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Biomedical subjects

D Taylor

Publications and source records attributed to D Taylor.

At least 343 records · Page 19Linked to original sources
PubMed1991

Stimulation of vitellogenesis by pyrethroids in mated and virgin female adults, male adults, and fourth instar females of Ornithodoros moubata (Acari: Argasidae).

The effects of several pyrethroids on vitellogenesis, i.e., vitellogenin (Vg) synthesis and ovarian development in unfed mated female adults of Ornithodoros moubata were investigated. Survival of ticks treated with pyrethrin, resmethrin, and etophenprox was very low. Ticks treated with cypermethrin (CyM), fenvalerate (Fev), and flucythrinate (Flu) survived even when high concentrations were used. Vg titer in the hemolymph of unfed mated females was the same level on day 5 and about three times higher on day 10 after treatment with CyM, Fev, and Flu, as that of engorged adult females. CyM was the most effective in inducing vitellogenesis and was further evaluated in unfed virgin females, males, and fourth instars. CyM was shown to stimulate vitellogenesis in unfed virgin females adults. Oviposition did not occur but ovaries were well developed. CyM also was shown to stimulate Vg in the hemolymph of unfed and fed adult males; however, the Vg levels were very low compared to that of engorged adult females. Extremely high concentrations of Vg were observed in the hemolymph of female nymphs (fourth instar), particularly engorged nymphs, treated with CyM (10 micrograms). No ovarian development was observed in these nymphs. Vg stimulated by CyM was shown to be immunologically and electrophoretically the same as that of normal engorged females.

Animals↗
PubMed1991

Effects of juvenile hormone and its analogs on vitellogenin synthesis and ovarian development in Ornithodoros moubata (Acari: Argasidae).

Effects of juvenile hormones (JH) and JH analogs on the release of vitellogenin (Vg) into the hemolymph and ovarian development in unfed adult female ticks, Ornithodoros moubata (Murray), were investigated. Topical application of acetone solvent and injection of acetone or oils showed some increase in Vg titer in the hemolymph. Topical application of JH (JH I, JH II, JH III) and JH analogs (methoprene, S21149, S21150, and S31183) dissolved in acetone to unengorged adult females elevated Vg titer in the hemolymph but only to the same level as the acetone controls. These effects were independent of dose. Injection of JH (JH I, JH II, JH III) and methoprene dissolved in mineral oil also did not significantly increase the Vg titer in the hemolymph compared with the controls (mineral oil injection). Electrophoretic analysis of hemolymph from females 5 d after treatment topically or by injection with JH and JH analogs showed faint Vg bands which comigrated with Vg's (Vg-1 and Vg-2) of normal, engorged female hemolymph, but Vg bands were detected more clearly in the hemolymph samples that were collected greater than 2 wk after treatment. However, the same level of Vg also was detected in the hemolymph of females treated with acetone or mineral oil. Vg synthesis in females treated with JH and JH analogs was analyzed by in vivo labeling and fluorography, which showed that Vg synthesis was not induced by application of JH to unengorged females.

Animals↗
PubMed1991

Oculofacialbulbar palsy in mother and son: review of 26 reports of familial transmission within the 'Möbius spectrum of defects'.

We report a mother and son with 5th, 6th, 7th, and bulbar cranial nerve paralysis, who had two similarly affected relatives. None of them had primary skeletal defects. Twenty-six previous reports of familial cases within the heterogeneous 'Möbius spectrum of defects' were reviewed. When cranial nerve palsies were associated with a primary skeletal defect, familial transmission was not found. No recurrence was noted in 31 cases with cranial nerve palsies associated with oral abnormalities and limb defects. The term Möbius syndrome should be restricted to cases with congenital 6th and 7th nerve paralysis with skeletal defects, who have a low recurrence risk (2%). The features in an index case which may indicate a higher risk of recurrence are the absence of skeletal defects, isolated facial palsy, deafness, ophthalmoplegia, and digital contractures. A recurrence risk of 25 to 30% in these cases appears reasonable.

Adult↗
PubMed1991

Biochemical changes within a multiple sclerosis plaque in vivo.

Magnetic resonance spectroscopy (MRS) was performed on a superficial part of the brain containing a large multiple sclerosis (MS) lesion. Reduced levels of phosphocreatine (PCr) relative to adenosine triphosphate (ATP) were found suggesting an abnormality in energy metabolism, with an increase in the phosphodiester (PDE) peak. A follow up study 16 months later revealed reduction in size of the lesion on MRI and normal intracellular biochemistry by MRS. Four MS patients without visible superficial cerebral lesions showed no significant changes in phosphorus metabolism.

Adenosine Triphosphate↗
PubMed1991

Assessment of left atrial appendage function by transesophageal echocardiography. Implications for the development of thrombus.

