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Biomedical subjects

J R Allen

Publications and source records attributed to J R Allen.

At least 127 records · Page 7Linked to original sources
PubMed1986

Benzyl alcohol toxicity: impact on mortality and intraventricular hemorrhage among very low birth weight infants.

Benzyl alcohol preservative in intravascular flush solutions has been reported to cause neurologic deterioration and death in very low birth weight infants. Following the widespread discontinuation of the use of such solutions in newborns, scattered reports of decreased mortality and decreased incidence of intraventricular hemorrhage among small premature infants appeared in the pediatric literature. To better assess the true impact of benzyl alcohol toxicity in this group of infants, we undertook a detailed review of the medical records of all babies less than 1,250 g birth weight admitted to our neonatal intensive care unit for 13 months before and 13 months after the use of solutions containing benzyl alcohol was stopped. Significant decreases were found in both mortality rate (from 80.7% to 45.7%) and incidence of grade III/IV intraventricular hemorrhage (from 46% to 19%) among infants less than 1,000 g birth weight who did not receive the preservative compared with those who did. No significant changes were found in several other prenatal factors that could have contributed to this improvement in survival. We conclude that benzyl alcohol toxicity contributed significantly to both mortality and the occurrence of major intraventricular hemorrhage among infants weighing less than 1,000 g at birth and that solutions containing benzyl alcohol should never again be used in the care of such infants.

Benzyl Alcohols↗
PubMed1986

Effects of training on muscle composition in horses.

Biopsy samples were obtained from the middle gluteal muscle of 10 Thoroughbred horses undergoing a commercial race-training program. Samples were obtained before the program began and again after 6 and 12 weeks of training. All horses had raced at least once by the 12th week of training. Serial sections of muscle were examined histochemically for myosin adenosinetriphosphatase after either acid (pH 4.3 and 4.6) or alkaline (pH 10.3) preincubation, and then muscle fibers were identified as types I, IIA, IIB, or IIC. The oxidative capacity of individual fibers was assessed, using the reduced nicotinamide dinucleotide tetrazolium-reductase stain, and the number of intermyofibrillar capillaries adjacent to each fiber were counted after staining, using the alpha-amylase-periodic acid-Schiff technique. Biochemical analyses involved the fluorometric measurement of 3 enzymes--citrate synthase, 3-hydroxy-acyl coenzyme A dehydrogenase, and lactate dehydrogenase--as markers of end terminal oxidative, beta-oxidative, and glycolytic potentials, respectively. Changes in fiber-type percentages did not occur in response to training. There was a significant (P less than 0.01) increase in the percentage of type IIB fibers, having high nicotinamide dinucleotide-tetrazolium reductase staining after 12 weeks of training. Alterations in the number of capillaries adjacent to each fiber type did not occur during the training period. There were increases in the activities of both citrate synthase and 3-hydroxy-acyl coenzyme A dehydrogenase after 6 weeks (P less than 0.05) and 12 weeks (P less than 0.001) of training. Alterations in the activity of lactate dehydrogenase did not occur in response to training.

Animals↗
PubMed1985

Acquired immunodeficiency syndrome in New York City. Evaluation of an active surveillance system.

In January 1983, the New York City Department of Health initiated an active surveillance program for acquired immunodeficiency syndrome (AIDS) in 19 hospitals and a modified-active surveillance program in the remaining 69 hospitals. We reviewed hospital laboratory and autopsy records in 12 active surveillance hospitals and three modified-active surveillance hospitals six months later. Patients who had opportunistic diseases characteristic of AIDS diagnosed in 1982 (before active surveillance) and 1983 (after implementation of active surveillance) were matched against health department AIDS surveillance reports. For the 16 months we evaluated, 96% of patients identified with AIDS in the 12 active surveillance hospitals and 100% of those in the three modified-active surveillance hospitals had been reported to the health department. The delay between diagnosing a case and reporting it to the health department significantly decreased between 1981 and the first six months of 1983 in all hospitals. The proportion of cases reported within one month of diagnosis increased from 45% to 69% during this period. We conclude that the current surveillance program for AIDS in New York City is effective and that case reporting is sufficiently complete for accurate analysis of disease trends.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The incidence rate of acquired immunodeficiency syndrome in selected populations.

Population figures were obtained, and incidence rates of acquired immunodeficiency syndrome (AIDS) for the 12 months from June 1, 1983, to May 31, 1984, were estimated for single (never-married) men aged 15 years or older, intravenous (IV) drug users, Haitians living in the United States, persons with hemophilia A and B, female sexual contacts of male IV drug users, and blood transfusion recipients. Single men in San Francisco and Manhattan, IV drug users in New York City and New Jersey, hemophilia A patients, and recent Haitian entrants had the highest rates of disease (82.0 to 268.9 per 100,000). Male IV drug users and male Haitians were two to four times as likely to experience development of AIDS as were females in each group. Persons with hemophilia A had six times the incidence rate of AIDS as did those with hemophilia B. Persons with severe hemophilia A had three times the rate of those with moderate and seven times the rate of those with mild clotting factor deficiency. Although blood transfusion recipients and female sexual contacts of male IV drug users had much lower average yearly rates than did persons in the four other groups (0.4 to 9.4 per 100,000), they still had a higher incidence rate of AIDS than did persons not belonging to any of these groups (0.1 per 100,000).

