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Biomedical subjects

D Gross

Publications and source records attributed to D Gross.

At least 145 records · Page 8Linked to original sources
PubMed1984

Interim results on the clinical effects of i.v. administered thymopentin in active rheumatoid arthritis.

Forty-one patients with active rheumatoid arthritis entered a controlled, double-blind, randomized study; 21 received prolonged i.v. injections (10 min) of thymopentin 50 mg 3 times a week for 3 consecutive weeks; the other 20 received placebo under the same conditions. The groups were comparable at the start of the study. Statistical tests of changes within the treatment groups after 3 weeks showed that the improvement achieved in the thymopentin group was significant (p less than 0.05 or p less than 0.01) for each clinical parameter, except for left-hand grip strength. On the other hand, no significant improvement was observed for any parameter except morning stiffness in the patients on placebo. The intergroup comparison showed significant differences, favouring thymopentin over placebo treatment, in the Ritchie index, scores for swollen joints, assessment of severity of pain and scores for changes in the activity of the disease. Only minor side-effects were experienced in the two treatment groups. The present placebo-controlled double-blind study confirms the previous positive results achieved in open studies, i.e., the beneficial therapeutic effect of prolonged i.v. injections of thymopentin in patients with severe rheumatoid arthritis observed after 3 weeks of therapy. The drug appears to be safe at the dose regimen used.

Arthritis, Rheumatoid↗
PubMed1984

[Contralateral local anesthesia in stump, phantom and post-traumatic pain].

Contralateral local anaesthesia was employed in patients with chronic (n = 42) and acute (n = 8) pain syndromes (see Table 1). I. Phantom limb and stump pain: n = 10; II. Pain of face and ear: n = 10; III. Pain of neck and trunk: n = 14; IV. Pain of the hip joint: n = 6; V. Pain of the extremities: n = 10: Sa. = 50 patients. Among these were n acute pain syndromes: I.: n = 0; II.: n = 1; III.: n = 1; IV.: n = 1; V.: n = 5 (Sa.: n = 8). 42 patients with chronic pain syndromes were treated with contralateral local anaesthesia (CLA). In 27 patients CLA displayed a clear effect upon the chronic pain; in 8 patients pain release was more than 50%, in 15 patients pain release was less than 50%. 3 patients relapsed into their former condition of pain. CLA was without any positive influence in 12 cases. The medium frequency of treatments was between 5 and 6 in both groups. The average time of treatment amounted to 6 and 7 months respectively. In 8 patients with acute pain syndromes contralateral local anaesthesia produced the following results: 6 patients were permanently released from their pain; in 2 patients CLA remained without any success. The average frequency of treatment was 1.25; the average time of observation was 2.3 months. Hence we suggest that CLA should be employed as early as possible in acute or chronic posttraumatic or postoperative pain syndromes. The influence of contralateral pain therapy on acute and chronic pain conditions of the opposite side can be affirmed; its mechanism remains to be clarified. Obviously it is possible to exert an inhibitory influence from the contralateral side upon peripheral, spinal, reticular and thalamic regions, which can lead to the extinction of acute and chronic pain conditions on the opposite side. According to our experiences it is necessary that the cerebro-spinal nerve system - apart from the traumatic lesion - is intact and that the pain syndrome is not maintained by a psychic disturbance.

Acute Disease↗
PubMed1983

Theory of electromechanical effects in nerve.

The electromechanical transduction mechanisms operating in nerve membranes are considered theoretically. For mechanical-to-electrical transduction (mechanical generator potentials), a model is proposed in which the surface charge on the membrane mediates stress-induced changes in the intramembrane electric field, thus opening transmembrane ion conductance channels or reducing the ion selectivity of the membrane via leak conductance pathways. For electrical-to-mechanical transduction (axon diameter change with excitation), an investigation into two well-known electrostatic properties of dielectrics, electrostriction and piezoelectricity, in the context of the nerve membrane is undertaken which predicts a few percent change in axon dimensions for voltage- and space-clamped axons.

Axons↗
PubMed1983

Aspects of stochastic modeling for structural firesafety.

