subsequently progresses to severe sepsis, hypotension, purpura ecchymosis, and disseminated intravascular coagulation. We present an unusual case of an adult who was seen initially with pneumococcal sepsis that subsequently developed into purpura fulminans with major extremity involvement. A multidisciplinary approach is needed in the treatment of this often catastrophic disease.

Disseminated Intravascular Coagulation↗
PubMed1990

Transfer of the trapezius for flail shoulder after brachial plexus injury.

Shoulder arthrodesis is often used to treat flail shoulder after a brachial plexus injury, but has a high complication rate and entails loss of passive mobility. We have reviewed 27 patients with brachial plexus injury treated by transfer of the trapezius to the proximal humerus at an average time from injury of 31.3 months. Pre-operatively, all 27 shoulders were subluxated, with an average abduction of 3.5 degrees. Postoperatively, shoulder abduction averaged 45.4 degrees, and subluxation was abolished. All patients were satisfied with their improvement in function. Trapezius transfer is recommended as a simple procedure that requires only a brief period in hospital, allows early rehabilitation, and gives a satisfactory outcome, while retaining passive mobility of the shoulder.

Adolescent↗
PubMed1989

Detection of Epstein-Barr virus in CNS lymphomas by in-situ hybridization.

We used an optimized in-situ hybridization technique employing a biotinylated Epstein-Barr (EB) virus sequence, BamH1V (3.1 kb), to detect this sequence in 2 EB virus-infected cell lines (B95-8 and Namalwa) and 8 CNS lymphomas. We obtained a good hybridization signal from cytospins of B95-8 (EB virus productively infected) and Namalwa (EB virus latently infected, 1 copy per cell) cell lines. We were able to detect signal from both cell lines after overnight fixation in 10% formalin and paraffin embedding, but development time in the detection chromogen required longer incubation and the signal intensity was lower than in cytospin cells. We then used the technique to examine formalin-fixed, paraffin-embedded primary CNS lymphoma tissue from 4 patients who were immunocompromised (1 renal transplant, 3 acquired immune deficiency syndrome) and 4 patients who were not. All 4 CNS lymphomas from immunocompromised patients hybridized well with BamH1V, exhibiting a pattern of staining similar to Namalwa cells and nonlytically infected B95-8 cells. There was no relationship between the intensity and degree of reaction and the patients' survival. None of the 4 CNS lymphomas in immunocompetent patients or uninvolved brain showed any reactivity with BamH1V. We suggest that low-abundance targets are detectable in paraffin-embedded tissue by in-situ hybridization using biotinylated probes. Detection of EB viral sequences in CNS lymphomas in immunocompromised patients suggests a role for the virus in the pathogenesis of this tumor.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Skeletal traction for fractures of the femoral shaft in children. A long-term study.

Fifty-four children who had been treated with 90-90 skeletal traction for a fracture of the femoral shaft were examined after an average follow-up of 4.3 years. All of the patients were functioning normally and had a symmetrical range of motion of both hips and knees. A limb-length discrepancy of more than thirteen millimeters was found in three of thirty-nine children who were less than eleven years old and in eight of fifteen who were more than eleven years old. Traction pins that were placed obliquely were associated with a statistically significant (p less than 0.01) and predictable difference in the intercondylar angle (axis of the knee joint) as compared with pins that were placed horizontally. The study showed that pins for skeletal traction should be placed parallel to the axis of the knee joint and that fractures in children who are more than eleven years old should be reduced without overriding.

Adolescent↗
PubMed1986

CI-926 (3-[4-[4-(3-methylphenyl)-1-piperazinyl]butyl]-2,4-imidazolinedione): antihypertensive profile and pharmacology.

CI-926 (10(-7)-10(-6) M) selectively antagonized the contraction of isolated rabbit aortae to phenylephrine and displaced the alpha-1 adrenoceptor ligand WB4101 (IC50: 82 nM) in rat brain. In the spontaneously hypertensive rat, single oral doses of either CI-926 (0.3-10 mg/kg) or prazosin (0.3-100 mg/kg) caused dose-related reductions in blood pressure; however, CI-926 was more efficacious. The maximal antihypertensive response to CI-926 was unchanged with three consecutive days of oral dosing in the spontaneously hypertensive rat, whereas a first dose effect was noted with prazosin. In two-kidney, one-clip, renal hypertensive rats, CI-926 and prazosin (1-10 mg/kg) lowered blood pressure; however, prazosin was more efficacious. In perinephritic hypertensive dogs, CI-926 (10 mg/kg) lowered blood pressure 20%. In anesthetized dogs, CI-926 in the presence of supermaximal blood pressure-lowering doses of prazosin caused an additional reduction in pressure. With equivalent alpha-1 blockade in anesthetized rats, CI-926 tended to have greater hypotensive activity than prazosin. These results demonstrate that CI-926 is a potent, orally active antihypertensive agent in renin-dependent and -independent hypertension. The profile of CI-926 suggests that it lowers blood pressure in part by interacting with peripheral alpha-1 adrenoceptors and in part via an additional mechanism(s). Although weak relative to its affinity for alpha-1 adrenoceptors, CI-926 was found in preliminary experiments to interact with alpha-2 adrenoceptors, serotonergic receptors and dopaminergic receptors. The importance of these interactions to the blood pressure response of CI-926 remains to be elucidated.