Acquired Immunodeficiency Syndrome↗
PubMed1985

Comparison of fiber types in skeletal muscles from ten animal species based on sensitivity of the myofibrillar actomyosin ATPase to acid or copper.

Comparisons were made of the histochemical characteristics of skeletal muscle from 10 animal species. The basic comparison was made from the staining patterns for the myofibrillar actomyosin ATPase produced by preincubation of fresh frozen cross-sections of muscle at alkaline pH (10.30) or acid pH (4.60) with those produced by preincubation in media containing Cu2+ at alkaline pH (10.30), near neutral pH (7.40), or acid pH (4.60). Muscle sections were also stained for reduced nicotinamide adenine dinucleotide tetrazolium reductase and alpha-glycerophosphate dehydrogenase to provide an indication of the relative oxidative and glycolytic capacity of the different fiber types. Type II fibers in mixed fibered muscles were either very sensitive, moderately sensitive, or relatively insensitive to inactivation of the myofibrillar actomyosin ATPase after acid preincubation. These fibers were identified as type IIA1, IIA2, and IIA3, respectively. The myofibrillar actomyosin ATPase of the type I fibers of these muscles, with the exception of those in mouse muscle, was activated by pretreatment with acid. A separation of animal species was possible based on the stability of the IIA1 fibers to inclusion of Cu2+ in the preincubation medium. For one group of animals (rat, mouse, monkey, man, dog, rabbit, and cow), a reciprocal relationship existed between lability to acid and stability to Cu2+ for type IIA1 and IIA3 fibers, respectively. For the second group of animals (horse, ass, and cat) there was a parallel relationship between lability or stability of the type IIA1 and IIA3 fibers to pretreatment with either acid or Cu2+.

Actomyosin↗
PubMed1985

Dermacentor variabilis: acquired resistance to ticks in BALB/c mice.

To assess the ability of Dermacentor variabilis larvae to feed on mice during repeated infestations, known numbers of larvae were confined to the skin of BALB/c mice within plastic capsules, and different skin sites were used in four successive infestations. In secondary infestations larval feeding appeared to be enhanced, but in subsequent infestations the mice expressed acquired tick resistance, manifested by reduction in numbers of engorged larvae and in weights of fed larvae. Resistance, once established, was still demonstrable four weeks after the previous infestation. Histological examination of skin biopsies from BALB/c mice undergoing repeated infestations revealed slight reactions to primary infestations and increasingly severe responses in subsequent infestations. The latter reactions included prominent participation of mast cells and eosinophils, many of which were degranulated close to tick bite sites. It is suggested that these cells might play a role in the expression of murine tick resistance.

Animals↗
PubMed1985

Dermacentor variabilis: resistance to ticks acquired by mast cell-deficient and other strains of mice.

The acquisition of resistance to ticks was monitored in mice of six different strains. Mice were subjected to repeated infestations with Dermacentor variabilis larvae, different skin sites being used for each successive infestation. In the third and fourth infestations, resistance was expressed in three strains of mice (WBB6F1-W/Wv, WBB6F1-+/+, and CFW), as demonstrated by significant reductions in percentages of larvae engorging and in mean weights of fed larvae. Both WBB6F1-W/Wv mice, which are mast cell-sufficient strain attained significantly higher levels of resistance. It is suggested that mast cells may play a relatively minor role in the mechanisms of resistance in this strain of mice. C57B1 mice also expressed tick resistance in their third and fourth infestations as measured by reduced percentages of engorged larvae, but not by reduced mean larval weights. Possibly, the mechanisms of tick resistance in this strain differ from those in other strains. Two other mouse strains (C3H-HeJ and C3H-HeSn) remained relatively susceptible to tick feeding throughout five infestations. In secondary infestations of all strains tested, no resistance was evident. Instead, enhanced feeding of larvae appeared to occur. A new objective measurement of tick resistance is the mean weights of detached, unengorged larvae taken from resistant animals at the end of the infestation period. These were found to be consistently less than those from susceptible animals.

Animals↗
PubMed1985

Hematologic responses to exercise and training.

Hematology has been widely used in attempts to provide information about disease states, performance problems, and fitness in performance horses. However, owing to factors such as the temperament of the horse and time of collection and feeding, considerable variation in the hemograms can be found. This article reviews some of the hematologic responses to exercise and training.

Animals↗
PubMed1985

Effects of a submaximal treadmill training programme on histochemical properties, enzyme activities and glycogen utilisation of skeletal muscle in the horse.