A brief review is presented of methods for stochastic modeling of fires of sufficient severity to threaten the structural safety of buildings. Information is provided on the rate of fire occurrences according to the floor area at risk for the major occupancy types.

Fires↗
PubMed1983

Antihypertensive beta-adrenergic blocking agents: N-aralkyl analogues of 2-[3-(tert-butylamino)-2-hydroxypropoxy]-3-cyanopyridine.

An interest in dual-acting antihypertensive agents, specifically those related to (S)-2-[3-(tert-butylamino)-2-hydroxypropoxy]-3-cyanopyridine (1), led us to probe the contribution of the side-chain amino substituent in this series. The ability of 1 and its various analogues to displace radiolabeled alpha 1 (WB-4101 and prazosin) and beta (dihydroalprenolol) adrenergic receptor ligands was assessed by receptor-binding techniques. Most of the compounds exhibited high beta-adrenoceptor binding affinities, but only the N-aralkylamino-substituted compounds showed high alpha 1-adrenoceptor affinities. Therefore, the vasodilation shown by 1 was not due to an interaction with the alpha 1 adrenoceptor. The aralkylamino analogues of 1 in spontaneously hypertensive rats and anesthetized dogs exhibited antihypertensive activity and alpha 1-adrenoceptor blocking properties. Unlike the preference shown by beta-adrenoceptors for S enantiomers in this oxymethylene class of beta blockers, the chirality at the secondary hydroxy center made only a minor contribution to the affinity for the alpha 1-adrenoceptor and even less of a contribution to the observed antihypertensive effects. This lack of chiral influence at the hydroxy center confirmed what had been previously observed in more limited studies with the isomers of both labetalol and medroxalol.

Adrenergic beta-Antagonists↗
PubMed1983

Ventilation by high-frequency chest wall compression in dogs with normal lungs.

In 6 anesthetized and paralyzed supine dogs, ventilation by high-frequency chest wall compression (HFCWC) was accomplished by a piston pump rapidly oscillating the pressure in a modified double blood pressure cuff wrapped around the lower thorax. Testing applied frequencies at 3, 5, 8, and 11 Hz, applied peak cuff pressures ranged from 30 to 230 cmH2O. This produced swings of esophageal pressure as high as 18 cmH2O and peak oscillatory air flow ranging from 0.7 to 1.6 L/s. Oscillatory tidal volume declined with increasing frequency and ranged from a mean of 61 to 45 ml. After 30 min of applied HFCWC, arterial blood gas determinations revealed a mean PaCO2 of 29.3 mmHg at 5 Hz, 35 mmHg at 3 Hz, 36 mmHg at 8 Hz, and 51 mmHg at 11 Hz. Mean PaO2 improved from ventilator control values at 3 Hz, remained unchanged at 5 and 8 Hz, and declined at 11 Hz. In 2 dogs breathing spontaneously, HFCWC applied at 5 and 11 Hz resulted in a reduction in spontaneous minute ventilation, mainly by a reduction in spontaneous tidal volume, whereas arterial blood gas values changed slightly. One dog ceased to breath spontaneously within 5 min of application of HFCWC as the PaCO2 fell below control values. We conclude that in dogs with normal lungs, HFCWC may assist spontaneous ventilation. In paralyzed dogs, HFCWC may be of sufficient magnitude to cause hyperventilation.

Animals↗
PubMed1983

Enhanced tracheal mucus clearance with high frequency chest wall compression.

The clearance of mucus in the trachea during high frequency chest wall compression (HFCWC) was studied in nine anesthetized dogs. High frequency chest wall compression was applied by oscillating the pressure in a thoracic cuff such that it produced oscillatory tidal volumes of 25 to 100 cc at frequencies of 3 to 17 Hz. The tracheal mucus clearance rate (TMCR) was determined by direct observation of the rate of displacement of a charcoal particle spot by means of a fiberoptic bronchoscope. Baseline TMCR during spontaneous breathing averaged 8.2 +/- 5.6 mm/min in the 9 dogs. The TMCR during 2 min of HFCWC was increased at 5, 8, 11, 13, 15, and 17 Hz but not at 3 Hz. The enhancement of clearance was most pronounced in the range of 11 to 15 Hz, reaching a peak value of 340% of control at 13 Hz. These studies suggest that HFCWC might be of considerable potential benefit as a mode of chest physiotherapy.

