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Biomedical subjects

T R Allen

Publications and source records attributed to T R Allen.

At least 19 recordsLinked to original sources
PubMed2001

Surgical treatment of a tomaculous neuropathy.

Compressive neuropathy of the ulnar nerve at the elbow is the second most common nerve entrapment in the upper limb. Eight possible anatomical points of constriction have been identified. The most common constriction being the intermuscular septum proximally or between the two heads of the flexor carpi ulnaris in the cubital canal distally. Surgical release is successful in 80-90% of cases. Certain rare genetic conditions can predispose susceptible peripheral nerves to similar compressive neuropathies but there is no literature on surgical treatment of such patients. We present a case of hereditary neuropathy with liability to pressure palsy (HNPP) often known as 'tomaculous' neuropathy, in a patient with ulnar nerve symptoms who underwent a surgical release.

Adult↗
PubMed2000

Echocardiography, color-coded Doppler imaging, and abdominal sonography, a non-invasive method for investigation of heart and aortic morphology and function in female gottingen minipigs: method and reference values for M-mode, B-mode, and flow parameters.

OBJECTIVE: The aim of the study reported here was to set up a method for echocardiography (EC) and abdominal sonography and to obtain EC reference values for left ventricular (LV) morphology and function and sonographic abdominal aortic morphology, function, and flow values in conscious, unsedated Gottingen minipigs. METHODS: Applying a standardized investigation procedure, the following parameters were measured by use of M-mode EC, color-coded Doppler imaging, and B-mode sonography, or were calculated, in 58 female minipigs: LV end-diastolic and end-systolic diameter, interventricular septum thickness, LV caudal wall thickness, LV end-diastolic volume and end-systolic volume, fractional shortening, ejection fraction, and percentage of thickening of interventricular septum and LV caudal wall. In addition, morphology, pulsatility, flow values, and flow patterns in the abdominal aorta were recorded or calculated during abdominal sonography and color-coded Doppler imaging. RESULTS: Variable EC values were obtained due to individual variations of motor activity. Variation could be reduced by accustoming the animals to a standardized investigation procedure. Reference values could be obtained for EC, partially indicating clear correlation with body weight. Color-coded Doppler and Doppler spectra did not indicate flow disturbances in large arterial abdominal vessels. CONCLUSIONS: Results indicate that handling during EC and sonography can cause discomfort in unsedated minipigs that may interfere with recording of valid reference values for functional cardiac parameters in young animals. Accustoming the animals to a standardized investigation procedure reduces stress to a satisfactory level and enables data recording. Thus the minipig is considered suitable for assessment of cardiovascular parameters in experimental or toxicologic studies.

Animals↗
PubMed1998

Effects of a standardized mistletoe preparation on metastatic B16 melanoma colonization in murine lungs.

The immune response-modifying drug Lektinol is a mistletoe preparation which is standardized with respect to bioactive viscum album agglutinin, the most active component of mistletoe. The present study was designed to evaluate the antimetastatic effects of this preparation following intravenous injection of B16 melanoma cells into mice. The standardized mistletoe extract was administered intravenously in doses of 100, 1000 or 5000 microliters/kg (equivalent to 3, 30 or 150 ng/kg of viscum album agglutinin) once daily for three weeks. An inhibition of mean pulmonary metastatic colonization of 58 to 95%, as measured by the number of melanoma cells on lung tissue slides, and a significant decrease of percentage of bronchoalveolar lavage pigmented cells were observed. In addition, a correlation of this antimetastatic activity with cellular immune parameters was investigated. In lavage fluids from the tumor-bearing mice, there was a 5 to 6-fold significant increase in the percentage of MAC-1+ (CD11b/CD18) immunocompetent macrophages in comparison with cells from vehicle-treated animals. The percentages of double-positive immature CD4+8+ thymocytes were significantly increased in animals treated with the standardized mistletoe extract. There were no signs of treatment-related toxicity. The results of this study indicate that the standardized mistletoe extract shows antimetastatic activity against B16 melanoma lung colonization.

Animals↗
PubMed1996

Pharmacological stress thallium scintigraphy with 2-cyclohexylmethylidenehydrazinoadenosine (WRC-0470). A novel, short-acting adenosine A2A receptor agonist.

BACKGROUND: Pharmacological stress imaging with adenosine or dipyridamole is associated with a high incidence of side effects, including hypotension, chest pain, AV conduction abnormalities, and bronchospasm. Although the desired coronary vasodilatory response is mediated primarily by the adenosine A2A receptors, these side effects result from stimulation of the A1, A2B, or A3 adenosine receptors. We hypothesized that a selective adenosine A2A receptor agonist would induce coronary vasodilatation appropriate for pharmacological stress imaging, without evoking adenosine receptor-mediated side effects. METHODS AND RESULTS: Infusions of a potent and selective A2A adenosine receptor agonist, WRC-0470 (0.1 to 3 micrograms kg-1. min-1 for 10 minutes), to five open-chest dogs produced dose-related left anterior descending (LAD) and left circumflex (LCx) coronary artery vasodilatation without altering mean arterial pressure, heart rate, left atrial pressure, or left ventricular dP/dt. In the same dogs, adenosine (300 micrograms . kg-1. min-1 for 4 minutes) produced coronary vasodilatation that was limited by significant hypotension. To determine the utility of WRC-0470 for pharmacological stress imaging, the hemodynamic responses to WRC-0470 (0.6 microgram.kg-1.min-1 for 10 minutes) and adenosine (250 micrograms.kg-1.min-1 for 4 minutes) were compared in dogs with critical LAD stenoses. 201T1 was injected at the peak WRC-0470 stress response. WRC-0470 increased LCx flow nearly fivefold but did not significantly lower mean arterial pressure. Anteroseptal defects were readily apparent in slice images from all dogs. The mean defect ratio (LAD/LCx) was 0.59 +/- 0.06. CONCLUSIONS: The potent A2A-selective adenosine receptor agonist WRC-0470 is a short-acting coronary vasodilator with potential utility for pharmacological stress perfusion imaging.