The effects of training on skeletal muscle composition were studied in four Standardbred geldings given a seven week submaximal treadmill training programme. Before the start of training, muscle biopsies were collected from the left middle gluteal muscle for the determination of muscle fibre types, oxidative capacity and capillary numbers using histochemical techniques. The concentrations of citrate synthase, 3-hydroxyacyl-CoA dehydrogenase (HAD), lactate dehydrogenase and total muscle glycogen were measured using fluorometric methods. Muscle biopsy samples were repeated after one, three, five and seven weeks of training and the same measurements performed. No significant changes were found in muscle fibre types or capillary numbers as a result of training, although there was an increase in the oxidative capacity of the Type IIB fibres after seven weeks training. After seven weeks of training there were also increases in the concentrations of citrate synthase and HAD and a decrease in lactate dehydrogenase. Before commencement of training the horses underwent a standardised submaximal exercise test and muscle glycogen concentrations were measured before and immediately after the exercise. This procedure was repeated after one, three, five and seven weeks of training. A progressive decrease in the rate of glycogen utilisation occurred throughout the period of training, which by seven weeks was 36 per cent lower than that before training.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1985

Glycogen depletion patterns in horses competing in day 2 of a three day event.

Muscle biopsy samples were collected from the left middle gluteal muscle of the horses participating in day 2 (speed and endurance test) of a three day event. Six Thoroughbred horses were biopsied the day before and within 30 minutes of completion of the speed and endurance test. Serial muscle sections were reacted histochemically for myosin adenosine triphosphatase activity after acid pre-incubation to demonstrate Type I, IIA and IIB fibers and the glycogen content in the individual fibers was assessed using the periodic acid Schiff (PAS) reaction. Total glycogen in muscle was measured fluorometrically after hydrolysis to glucose. A significant decrease (P less than 0.001) in total muscle glycogen of 306.0 +/- 34.6 mmoles glucose units/kg (dry weight) (mean +/- SE) occurred when samples collected before exercise were compared to those collected following exercise. A significant decrease (P less than 0.05) in the percentage of Type I fibers having medium PAS staining intensity occurred when pre and post-exercise samples were compared. Significant decreases (P less than 0.01 and P less than 0.001 respectively) in the percentage of Type IIA and IIB fibers classified as having high PAS staining intensity occurred when post-exercise samples were compared with those pre-exercise. There were significant increases (P less than 0.01 and P less than 0.001 respectively) in the percentage of Type IIA and IIB fibers classified as having medium PAS staining intensity when the samples collected after the exercise were compared with those before the exercise.

Animals↗
PubMed1985

Langerhans cells present tick antigens to lymph node cells from tick-sensitized guinea-pigs.

Resistance to the feeding activities of ixodid ticks has previously been shown to be an acquired, immunologically-mediated phenomenon in guinea-pigs, associated with cutaneous hypersensitivity to tick antigens. Also, there is circumstantial evidence to support the suggestion that epidermal Langerhans cells may play roles in the acquisition and expression of tick resistance. In this in vitro study, lymphocyte blastogenesis assays were performed using column-purified lymph node cells from naive or tick-sensitized guinea-pigs as responder cells. Syngeneic macrophages or epidermal Langerhans cells, incubated with tick salivary antigens, were used as stimulator cells. Epidermal cell populations, containing viable Langerhans cells, were prepared by two different protocols. Epidermal cell populations containing ATPase-positive, Fc receptor- and Ia-bearing cells (Langerhans cells), when incubated with tick antigen, produced detectable proliferative responses in responder cells from tick-sensitized guinea-pigs. Antigen-incubated, Ia-bearing macrophages produced similar responses. It is concluded that, as has been shown in man and the guinea-pig with other antigens, Langerhans cells, like Ia-bearing macrophages, can act as antigen-presenting accessory cells in the immunological responses of guinea-pigs to tick infestations.

Animals↗
PubMed1984

Pseudomonas fluorescens bacteremia from blood transfusion.

In October 1980, two units of blood contaminated with Pseudomonas fluorescens caused septic transfusion reactions in two recipients at a Chicago hospital; one patient died. Both units had been purchased from the same blood center. Investigation at the blood center and at other hospitals it supplied revealed another fatal case of P. fluorescens sepsis that had occurred one year earlier. Despite extensive environmental culturing at the blood center, the source of P. fluorescens was not identified. However, comparison of the interval between collection and administration of contaminated and non-contaminated units indicated that prolonged storage was a risk factor that may have caused clustering of cases in one hospital. Laboratory studies showed that small inocula of P. fluorescens proliferated in refrigerated fresh whole blood and reached 10(6) to 10(7) colony-forming units per milliliter seven days after incubation. These data suggest that prolonged storage of blood may be an important risk factor for the development of transfusion-related sepsis.

Adult↗