Animals↗
PubMed1982

[Physical therapy and rheumatism of soft tissues].

Soft tissue rheumatism (extraarticular rheumatism) is a group of common disorders found separately as independent disorders or as a symptom of systemic joint or spine diseases. The most frequent soft tissue rheumatisms are tendinopathies, rheumatism of muscles with myofascial pains, fibrositis of subcutaneous tissue and, finally, bursitis and inflammations of tendon sheaths. The commonest therapeutic procedures are non-steroidal anatirheumatic drugs, local infiltrations of corticosteroids, and physiotherapy. In the acute stages cold packs are the best physical measure against subjective pain. In subacute and chronic cases the pain in subcutaneous tissues can be lessened by connective tissue massage and underwater jet massage, muscle pain by heat and active exercises, and tendinopathies by ultrasonics and electrotherapy but very seldom by heat. In chronic bursitis and tendovaginitis, iontophoresis with potassium iodine may be helpful. Reflex pains in muscles are due to lesions of the spine and should therefore be treated by spine extension and manipulations. Every pain in soft tissue has one source in the anatomic lesion of the tissue and the second in psychogenic disorders. The latter must be sought when soft tissue pains are found all over the body on the lines of a generalized fibrositis syndrome.

Adrenal Cortex Hormones↗
PubMed1982

Streaming potential and the electromechanical response of physiologically-moist bone.

Two competing mechanisms--piezoelectricity and the streaming potential--have been proposed for the origin of electrical signals produced by the bending of physiologically-moist bone. We focus here on the streaming potential and present new experimental data in an attempt to identify the dominant mechanism. We note, however, that a clear choice cannot be made solely from qualitative observations of the bending of wet bone specimens, as both mechanisms depend in the same way on the gradient of the strain from the compression to tension faces of the specimen, where the electrodes are located, and both mechanisms produce a current proportional to the strain rate. The relation between this current and the measured voltage is shown to be influenced by specimen mechanical relaxation, which has a much longer time constant than the RC decay of the equivalent circuit. To develop more information on the streaming potential in bone, direct measurements were performed: eletrolytes of various ionic concentrations and viscosities were forced through a flat disc of bone and the potential difference across the specimen measured for corresponding fluid pressure differences. Bending tests for bone specimens soaked in the same solution used in the direct streaming potential study suggest that streaming potentials dominate piezoelectricity in wet bone bending.

Animals↗
PubMed1982

Changes in the serum of mice infected with Streptococcus pneumoniae that stimulate in-vitro multiplication of virulent but not avirulent strains.

During pneumococcal infection of mice, nucleic-acid products, including deoxynucleotides, may be released into the serum from cellular disintegration in at least three organs, the lungs, spleen and liver. The serum, after sterilisation to remove contaminating pneumococci, stimulated multiplication of virulent but not avirulent pneumococci in vitro. It also stimulated growth of virulent pneumococci in serum from uninfected animals and could be replaced, at least in part, by certain nucleic-acid degradation products at concentrations found in infected serum. The effects of the serum were lost after dialysis or dilution.

Animals↗
PubMed1982

Renal imaging with dual energy projection radiography.

Applications of dual energy radiography to renal imaging were evaluated using an experimental system for line-scanned projection radiography. This system combines digital radiographs simultaneously obtained at two differing x-ray energies (85 and 135 kVp) to create images in which materials of a desired mean atomic number are selectively cancelled. A preliminary evaluation of the technique was performed for three renal imaging problems: detection and characterization of renal masses of low radiographic contrast, evaluation of renal artery stenosis and unilateral renal ischemia, and detection of renal calculi. In all three applications, the dual energy technique produced results indicating potential advantages over conventional radiographic studies.

Adenocarcinoma↗