Adrenergic alpha-Antagonists↗
PubMed1984

Antihypertensive effects of CI-907 (indolapril): a novel nonsulfhydryl angiotensin converting enzyme inhibitor.

CI-907 is a new orally active nonsulfhydryl angiotensin converting enzyme (ACE) inhibitor. Monoester (prodrug) and diacid forms produced concentration related ACE inhibition in guinea-pig serum (IC50 for monoester, 1.7 X 10(-7) M and for diacid, 2.6 X 10(-9) M). In isolated rabbit aortic rings and in rat and dog autonomic studies, CI-907 is highly specific in suppressing the contractile or pressor responses to angiotensin I. In two-kidney, one-clip Goldblatt hypertensive rats, single daily doses (0.03-30 mg/kg p.o.) produced dose-dependent decreases in blood pressure; 3 mg/kg lowered blood pressure to normotensive levels. In the spontaneously hypertensive rat, subacute administration of CI-907 (30 mg/kg/day for 5 days) produced the same decrease in blood pressure as that obtained in the renal hypertensive rat. In diuretic-pretreated renal hypertensive dogs, 10 mg/kg normalized blood pressure. For equivalent drops in blood pressure, heart rate increases were less in CI-907 than in enalapril-treated renal hypertensive dogs. No side effects were observed with CI-907 in any of the conscious animals. The antihypertensive response to CI-907 (0.03-1.0 mg/kg p.o.) was found to correlate with inhibition of vascular tissue ACE, but not plasma or brain ACE in two-kidney, one-clip renal hypertensive rats. These studies indicate that CI-907 is a potent antihypertensive agent with a heart rate profile different from enalapril.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1984

Antihypertensive profile of the angiotensin-converting enzyme inhibitors CI-906 and CI-907.

CI-906 and CI-907, new orally active nonsulfhydryl angiotensin-converting enzyme inhibitors, were examined for antihypertensive effects in unanesthetized hypertensive rats and dogs. In two-kidney, one-clip Goldblatt hypertensive rats, single oral daily doses (0.03-30 mg/kg) produced dose-dependent decreases in blood pressure; a single 3 mg/kg oral dose lowered blood pressure to normotensive levels. In spontaneously hypertensive rats, 30 mg/(kg X day) orally administered for 5 consecutive days achieved the same blood pressure decrease as that obtained on the first day in the renal hypertensive rats. In diuretic-pretreated renal hypertensive dogs, a 10 mg/kg oral dose decreased blood pressure by 25%. No adverse side effects were observed with CI-906 and CI-907 in any of the conscious animals. These studies indicate that CI-906 and CI-907 are potent, orally active antihypertensive agents without any apparent limiting side effects.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1983

Survey of new antihypertensive drugs: 1982.

Over 500 compounds reported to have antihypertensive activity have been cataloged from the world literature (1979-1982). The agents were classified according to mechanism: 1) drugs interacting at alpha-adrenoceptor sites; 2) beta-adrenoceptor antagonists; 3) drugs interacting with the autonomic nervous system by mechanisms other than 1 and 2; 4) inhibitors of the renin-angiotensin system; 5) diuretics; 6) vasodilator antihypertensives; and 7) drugs with miscellaneous mechanisms and/or sites of action. Within each class the drugs were subclassified and compounds that best fit the prototypes identified. The scheme is subjective, largely because of conflicting information cited in the literature. It is clear that many new drugs are at various stages of development. Whether or not these drugs will survive the scrutiny of rigorous and lengthy preclinical and clinical development, and in fact prove to be better antihypertensive agents than the currently marketed agents, remains to be established.

Antihypertensive Agents↗
PubMed1982

Induction of alkaline phosphatase activity in cultured human intracranial tumor cells.

Alkaline phosphatase activity in several cultured primary human intracranial tumor cells varied over a relatively wide range, and there was no correlation between specific activity and the type of tumor from which the cultures were derived. The enzyme was thermolabile, and its activity was strongly inhibited by l-bromotetramisole, levamisole, and L-homoarginine but not by L-phenylalanine and L-phenylalanyglycylglycine. These are the characteristics of the liver-bone-kidney form of alkaline phosphatase. Prednisolone induced increased levels of enzyme activity in most cultures, and sodium butyrate acted as an inducer in cultures of pituitary adenoma and hemangioblastoma cells. The increase was most pronounced when response cells were exposed to both stimuli simultaneously. The induced alkaline phosphatase had the same properties as the enzyme of cells grown in the absence of inducers. Increased alkaline phosphatase activity was not induced by osmolality changes of the culture medium; this feature appears to be characteristic of cells producing the liver-bone-kidney enzyme form.

