Showing papers by "University of Texas Health Science Center at Houston published in 1971"
TL;DR: Using a special staining technique, a survey of the chromosomes of many mammalian species showed that constitutive heterochromatin is present in all cases and that the heterochromaatin pattern appears to be specific and consistent or each chromosome and each taxon.
Abstract: Using a special staining technique, a survey of the chromosomes of many mammalian species showed that constitutive heterochromatin is present in all cases and that the heterochromatin pattern appears to be specific and consistent or each chromosome and each taxon. Usually heavy heterochromatin is found in the centromeric areas, but terminal heterochromatin is not uncommon. Occasionally interstitial heterochromatin bands occur. In some species, such as the Syrian hamster and Peromyscus, many chromosome arms are completely heterochromatic.
197 citations
TL;DR: Through the use of a special technique that permits visualization of heterochromatin, seven heterochromaatin variants have been found among four individuals, suggesting a very high frequency of variability of heterchromatin in the population.
Abstract: Genetic polymorphism has been demonstrated in man for many characteristics including blood groups, serum proteins, tissue enzymes, and hemoglobins. A class of chromosomal polymorphism involving constitutive heterochromatin has now been found. Through the use of a special technique that permits visualization of heterochromatin, seven heterochromatin variants have been found among four individuals. These results suggest a very high frequency of variability of heterochromatin in the population.
147 citations
Journal Article•
TL;DR: The ability of the antibiotic bleomycin to cause single- as well as double-strand breaks in deoxyribonucleic acid in vitro has been confirmed and the presence of the reducing agent is not obligatory.
Abstract: The ability of the antibiotic bleomycin to cause single- as well as double-strand breaks in deoxyribonucleic acid in vitro has been confirmed. Heat-denatured, single-stranded DNA is considerably more sensitive to the action of bleomycin than is native DNA. The rate of the reaction of DNA breakage by bleomycin is enhanced in the presence of 2-mercaptoethanol; however, 2-mercaptoethanol also inactivates bleomycin. This inactivation reaction is especially rapid at 80°, although bleomycin itself is stable to heating at 100° for 10 min. Bleomycin alone causes the fragmentation of DNA upon prolonged incubation, and therefore the presence of the reducing agent is not obligatory. In the presence of high concentrations of bleomycin, the DNA is degraded to the level of free nucleotides, nucleosides, or bases.
110 citations
TL;DR: Two experiments were designed to determine conditions under which moderate drinking could be maintained for 5 days in succession, and demonstrated that it was the absence of reinforcement contingencies for moderation, rather than living in an impoverished environment, which resulted in excessive drinking.
Abstract: Healthy chronic alcoholics were hospitalized and given access to substantial quantities of ethanol in an effort to limit their drinking by the application of contingency-management procedures. Two experiments were designed to determine conditions under which moderate drinking could be maintained for 5 days in succession. The reinforcer for moderation was participation in an enriched environment. Excessive drinking resulted in the subject's withdrawal from this environment. The first experiment demonstrated that moderate drinking could be maintained by this strategy. The question arose then whether drinking during the noncontingent weeks occurred because of the absence of contingencies or whether it resulted from the aversive nature of the impoverished environment in which the subjects were required to live. The second experiment demonstrated that it was the absence of reinforcement contingencies for moderation, rather than living in an impoverished environment, which resulted in excessive drinking. These results are discussed in relation to the feasibility of moderate drinking as a therapeutic goal for the chronic alcoholic and contingencies which might be used to manage alcoholism.
78 citations
TL;DR: Sleep data from chronic alcoholics have indicated that sleep disturbance represents an important aspect of alcoholic detoxification, and previous studies have been complicated by problems of poor diet, uncertain time for onset of withdrawal, or a limited time schedule for controlled withdrawal.
Abstract: Sleep data from chronic alcoholics have indicated that sleep disturbance represents an important aspect of alcoholic detoxification. Previous studies have been complicated by problems of poor diet, uncertain time for onset of withdrawal, or a limited time schedule for controlled withdrawal. This stu
71 citations
62 citations
53 citations
TL;DR: It is found that, in vitro, ara-C incorporation was limited to the 3′-hydroxyl end of DNA chains and might be expected to block further chain elongation but this expectation was not supported by the evidence presented by Graham and Whitmore.
Abstract: Kimball and Wilson1 reported that the arabinose analogue of cytidine (ara-C) inhibited DNA polymerase in a crude extract prepared from Ehrlich ascites cells. Furth and Cohen2 observed cytosine arabinoside triphosphate (ara-CTP) inhibited DNA polymerase in extracts from either calf thymus or bovine lymphosarcoma tissue, although these investigators3 had already found no effect of ara-CTP on DNA polymerase from Escherichia coli. The inhibition in both of these cases could be substantially reversed by dCTP; but incorporation of the arabinose nucleotide (ara-CMP) into DNA could not be unequivocally demonstrated. Graham and Whitmore4 reported the incorporation of ara-C into DNA in vivo and the inhibition of a DNA polymerase from L cells by ara-CTP. They found that ara-CMP was initially incorporated into small DNA strands but subsequently appeared in long strands. Momparler5 has presented evidence that, in vitro, ara-C incorporation was limited to the 3′-hydroxyl end of DNA chains. Such incorporation might be expected to block further chain elongation but this expectation was not supported by the evidence presented by Graham and Whitmore.
