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Biomedical subjects

P Rubin

Publications and source records attributed to P Rubin.

At least 289 records · Page 16Linked to original sources
PubMed1981

Comparison of 24-hour insulin requirements in IDDM patients during control by an artificial betacell and during conventional therapy.

Insulin requirements were measured over 24 hours during feed-back control by an artificial betacell (Biostator) in 25 lean insulin-dependent diabetics with no endogenous insulin secretion. The set of constants selected for the algorithms was that which resulted in the minimum insulin infusion consistent with normal glucose tolerance during an OGTT. The results were compared with the daily dose of insulin chosen, using standard clinical criteria, by physicians with no knowledge of the experimental results. Plasma IRI remained within the normal range during Biostator control, and the insulin dose given over 24 hours was almost identical - 101 +/- 9% with that selected on clinical grounds. The reproducibility of insulin requirements established with the Biostator was tested over two consecutive days in nine patients; all required an increased amount of insulin (mean + 6.9%, range + 0.5 to + 12.2%) on the second day.

Adolescent↗
PubMed1981

The use of modified Cunningham chambers for the enumeration of H rosettes, E rosettes, and lymphocyte-tumour cell conjugates.

In this paper, we have described the use of a slide-coverslip Cunningham chamber which is ideal for counting delicate rosettes and lymphocyte-tumour cell conjugates. The ease of construction, facility of use, and economy of cost in comparison with hemocytometers make the use of these chambers the method of choice for rosette counts in general. In contrast to standard double-slide Cunningham chambers, the design of these rosette chambers is such that they can be used with ordinary light microscope objectives (including oil immersion), they can be more easily loaded without trapping air bubbles, and they can be sealed without tilting the slide. As an example of one potential application of these chambers to tumour immunology, data have been presented showing the high proportion of lymphocyte-tumour cell conjugates which can be formed by human peripheral blood cells. The ability of any particular tumour cell to form conjugates did not necessarily reflect the susceptibility of that cell type to natural killer (NK) cell-mediated lysis, nor was there any evidence that E rosette-forming cells preferentially formed conjugate in comparison to non E rosette-forming cells.

Killer Cells, Natural↗
PubMed1981

Effect of naloxone, a specific opioid inhibitor, on blood pressure fall during sleep.

The study was designed to investigate the possible role of endogenous opioids in the fall in blood pressure (BP) seen during initial sleep. Seven normal men, ages 20-30 years, were studied for three consecutive nights. Each night, electroencephalogram, chin electromyogram, electrooculogram, heart rate (all continuously), and blood pressure (every 15 minutes) were recorded. Night 1 was used for orientation. On nights 2 and 3, subjects received, in randomized order, an infusion of naloxone 0.2 mg/kg over 1 minute or volume-matched saline. Blood pressure data from the first 4 hours of non-rapid eye movement sleep were combined. On the placebo night, systolic BP fell from 114.6 +/- 6 mm Hg to 103.7 +/- 8 mm Hg (+/- SD) (p < 0.05, Wilcoxon rank-sum test). On the naloxone night, systolic BP did not change. Neither diastolic BP nor heart rate were influenced by naloxone. these data suggest that endogenous opioids could be involved in the fall in systolic BP seen during initial sleep.

Adult↗
PubMed1981

Patterns of human interlimb coordination emerge from the properties of non-linear, limit cycle oscillatory processes: theory and data.

