Articles: human.
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The exceedingly large grip forces that many older adults employ when lifting objects with a precision pinch grip (Cole, 1991) may compensate for a reduced capability to produce a stable isometric force. That is, their grip force may fluctuate enough from moment to moment to yield grip forces that approach the force at which the object would slip from grasp. We examined the within-trial variability of isometric force in old (68-85 years, n = 13) and young (n = 11) human subjects (a) when they were asked to produce a constant pinch force at three target levels (0.49, 2.25, and 10.5 N) with external support of the arm, hand, and force transducer and (b) when they were asked to grasp, lift, and hold a small test object with a precision grip. ⋯ Thumb and finger forces for grip are produced through coactivation of many muscles and thus promote smooth force output through temporal summation of twitches. We conclude that peripheral reorganization of muscle in older adults does not yield increased instability of precision grip force and therefore does not contribute directly to increased grip forces in this population. However, force instability may affect other grip configurations (e.g., lateral pinch) or manipulation involving digit abduction or adduction forces.
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Numerous experimental studies have shown that systemic or regional administration of analgesics prior to a nociceptive stimulus results in a significant reduction of analgesic requirements compared with the administration of the same analgesic dose given after the nociceptive stimulus. This phenomenon is called "preemptive analgesia". Recently several clinical studies have been conducted to determine whether "preemptive analgesia" also occurs in humans. ⋯ Most studies have failed to show a significant reduction in postoperative analgesic requirements with preemptive analgesia. Even in studies with positive results the reduction in analgesic requirements was limited and without clinical relevance. Further studies should focus on the questions which analgesics and which administration routes might provide clinically significant "preemptive analgesia" and how long analgesia should be prolonged into the postoperative period.
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Natl Toxicol Program Tech Rep Ser · Jan 1994
NTP Toxicology and Carcinogenesis Studies of o-Benzyl-p-Chlorophenol (CAS No. 120-32-1) in F344/N Rats and B6C3F1 Mice (Gavage Studies).
o-Benzyl-p-chlorophenol is an aryl halide biocide with widespread use in hospitals and households as a broad-spectrum germicide in disinfectant solutions and soap formulations for general cleaning and disinfecting. Human exposure to o-benzyl-p-chlorophenol occurs by absorption through the skin and mucous membranes and by ingestion. Toxicity and carcinogenicity studies were conducted by administering o-benzyl-p-chlorophenol (approximately 97% pure) in corn oil by gavage to male and female F344/N rats and B6C3F1 mice for 16-days, 13-weeks, and 2-years. ⋯ Other lesions considered to be associated with the nephropathy and the secondary hyperparathyroidism in male rats and in male and female mice included fibrous osteodystrophy and soft tissue mineralization. Increased incidences of squamous cell hyperplasia of the forestomach were observed in mice. Synonyms: 2-benzyl-4-chlorophenol, 4-chloro-2-benzylphenol, 4-chloro-2-(phenylmethyl)phenol, 4-chloro-alpha-phenol o-cresol, p-chloro-o-benzylphenol, 2-hydroxy-5-chlorodiphenylmethane Trade names: Bio-Clave, Chlorophene, Clorofene, Clorophene, Ketolin H, Nipacide BCPR, Preventol BPR, Santophen 1, Septiphene
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There are two main questions about the sequence of emergence of the permanent teeth in humans: 1) Why is there so much variation in sequence within human populations? (2) What is the adaptive or evolutionary significance of emergence sequence? Here, the human condition is considered by comparing us to other living primates and to our evolutionary past and considered in the light of Schultz's hypothesis that sequence of tooth emergence is adapted to rate of postnatal growth (Schultz AH. In JM Tanner (ed.) Human Growth, pp 1-20, 1960). Frequencies of individual pairwise sequences (e.g., M1 I1 vs. ⋯ Trends observed across these catarrhine primates suggest that sequence and variability in sequence can be understood by a simple model of adaptation of tooth emergence to growth rate. As rate of postnatal growth slows, molars drift to later positions in sequence, either by always emerging late in sequence, or by varying in the direction of late emergence. "Augmented sequences" (sequences written with notations about variability) are important in recognizing evolutionary trends; further, they often alter perception of similarities and differences among taxa. Although samples are small, Australopithecus africanus resembles the rapidly developing genera Macaca and Pan more than it resembles Homo sapiens. © 1994 Wiley-Liss, Inc.
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Natl Toxicol Program Tech Rep Ser · Dec 1993
NTP Toxicology and Carcinogenesis Studies of Promethazine Hydrochloride (CAS No. 58-33-3) in F344/N Rats and B6C3F1 Mice (Gavage Studies).
Promethazine hydrochloride is a drug used for the management of allergic conditions, motion sickness and nausea, and as a sedative to (treat psychiatric disorders. This drug was nominated for testing by the Food and Drug Administration because of its widespread use in human medicine and because of lack of data on its potential carcinogenicity. Oral administration is the most common route of human exposure. ⋯ The decrease in the incidences of adrenal medullary pheochromocytoma in male rats was considered to be related to promethazine hydrochloride administration. The decrease in the incidences of pituitary gland adenoma in male rats and uterine stromal polyp in female rats may have been related to promethazine administration. Synonyms: Phenothiazine,10-(2-(dimethylamino)propyl)-,monochlorohydrate; 10H-phenothiazine-10-ethanamine;10-(2-dimethylamino-2-methylethyl)phenothiazine hydrochloride; N-(2 -dimethylamino-2 -methyl)ethylphenothiazine hydrochloride Trade names: Diprazi; Kinetosin; Phenergan; Phenergan hydrochloride; Promine; Pipolfen; Plletia; Prorex; Promantine; Pyrethia; Romergan hydrochlonde