BACKGROUND: The predilection of the left atrial appendage (LAA) for thrombus formation has long been known. METHODS AND RESULTS: We prospectively studied the two-dimensional echocardiographic and Doppler patterns of LAA function in 82 patients by transesophageal echocardiography. In the 63 patients in sinus rhythm, LAA area was measured during LAA diastole at the onset of the electrocardiographic (ECG) P wave (LAAmax) and after LAA systole at the ECG R wave (LAAmin) and LAA ejection fraction was calculated as (LAAmax-LAAmin)/LAAmax; peak Doppler velocity was recorded from the LAA outlet. The 58 patients in sinus rhythm without LAA thrombus were grouped according to left atrial size on transthoracic echocardiography; 39 patients had a left atrial size of less than 40 mm (group 1) and 19 had a left atrial size of 40 mm or greater (group 2). Five patients in sinus rhythm had LAA thrombus. In the 19 patients with atrial fibrillation or flutter LAAmax was measured independent of the ECG; three of these patients had LAA spontaneous contrast, four had thrombus, and one had both. Patients in sinus rhythm without LAA thrombus demonstrated a characteristic pattern of a contractile LAA apex and a noncontractile base with color flow and pulsed Doppler evidence of LAA emptying that coincided with the P wave. Patients in sinus rhythm with LAA thrombus had a mean +/- SD LAAmax (8.0 +/- 1.5 cm2) larger than that in group 1 (5.0 +/- 1.9 cm2) (p less than 0.01) but not group 2 (6.7 +/- 3.1 cm2), LAAmin (6.5 +/- 1.0 cm2) larger than that in both group 1 (2.3 +/- 1.5 cm2) and group 2 (4.2 +/- 2.7 cm2) (p less than 0.01), and LAA ejection fraction (17 +/- 11%) and LAA velocity (0.24 +/- 0.10 m/sec) less than those in both group 1 (55 +/- 21% and 0.48 +/- 0.24 m/sec, respectively) and group 2 (45 +/- 27% and 0.46 +/- 0.24 m/sec, respectively) (p less than 0.01). Patients with atrial fibrillation or flutter with LAA spontaneous contrast and/or thrombus had LAAmax (10.4 +/- 6.6 cm2) greater than that in patients with atrial fibrillation or flutter without LAA contrast and/or thrombus (6.8 +/- 3.0 cm2) (p less than 0.05). The LAA appeared as a static pouch in seven of eight of the former compared with in two of 11 of the latter. When attempted, Doppler demonstrated a recognizable fibrillatory LAA outflow velocity pattern in none of three in the former versus four of seven in the latter group. CONCLUSIONS: We conclude that the LAA has a characteristic pattern of emptying in sinus rhythm. LAA thrombus formation in sinus rhythm and atrial fibrillation is associated with both poor LAA contraction and LAA dilation.

Adult↗
PubMed1991

Quinapril, an angiotensin converting enzyme inhibitor, prevents cardiac hypertrophy during episodic hypertension.

Six control dogs, six dogs treated with 1.5 mg/kg b.i.d. quinapril, and six dogs treated with 8 mg/kg q.d. minoxidil underwent 6 hours daily of hindquarter compression for 9 weeks. Minoxidil significantly decreased baseline blood pressure (-17 mm Hg; p less than or equal to 0.01), whereas quinapril decreased baseline blood pressure 11 mm Hg but not significantly (p = 0.15). Hindquarter compression elicited blood pressure increases in all three groups (control +18, quinapril +13, minoxidil +19 mm Hg). After 9 weeks, left ventricular mass in control dogs increased 22% (p less than 0.004); a similar increase was seen in minoxidil-treated dogs (+22%, p less than 0.0001) but not in the quinapril-treated group (+4%, p less than 0.15). The increase in left ventricular mass in control dogs was concentric (increased epicardial volume only), whereas in the minoxidil group, the hypertrophy was eccentric (both epicardial and endocardial volumes increased). The minimal hypertrophy in the quinapril group was concentric (no change in epicardial, but a decrease in endocardial volume). Quinapril had little hypotensive effect, but prevented the development of left ventricular hypertrophy, whereas minoxidil did not prevent hypertrophy in spite of its hypotensive effect. The mechanism of this differential effect of direct vasodilation versus converting enzyme inhibition on left ventricular hypertrophy is not fully elucidated. The results with quinapril suggest that some antihypertensive agents may positively affect left ventricular hypertrophy in spite of the absence of a large effect on baseline blood pressure or on blood pressure reactivity.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

The sensitivity of antibody detection testing using pooled versus unpooled reagent red cells.

Evaluation of paternity (alleged father, mother, and child) can range from a straightforward resolution to a complex problem that cannot be resolved without family studies. We present a case of disputed paternity in which tests for crossreactive groups (CREcS) and antigen subtypes (splits) within the human leukocyte antigen (HLA) system could not be used confidently to prove or disprove paternity. Further analysis, red cell enzyme tests, enabled a final verdict and confirmed the current reliability of HLA antisera defining splits.

Journal Article↗
PubMed1991

Immunity to Onchocerca volvulus microfilariae in mice and the induction of cross-protection with O. lienalis.