The present article represents an initial attempt to offer a principled solution to a fundamental problem of movement identified by Bernstein (1967), namely, how the degrees of freedom of the motor system are regulated. Conventional views of movement control focus on motor programs or closed-loop devices and have little or nothing to say on this matter. As an appropriate conceptual framework we offer Iberall and his colleagues' physical theory of homeokinetics first elaborated for movement by Kugler, Kelso, and Turvey (1980). Homeo kinetic theory characterizes biological systems as ensembles of non-linear, limit cycle oscillatory processes couple and mutually entrained at all the levels of organization. Patterns of interlimb coordination may be predicted from the properties of non-linear, limit cycle oscillators. In a set of experiments and formal demonstrations we show that cyclical, two-handed movements maintain fixed amplitude and frequency ( a stable limit cycle organization) under the following conditions: (a) when brief and constantly applied load perturbations are imposed on one hand or the other, (b) regardless of the presence or absence of fixed mechanical constraints, and (c) in the face of a range of external driving frequencies from a visual source. In addition, we observe a tight phasic relationship between the hands before and after perturbations (quantified by cross-correlation techniques), a tendency of one limb to entrain the other (mutual entrainment) and that limbs cycling at different frequencies reveal non-arbitrary, sub-harmonic relationships (small integer, subharmonic entrainment). In short, all the above patterns of interlimb coordination fall out of a non-linear oscillatory design. Discussion focuses on the compatibility of these results with past and present neurobiological work, and the theoretical insights into problems of movement offered by homeokinetic physics. Among these are, we think, the beginnings of a principled solution to the degrees of freedom problem, and the tentative claim that coordination and control are emergent consequences of dynamical interaction among non-linear, limit cycle oscillatory processes.

Journal Article↗
PubMed1980

Total (half-body) systemic irradiation for occult metastases in non-small cell lung cancer: an Eastern Cooperative Oncology Group pilot report.

There is a high probability for patients with locally advanced, unresectable, nonmetastatic, nonsmall-cell bronchogenic carcinoma (NSCBC) to harbor subclinical distant metastases at diagnosis. Approximately 30% will disseminate in the first three months and an additional 50% will disseminate before a year has elapsed. Twenty advanced nonmetastatic patients with NSCBC were treated with localized split-course chest irradiation (LCI) plus total body body (upper and lower half-body) irradiation for occult metastases. Thirty equally advanced, nonmetastatic patients, who were treated with only localized split-course chest irradiation, were matched and served as a retrospective control group. The first 11 patients received HBI after LCI (Pilot Study No. 1), but five (45%) had evidence of distant metastases before UHBI was delivered. This was not different from the control group where 11 (37%) of the patients had evidence of distant dissemination less than 2 1/2 months from the onset of treatment. The remaining nine patients received UHBI first followed by LCI and LHBI (Pilot Study No. 2); only one (11%) had evidence of distant metastases in the first 2 1/2 months. Apparently, the median recurrence free survival, metastatic free interval, and median survival were significantly prolonged, and there was a decrease in the incidence of liver metastases in patients receiving HBI for occult metastases over the patients of the control group. An increase in local tumor control was seen when large single doses of UHBI were added to LCI. Although elective HBI seems to delay the appearance of distant metastases, it did not prevent their occurrence, alter patterns of first relapse, or significantly improve the overall survival. Nevertheless, a therapeutic gain may have been achieved and is discussed. These two high-risk Phase II Pilot Studies for the Eastern Cooperative Oncology Group (ECOG) have served as the basis for a larger randomized protocol where this therapeutic strategy will be tested against other therapies. The incidence of radiation pneumonitis with 800 rad of UHBI corrected for lung transmission was 9%, or one of 11 patients. A hypothesis and rationale for a more effective combined modality therapy in these patients is given.

Carcinoma, Bronchogenic↗
PubMed1980

Studies on the clinical pharmacology of prazosin. II: The influence of indomethacin and of propranolol on the action and disposition of prazosin.

1 The possibility of pharmacodynamic and pharmacokinetic interactions of prazosin with indomethacin and with propranolol have been studied in healthy subjects. 2 In four out of nine individuals indomethacin considerably attenuated prazosin-induced hypotension, but noradrenaline concentrations were unchanged from the day when blood pressure fell greatly. The effect of prazosin in the other five subjects was not influenced by indomethacin. 3 Indomethacin prevented the rise in plasma renin activity seen following administration of prazosin alone. 4 Propranolol did not prevent the syncope associated with the first dose of prazosin. 5 Propranolol affected neither the absorption nor elimination of prazosin. 6 It is concluded that in certain subjects indomethacin can largely prevent the hypotensive effect of parazosin, possible by increasing adrenergic receptor sensitivity. The theoretical possibility that propranolol could influence prazosin disposition or syncope was not substantiated.

Adult↗