Alkaline Phosphatase↗
PubMed1980

Fetal isoenzyme expression of heterotransplanted HeLa cells in nude mice.

The nude mouse has been successfully employed for the propagation of human tumors, without the need for immunosuppression. In light of the limited data on embryonic gene expression in such tumors, we undertook a study of fetal isoenzyme expression during tumor growth. HeLa TCRC-1 which has been shown to produce the placental Regan isoenzyme was used in these studies. The isoenzyme produced by these cells in culture is initially replaced by an isoenzyme referred to as chorionic. In the later stages of tumor growth, the so-called oncoamniotic (FL) isoenzyme then becomes the dominant enzyme form. The chorionic isoenzyme is produced by the early chorionic membranes of the developing conceptus, while the oncoamniotic (FL) isoenzyme is most similar to that found in the fetal human intestine. The alteration in the expression of fetal isoenzymes in tumors growing in the nude mouse is similar to that seen in the immunosuppressed rat and hamster host animals, indicating that the phenomenon is not related to immunosuppression per se.

Alkaline Phosphatase↗
PubMed1980

Convergence of isoenzyme expression in human tumor xenografts.

We have grown 7 bona fide non-HeLa contaminated cell lines in the cheek pouch of immunosuppressed adult hamsters. Six of the cell lines studied produced or continued to express the chorionic form of alkaline phosphatase under these conditions. The Regan isoenzyme produced in culture by the J82, T24, HCT-8, and COLO 16 cell lines disappeared in vivo with a concomitant appearance of the chorionic isoenzyme. The other cell lines, however, maintained the expression of the Regan isoenzyme when grown as a xenograft: the C41 line produced the Regan isoenzyme in culture, and continued to do so in vivo, while the BeWo cells, which synthesized the chorionic enzyme in culture were induced by in vivo growth to produce both the Regan and chorionic isoenzymes. No expression of the oncoamniotic (FL) isoenzyme was observed in any of the lines studied. Our results indicate a convergence of human tumor xenografts with respect to the production of the chorionic form of alkaline phosphatase. Furthermore, the loss of production of the Regan isoenzyme was seen in most, but not all cell lines studied. Since the oncoamniotic (FL) isoenzyme was only observed by HeLa cells growing as a xenograft, the expression of this enzyme form may be a HeLa specific phenomenon. We must now look to the regulation of the chorionic isoenzyme as the most promising avenue of approach to understanding the biological significance of altered isoenzyme expression in human tumor xenografts.

Alkaline Phosphatase↗
PubMed1979

Expression of KB cell alkaline phosphatase isoenzymes during growth in immunosuppressed LEW rats.

Alkaline phosphatase isoenzyme expression of human tumor xenografts was studied by the growing of KB cells in immunosuppressed neonatal LEW rats. In culture these cells produced the oncoamniotic (FL) isoenzyme as the major form and the Regan isoenzyme as a minor fraction as well as a "hybrid" that shared properties of both of the other isoenzymes. Despite a reduction in specific activity, this isoenzyme pattern was essentially unchanged during in vivo growth. KB cells "pretreated" in culture with the glucocorticoid prednisolone in hyperosmolal medium exhibited a decrease in the levels of the oncoamniotic (FL) isoenzyme and an increase in the Regan isoenzyme. During growth of pretreated cells in vivo, a time-dependent resumption in the expression of the oncoamniotic (FL) isoenzyme was associated with the disappearance of the Regan isoenzyme. This shows that the expression of the oncoamniotic (FL) isoenzyme is not restricted to human tumor cells monophenotypic with respect to alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1978

Multiple effects of glucocorticoids and hyperosmolality on isoenzyme expression in cultured KB cells.

The KB cell line, though indicted as a HeLa-contamined line, is a useful in vitro model for the study of the regulation of isoenzyme expression. KB cells produced three isoenzymic forms of alkaline phosphatase. When KB cells were grown in the presence of prednisolone and/or in hyperosmolar medium, the total enzyme activity was reduced. This change in activity was coupled with specific alterations in the proportion of each isoenzyme. The slow-moving form (identified biochemically and immunologically as the heat-stable, placental, Regan isoenzyme) was substantially increased by the steroid hormone and/or hyperosmolality. The fast-moving form [identified as the intestine-like, amnion (FL) isoenzyme] was strikingly diminished by either treatment. The intermediate form (tentatively referred to as "hybrid," inasmuch as it shared properties of the other two isoenzymes) was decreased only when KB cells were grown in hyperosmolar medium containing prednisolone. These results corroborated the notion that these stimuli cause the induction of increased levels of the heat-stable Regan alkaline phosphatase only. They also point out the necessity of performing isoenzyme analysis when one is investigating the regulation of this enzyme.

Alkaline Phosphatase↗