Inbred CBA/Ca mice were vaccinated with Onchocerca volvulus or Onchocerca lienalis microfilariae (mf) and challenged 100 days later with the homologous or heterologous parasite. There was a major reduction in mf recoveries from immunised animals compared with controls when the sensitising and challenge infections were both of O. volvulus mf. Resistance was manifest within one week of challenge, and rose from an 87% reduction in recoveries on day 7 to a 96% reduction on day 15. Similar results were obtained for homologous sensitising and challenge infections with O. lienalis mf. Protection afforded by sensitisation with the heterologous parasite was also high, although the expression of resistance appeared to be delayed. Vaccination with O. lienalis mf led to a 45% level of cross-protection against O. volvulus at 7 days after challenge, which rose to 94% by day 15. Vaccination with O. volvulus mf stimulated cross-protection against O. lienalis at levels of 49% and 80% as measured 7 and 15 days after challenge. It is concluded that the mouse model may be of value in analysing immune responses directed against O. volvulus mf and that the cross-protection between Onchocerca species is an advantage that should be exploited in characterising the antigens involved.

Animals↗
PubMed1991

The effect of indomethacin on Achilles tendon healing in rabbits.

In a randomized, blind study, percutaneous tenotomy was performed on the right Achilles tendon complex of 32 male, New Zealand rabbits. The rabbits were placed in long-leg casts to approximate the tendon. Sixteen rabbits received oral therapeutic doses (1.5 mg/kg/day) of indomethacin elixir; the remaining 16 rabbits received no medication and comprised the control group. At two and six weeks following tenotomy, eight rabbits in each group were sacrificed and the Achilles tendon complexes were resected. Each tendon was evaluated for tensile force-to-failure by uniaxial tensile loading using an Instron Materials Testing Machine at a velocity of 0.85 cm/second. Histologic evaluation assigned the specimens to categories of either "relatively mature" or "relatively immature," based on the degree of cellularity, neovascularity, and collagen orientation that had occurred in the healing process. The mean force-to-failure two weeks post-tenotomy for the experimental group was 75.7 +/- 42.3 Newtons (N), and 96.6 +/- 35.2 N for the control group; at six weeks post-tenotomy, the mean force-to-failure for the experimental group was 165.5 +/- 34.3 N and 160.2 +/- 31.6 N for the control group. Statistical analysis revealed no significant differences in tensile force-to-failure or histologic appearance between the experimental and control groups at either time interval. These results suggest that indomethacin, and potentially other nonsteroidal antiinflammatory drugs, may be used in conjunction with a tendon injury without significantly affecting the early healing process.

Achilles Tendon↗
PubMed1990

Hemifacial spasm in infancy.

Three infants presented with the onset of hemifacial spasm after birth and at the age of 10 months. One patient was found to have occlusion of the straight sinus and large collateral veins at the base of the brain, presumably due to venous sinus thrombosis, supporting the concept of vascular compression of the facial nerve at its exit from the brain stem as a mechanism for the production of hemifacial spasm. The other patients each had an intrinsic mass compressing the fourth ventricle, located in the lower pons and extending into the cerebellar vermis and right cerebellar peduncle in one; in the other patient, the mass involved the cerebellar vermis and right middle cerebellar peduncle alone. These patients widen the etiologic spectrum of the syndrome and show that serious intracranial diseases may underlie hemifacial spasm in infancy.

Brain Neoplasms↗
PubMed1990

The in vivo biologic effect of interleukin 2 and interferon alfa on natural immunity in patients with head and neck cancer.

Given the association of deficient natural immunity with the risk of metastatic disease, the ability to activate natural killer cell function may have a therapeutic significance. The effect of continuous infusion of interleukin 2 plus intramuscular interferon alfa on natural immune status was, therefore, analyzed in eight patients with head and neck cancer. Also evaluated was the effect of interleukin 2-interferon alfa therapy on lymphokine-activated killer cell activity as well as total lymphocyte count, percent of lymphocyte subsets, and levels of both circulating immune complexes and antibody classes. Both the percent and absolute number of natural killer cells (ie, CD56+ CD3- lymphocytes) within peripheral blood as well as natural killer cell activity against K562 targets increased significantly with treatment. The remaining immune parameters were not significantly altered. The demonstrated capacity to modulate natural immune function supports the potential use of interleukin 2-containing regimens as a preventive measure against metastatic disease in patients with head and neck cancer.

Adult↗
PubMed1990

Joubert syndrome: a clinico-radiological study.

A characteristic malformation of the cerebellum, including dysgenesis of the vermis and enlargement of the fourth ventricle was observed on computed tomography (CT) in 16 children on review of our consecutive material. Seven of these children underwent magnetic resonance imaging (MRI) which showed hypoplasia of the brainstem in addition to cerebellar vermian dysgenesis. One child had, in addition, dysgenesis of the corpus callosum. All these children were developmentally delayed, and many had neonatal breathing abnormalities, congenital retinal dystrophy and supranuclear ocular motor abnormalities. Joubert's syndrome should be suspected in children in whom dysgenesis of the cerebellar vermis and hypoplasia of the brainstem is shown on CT or MRI.

Brain Stem↗