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Biomedical subjects

J R Allen

Publications and source records attributed to J R Allen.

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

Epidemic bullous impetigo in a nursery due to a nasal carrier of Staphylococcus aureus: role of epidemiology and control measures.

From September 14, 1981 to February 28, 1982, an epidemic of bullous impetigo caused by a penicillin/tetracycline resistant strain of Staphylococcus aureus, phage type 3A/3C, occurred in a newborn nursery in Louisville, Kentucky. Twenty of 1,181 (1.7%) infants at risk developed disease during the six-month epidemic period. Clinically all case-infants had bullous impetigo skin lesions. One infant developed staphylococcal septicemia. No infant died. An epidemiologic investigation identified a nurse as having significantly greater contact with case-infants than control-infants (p = 0.0013). She was also found to be a nasal carrier of the epidemic strain. Infection control measures appeared to decrease infant-to-infant transmission via the hands of non-colonized nurses, but did not affect transmission from the nurse carrying the epidemic strain to infants. No cases of bullous impetigo have occurred since this nurse was temporarily removed from the nursery for treatment.

Anti-Bacterial Agents↗
PubMed1984

A nursery outbreak of multiple-aminoglycoside-resistant Escherichia coli.

In the neonatal intensive care unit (NICU) of one hospital, 16 infants became colonized or infected with multiply-resistant Escherichia coli (MR-E.coli) over an 8-month period. Isolates were obtained from blood, urine, and sputum of three patients and from rectal surveillance cultures of 13 patients. The one patient with the blood isolate died. A matched case-control study identified continuous feeding (nine of 16 cases vs. one of 16 controls, p less than or equal to 0.001) and receipt of aminoglycosides (p less than or equal to 0.03) as risk factors. For case-babies not exposed to continuous feeding, duration of bolus feeding was significantly greater than for their controls (cases, 22 days; controls, 7 days; p less than or equal to 0.02). All 16 isolates were the same serotype and were resistant to amikacin, tobramycin, kanamycin, and gentamicin. The epidemiologic investigation suggested that MR-E. coli may have spread from person-to-person on the hands of personnel and that MR-E. coli persisted in the NICU for 8 months until effective control measures were instituted.

Aminoglycosides↗
PubMed1984

Significant changes in epidermal Langerhans cells of guinea-pigs infested with ticks (Dermacentor andersoni).

Resistance to tick feeding has previously been shown to be an acquired, immunologically mediated phenomenon in guinea-pigs, associated with cutaneous basophil hypersensitivity to tick antigens. In this study, Langerhans cells (LC) in the epidermis of guinea-pigs were monitored during tick infestations of susceptible and resistant animals. A specific adenosine triphosphatase (ATPase) staining technique was used to identify epidermal LC. The numbers of LC decreased significantly around the sites of tick attachment during primary infestations. Early in the secondary infestations, increases in numbers of LC were observed in the epidermis surrounding tick mouth-parts. These changes in LC populations resemble those previously described in contact dermatitis reactions of guinea-pigs.

Adenosine Triphosphatases↗
PubMed1984

Effects of ultraviolet irradiation on epidermal Langerhans cells in guinea-pigs.

There is good evidence to suggest that u.v. irradiation (UVB) of the skin causes a reduction in the numbers of normal epidermal Langerhans cells (LC) in man and mouse. Little information is available on the effects of u.v. radiation on LC in guinea-pig skin. In this study, different dosages of UVB and UVC were applied to the ear skin of guinea-pigs. UVC irradiations were found more effective than UVB in causing depletions of ATPase-positive epidermal LC. Highly significant depletions, lasting 6 days after irradiation, were produced with little evidence of significant inflammatory reactions occurring in the epidermis.

Adenosine Triphosphatases↗
PubMed1984

Effects of ultraviolet irradiation on the acquisition and expression of tick resistance in guinea-pigs.

In guinea-pigs it has been shown that resistance to ticks is an acquired, immunologically mediated phenomenon. It has been suggested recently that epidermal Langerhans cells (LC) may play roles in the mechanisms of resistance to ticks. The ATPase-positive epidermal LC of guinea-pigs have been shown to be depleted for a period of several days following u.v. irradiations. In this study, u.v. treatment of guinea-pigs' ears before primary tick infestations resulted in a significant reduction of acquired resistance to ticks. When u.v. treatments were applied to resistant animals prior to the challenge infestations, a marked reduction in expression of resistance to ticks was demonstrated. These results can be interpreted to imply that functional LC in the epidermis are required for both the normal acquisition and the expression of the guinea-pig's immune responses to D. andersoni infestations.