44 citations
TL;DR: The number and arrangement of myofilaments and the ultrastructure of the Z band are consistent with the function of these muscles.
Abstract: Striated visceral muscle cells are scattered singly or in small groups at the base of the intestinal cells of the mid-gut of Drosophila melanogaster larvae. Fibers less than 1 μ in diameter, designated as small, contain a single myofibril, few, if any, dyads and few mitochondria. Fibers of somewhat larger diameter contain dyads and more mitochondria. Both types of fiber have a perforate Z band which appears as discontinuous bodies in longitudinal sections and as a perforate sheet of dense rims and clear perforations in transverse sections. The Z rims contain filaments, 30 to 50 A, oriented in the transverse direction. The number and arrangement of myofilaments and the ultrastructure of the Z band are consistent with the function of these muscles.
39 citations
TL;DR: The physician must go beyond the physical deformities and consider the many psychologic, social, economic, and vocational problems besetting a cancer patient and his family.
Abstract: In the treatment of cancer not only of the breast but of other anatomic areas as well consideration must be given to both the quantity and the quality of success Physical problems can result from any type of cancer therapy Complications such as brachial plexus injury or lymphedemia can develop and can have tremendous psychologic effects These physical problems must be recognized early Every effort must be made to minimize the resultant defects whether by preventive or definitive means The primary goal of treatment must be control of the disease but the complications of such treatment can no longer be ignored Utilization of available rehabilitation facilities to prevent or alleviate these complications must be considered more than in the past However the physician must go beyond the physical deformities and consider the many psychologic social economic and vocational problems besetting a cancer patient and his family It is beyond the realm of any single physician to accomplish this goal Ancillary medical and paramedical personnel must help to achieve this end Every opportunity must be given the cancer patient to continue his life in dignity rather than in despair(AUTHORS MODIFIED)
36 citations
TL;DR: The technique of starch-gel electrophoresis with specific staining for a series of enzymes was used to compare 21 Pseudomonas strains representing both P. cepacia and P. solanacearum, and the data indicate that these strains belong in two biotypes.
Abstract: The technique of starch-gel electrophoresis with specific staining for a series of enzymes was used to compare 21 Pseudomonas strains representing both P. cepacia and P. solanacearum. These experiments produced no evidence for close similarity of the two species. Twelve strains of P. solanacearum were compared by means of data obtained from nine different enzymes, and the data indicate that these strains belong in two biotypes. Except for the assignment of two strains, these groups are the same as the two major groups previously derived from nutritional properties and from deoxyribonucleic acid hybridization experiments. Eleven enzymes were available for comparisons of the P. cepacia strains. Eight of these strains form a homogeneous group, but the last strain, number 249, differs considerably from the other representatives of the species.
TL;DR: Carcinomatous metastasis to the testis is a rare disease and the authors review their experience with such a circumstance.
Abstract: Carcinomatous metastasis to the testis is a rare disease. The authors review their experience with such a circumstance.
TL;DR: Histone biosynthesis, measured by the incorporation of [ 14 C]lysine, increases considerably during the regeneration of rat liver, which precedes the peak of DNA replication and all of the histones are phosphorylated proportionately to their rates of biosynthesis.
TL;DR: In the basal and/or suprabasal cell layers of human and rat gingiva, specialized epithelial cells (Merkel cells) were rarely observed with the electron microscope, and the specialization of gingival Merkel cells as receptors did not appear to be as high as the epidermal Merkel cells.
TL;DR: In this article, the authors show that, after prolonged intoxication, at least 2 weeks of detoxification are required for most metabolic functions to return to normal, while continuous administration of 256 gm of ethanol, however, delayed the recovery of anemia and hyperuricemia in some patients.
Abstract: Fifty-six male alcoholic patients were admitted to the Metabolic Research Unit following prolonged intoxication. Seventeen patients were maintained on a normal protein diet and ethanol. Thirty-nine patients were placed on a normal diet without ethanol. Serial determinations of hemoglobin, platelets, serum transaminases, and uric acid were obtained at admission and once weekly thereafter. On 17 patients daily determinations of urine nitrogen excretion were obtained and in 31 patients 72-hour collections of stool were obtained for nitrogen and fat. The data show that there is a high incidence of metabolic abnormalities, and recovery, as measured by these tests, is delayed from 1 to 4 weeks. Improvement in dietary intake, rather than the complete withdrawal from ethanol, appeared to be more important in the recovery of normal nitrogen balance, body weight, stool fat, thrombocytopenia, and serum transaminases. The continuous administration of 256 gm of ethanol, however, delayed the recovery of anemia and hyperuricemia in some patients. The data show that, following prolonged intoxication, at least 2 weeks of detoxification are required for most metabolic functions to return to normal.
TL;DR: The amplitude and latency of the averaged visual evoked response (VER) recorded from the area of the occiput in man was found to be related to the rate of alternation and the spatial frequency of the alternating barred pattern used to elicit the responses.
TL;DR: Gehan and Siddiqui as discussed by the authors proposed a method to estimate the parameters of four survival distributions by least squares procedures and select the one which fits the data best. But the method is limited to a set of grouped survival data which may contain censored observations.
TL;DR: Computer trend-surface mapping techniques in conjunction with a statistical evaluation of suspended paniculate data from Houston, Texas, 1968 and 1969 are presented as a basic method for evaluation of progress toward a clean air environment.