Adenosine↗
PubMed1981

The assessment of adolescent hallux valgus before and after first metatarsal osteotomy--clinical and walkway studies.

A comprehensive method of evaluating the feet of patients with adolescent hallux valgus both before and after surgical correction is described. Serial clinical, photographic and radiological studies were made and a dynamic assessment of gait was carried out using a load-sensitive walkway. Observations were made on 36 feet in which hallux valgus was treated by a modification of the Wilson oblique metatarsal osteotomy, with removal of a wedge of bone and screw fixation. In the first six months after operation, there was a lateral shift of the weight-bearing pattern in the forefoot and less weight was taken on the toes, but there was a tendency to return to the pre-operative distribution of weight during the next four years. Persistence of the lateral shift of weight-bearing appeared to result from elevation of the first metatarsal head secondary to shortening of the first metatarsal during the osteotomy. This can be avoided by deliberate depression of the first metatarsal head at the time of operation and fixation of the fragments in the required position with a screw.

Adolescent↗
PubMed1981

The intravenous toxicity of lentinan to the beagle dog.

The i.v administration of lentinan to the Beagle dog induced changes in the cytoplasm of macrophagic cells in the liver, spleen, kidney, lungs, lymph nodes, small intestine. Electron-lucent or filamentous inclusions were demonstrated in the liver, kidney and spleen. A dose level of 0.5 mg/kg/day was without adverse effect.

Animals↗
PubMed1978

Antibiotic prophylaxis in vascular surgery.

Preoperative and intraoperative antibiotic prophylaxis of infection in peripheral vascular surgery has been widely used although controlled studies have been lacking. A randomized, a prospective, double-blind study of cefazolin versus placebo during 565 arterial reconstructive operations was performed at this hospital from February 1976 through August 1977. Among the 462 patients undergoing surgery of the abdominal aorta and lower extremity vasculature, there was a highly significant difference in the infection rates: 6.8% for placebo recipients versus 0.9% for cefazolin recipients (p less than .001). Of the 18 infections, four involved vascular grafts and all four graft infections occurred in the placebo group. Over 8% of abdominal wounds of patients receiving placebo became infected versus 1.2% of cefazolin patients (p less than .05). Groin wounds were infected infrequently, 1.1% for placebo patients versus none for cefazolin patients. No infections occurred among 103 brachiocephalic procedures. Skin antisepsis was analyzed retrospectively. Infection rates were significantly higher (p less than .01) following hexachlorophene-ethanol versus a povidone-iodine skin preparation. Adverse effects of cefazolin were carefully monitored: no rash, phlebitis, or emergence of resistant strains was observed. A breif perioperative course of cefazolin and povidone-iodine skin antisepsis are recommended in vascular reconstructive surgery of the abdominal aorta and lower extremity vasculature.

Antisepsis↗
PubMed1977

Management of early postoperative complications of arterial repairs.

Of 1,703 patients undergoing arterial procedures during a three-year period, 81 (4.7%) required reoperation within 72 hours because of early complications. Thrombosis (58 patients) and hemorrhage (19 patients) were the most frequent complications encountered. Reoperation was successful in salvaging a successful outcome in the majority of patients after both hemorrhagic and thrombotic complications. The results seem to justify a continued aggressive approach to the management of early complications following vascular reconstructive procedures.

Aorta, Abdominal↗
PubMed1976

Arm veins for peripheral arterial reconstruction.

The ipsilateral saphenous vein has become accepted as the best available material for femoropopliteal bypass and for arterial patch grafts as well as for visceral and cardiac bypasses. However, in a few patients, nonavailability or nonsuitability of the saphenous vein forces use of some other material. We report an experience with 32 operations using arm veins. Among the 11 long vein grafts, seven composite vein-Dacron or vein-vein grafts, and 14 vein patch grafts during the past six years, there were no infections or aneurysms and only nine thrombotic failures have been detected to date, to our knowledge. Our present indications are (1) ipsilateral saphenous vein is not available or is not suitable, (2) only a short graft or patch is needed and the saphenous vein may therefore be saved for the future, (3) to join to a saphenous graft or to a Dacron composite graft for additional length, and (4) to reconstruct an arm artery. Our experiences using cephalic and basilic veins confirms them as a useful source of autogenous material for arterial reconstruction.

Adult↗