Animals↗
PubMed1984

Glycogen depletion patterns in horses performing maximal exercise.

Muscle biopsy samples were collected from the left middle gluteal muscle of horses participating in competitive barrier trials. Twelve horses were biopsied the day before and within 30 minutes of completion of an 800 m barrier trial. A further six horses were sampled the day before, and within 30 minutes of, completion of a 1200 m barrier trial. Serial muscle sections were examined histochemically for myosin adenosine triphosphatase activity after acid preincubation, to demonstrate type I, IIA and IIB fibres. The glycogen content in the individual fibres was assessed using the periodic acid Schiff (PAS) reaction. Total glycogen in muscle was measured fluorimetrically after hydrolysis to glucose. Significant decreases in total muscle glycogen levels of 167.1 +/- 22.2 and 158.1 +/- 23.2 mmoles glucose units kg-1 (dry weight) (mean +/- standard error) occurred from pre- to post trial samples for horses in both 800 and 1200 m trials respectively. There were no significant differences between the decreases in total muscle glycogen from horses in either 800 m or 1200 m trials. In both 800 m and 1200 m trials there was a significant decrease in the percentage of type IIA and IIB fibres classified as having high PAS staining intensity, and a significant increase in the percentage of fibres classified as having medium staining intensity when samples taken after the trial were compared to those taken before the trial.

Animals↗
PubMed1983

Gouty involvement of a flexor tendon in the hand.

Gouty tenosynovitis is a well-recognized entity. However, its presentation as a localized mass in the palm is unusual and often not considered in the differential diagnosis. We report a case in which a localized deposit of urate crystals in a flexor tendon presented as a discrete palmar mass.

Adult↗
PubMed1983

In vitro feeding of Dermacentor andersoni (Stiles): effects of histamine and other mediators.

Female Dermacentor andersoni were induced to feed on defibrinated bovine blood through fixed mouse skin membranes. Their feeding behaviour was recorded electronically, the tick being incorporated into the circuit and acting as a variable resistor during the periods of sucking, salivation and rest. Recordings of the feeding behaviour of these ticks were similar to those of ticks feeding on rabbits. Known concentrations of histamine, serotonin, dopamine, prostaglandin E1 and prostaglandin F2a were added singly or in combination to the feeding medium of ticks attached to the mouse skin membrane. Addition of both histamine and serotonin was followed by a significant reduction in the amplitude or recordings associated with sucking and salivation. The concentration of mediators producing this effect was less than 10 mM, a concentration comparable to that of histamine found locally in the skin of tick-resistant guinea-pigs. Comparisons are made between the effects produced by these mediators in ticks and the effects of serotonin and other amines known to produce modulation of complex behaviour patterns in other invertebrates.

Animals↗
PubMed1983

Studies on isoxsuprine hydrochloride for the treatment of navicular disease.

A peripheral vasodilating agent, isoxsuprine hydrochloride, administered as an oral paste, was evaluated to determine its efficacy for the treatment of navicular disease. In a clinical trial, 13 horses with navicular disease were treated at a dose rate of 0.6 mg/kg body weight (bwt) twice daily for periods of six to 14 weeks. Twelve of the horses became completely sound while being treated, although two required a 50 per cent increase in dose. Nine of the horses have remained sound two to 10 months after ceasing therapy. In a controlled randomised double blind clinical trial, 16 horses with navicular disease were assigned to treatment with either a placebo paste or isoxsuprine paste for three weeks and then re-examined. All the horses treated with isoxsuprine showed improvement in gait, with seven of eight horses becoming sound, whereas only two horses treated with a placebo paste showed slight improvement. This difference in response was highly significant (P less than 0.001). To evaluate any physiological and biochemical effects of isoxsuprine, it was administered to five Standardbred geldings at dose rates of 0.6 mg/kg bwt and 1.2 mg/kg bwt. Complete blood counts, routine plasma biochemical parameters, cardinal signs and blood pressure measurements were performed up to 24 h after a single dose. No significant change in any of these parameters was found. To assess the peripheral vasodilatory action of isoxsuprine, infra-red thermography of the lower limb was performed before and up to 8 h after administration to horses. This revealed a significant increase in distal limb temperature which occurred from 90 to 480 mins after isoxsuprine administration. The maximum mean increase in distal limb temperature was 3.1 degrees C and this occurred 4 h after administration of the drug.

Administration, Oral↗
PubMed1983

Campylobacter enteritis in the United States. A multicenter study.

During a 15-month study, 8097 fecal specimens submitted to clinical microbiology laboratories at eight hospitals in different parts of the United States were examined. Campylobacter jejuni was isolated from 4.6%, Salmonella from 2.3%, and Shigella from 1.0%. Isolation rates for each pathogen were highest from stool specimens that were watery, bloody, or contained leukocytes. The peak isolation rate for C. jejuni was in persons ages 10 to 29 years; for Salmonella, in children younger than age 10 years; and for Shigella, in children ages 5 to 9 years. The clinical features of the three infections were nearly identical. In contrast, abdominal pain, bloody diarrhea, fever, tenesmus, and abnormal sigmoidoscopy findings were present significantly more often in patients infected with C. jejuni than in a control group of patients with diarrhea. Of patients with leukocytes in their stools and a history of fever, 45.9% were infected with one of the three pathogens. Use of laboratory and clinical findings defined groups with high or low risk of these three infections but could not accurately predict isolation. Fecal cultures had the highest yields when obtained from patients within 7 days from the onset of symptoms.

Adolescent↗
PubMed1983

Simplified technique for histochemical determination of three fiber types in equine skeletal muscle.

For determination of 3 muscle fiber types in equine skeletal muscle, a comparison of 2 preincubation buffers, each followed by myosin adenosine triphosphatase staining, was made. Serial sections of the muscle samples (n = 75) were preincubated in an acid buffer (pH 4.6) or a formaldehyde-glycine buffer (pH 7.25) and then were stained for myosin adenosine triphosphatase. Differentiation of muscle fibers into type I, IIA, and IIB was identical with both techniques; however, in the samples prepared at pH 4.6, type I fibers were black; type IIA, light gray; and type IIB, dark gray. In the samples prepared at pH 7.25, types I, IIA, and IIB fibers were white, light gray, and dark gray respectively. The formaldehyde-glycine preincubation buffer (at pH 7.25) gave more consistent results, was easier to prepare, and retained cytoarchitecture better, compared with the samples prepared at pH 4.6.

Adenosine Triphosphatases↗
PubMed1983

Effects of clenbuterol hydrochloride on certain respiratory and cardiovascular parameters in horses performing treadmill exercise.

Five standardbred geldings received intravenous clenbuterol hydrochloride and saline in a crossover experiment to evaluate the effects of clenbuterol on certain cardiorespiratory parameters during and after treadmill exercise. The exercise test consisted of four steps. Step 1 at a speed of 76 m per minute, step 2 at 129 m per minute, step 3 at 190 m per minute and step 4 at 236 m per minute. The duration of each step was two minutes, except step 4 which was four minutes. The treadmill was set at a grade of 19 per cent. Before exercise, 30 minutes after clenbuterol or saline administration, arterial and mixed venous blood gases, mean arterial pressure, mean pulmonary artery pressure, telemetric electrocardiogram and respiratory rate were measured. The measurements were repeated immediately before completion of step 2, step 4 and after one minute, 10 minutes and 30 minutes of recovery from exercise. After clenbuterol administration there was a transient fall in mean arterial pressure, which had returned to control values by 90 seconds. There was no change in mean pulmonary artery pressure. During exercise the heart rate was significantly higher at the end of steps 1 and 4 and after 10 minutes recovery when horses given clenbuterol were compared with those given saline. No adverse effects on the electrocardiogram were demonstrated. Effects of clenbuterol on blood gases included an increase in PaO2 and decrease in PaCO2 one minute after exercise, when compared to saline. It was concluded from the parameters examined that there was no evidence that clenbuterol had any significant untoward effect on the circulatory system of exercising horses.

Animals↗