Search PubMed⌕ Search

Biomedical subjects

L R Williams

Publications and source records attributed to L R Williams.

At least 127 records · Page 7Linked to original sources
PubMed1983

Persistent sciatic artery. Clinical aspects and operative management.

Abnormal persistent of the embryonic axial blood supply to the leg, the sciatic artery, is a rare but often clinically important condition. The sciatic artery may vary from a small collateral in the upper thigh to a very large vessel that is the leg's sole arterial blood supply. The abnormal artery is prone to aneurysmal dilatation and atherosclerotic occlusion, and different patterns of anatomic development in the sciatic and femoral artery systems pose significant diagnostic and therapeutic problems. Advances in preoperative hemodynamic assessment, arteriography, and vascular surgical technique have improved the results of management of persistent sciatic artery and its complications. The world literature has been reviewed, including one additional case, with emphasis on embryologic development, anatomic variations, and clinical presentation, as well as diagnosis, therapy, and results.

Adult↗
PubMed1983

Temporal changes of neuronotrophic activities accumulating in vivo within nerve regeneration chambers.

The presence of neuronotrophic factors (NTFs) in noninjured sciatic nerve extract and the course of their accumulation from 3 h to 30 days after nerve transection was examined. Rat sciatic nerves were transected and their proximal and distal stumps sutured into the openings of cylindrical silicone chambers leaving a 10-mm interstump gap. Previous studies had shown that regeneration occurs in chambers containing both stumps but is absent in chambers lacking the distal stump. Chambers became completely filled with fluid 10 to 12 h after implantation. Fluid from chambers without nerve stumps (open-ended) implanted adjacent to nerve-containing chambers had markedly lower trophic activities than those containing one or both stumps. In fluid collected from chambers containing both proximal and distal nerve stumps, the highest titers of NTFs directed to sensory neurons were measured at 3 h posttransection whereas the highest titers of NTFs directed to sympathetic and spinal cord neurons were detected at 1 and 3 days, respectively. Chambers containing only the proximal or only the distal stumps showed similar temporal dynamics for sensory and sympathetic NTFs. Sensory and sympathetic neuronotrophic activity in extracts of proximal and distal stumps followed a similar temporal course to those in chamber fluid. Extracts of nonlesion nerve segments 5 mm from the transection site contained higher sensory and lower sympathetic trophic activity than extracts including the transection site. Spinal cord activity was undetectable in all extracts. Antiserum to nerve growth factor had no effect on fluid or extracts containing high sensory or sympathetic activities. These observations suggested that (i) some NTFs may be present in normal nerves and others may be synthesized or accumulated in response to nerve injury, (ii) sensory, sympathetic, and spinal cord NTFs are separate agents and immunochemically distinct from nerve growth factor, (iii) NTFs predominantly originate from nerve stumps rather than from surrounding fluid, and (iv) proximal and distal nerve stumps accumulate and release NTFs at similar rates.

Animals↗
PubMed1983

The selectivity of beta-adrenoceptor antagonists on isoprenaline-induced changes in heart rate, blood pressure, soleus muscle contractility and airways function in anaesthetized cats.

The beta-adrenoceptor antagonist of propranolol, metoprolol, atenolol and butoxamine in anaesthetized cats has been measured and compared with the activity of four synthetic phenylethanolamine derivatives. The effects of isoprenaline on four parameters in the anaesthetized cat: heart rate, blood pressure, soleus muscle contractility and airway reactance, were measured and the modification of the isoprenaline dose-response relation by each of the antagonist drugs assessed. Parallel shifts in log dose-response curves for isoprenaline were caused by propranolol for all parameters, by metoprolol and atenolol for each parameter except blood pressure, and butoxamine for each except soleus muscle and heart rate. Selectivity of action of the antagonists between different organs was measured by comparing DR10 values, computed from isoprenaline dose-ratios. Propranolol was the most potent antagonist and showed slight selectivity of action on soleus muscle compared with heart. Atenolol and metoprolol were approximately equipotent and were cardioselective at low doses only. Butoxamine was the least potent antagonist and possessed non-beta-adrenoceptor effects on the parameters measured. Each of the new compounds, 4'-bromo-2'-methoxy-N-isopropyl phenylethanolamine, the 4'-chloro- and 4'-methyl analogues, and 4'-methoxy-N-t-butyl phenylethanolamine, was a potent antagonist but did not exhibit any selectivity of action. The results suggest no clear separation of beta-adrenoceptors into beta 1- and beta 2-subclasses in organs of the cat. There is no apparent separation of beta-adrenoceptor-mediated effects on skeletal muscle and airways.

Adrenergic beta-Antagonists↗
PubMed1983

Hemodynamic evaluation of the aortoiliac system based on pharmacologic vasodilatation.

Selection of the appropriate vascular reconstructive procedure in patients with multisegment disease requires the differentiation of aortoiliac from femoropopliteal occlusive disease and the detection of subcritical stenoses in the aortoiliac segment. Triplane arteriography and common femoral intra-arterial papaverine injection (30 mg) were done in 43 lower extremities in patients who subsequently had arterial bypass. The percent diameter stenosis was measured on the arteriograms and common femoral intra-arterial pressure was continuously monitored before and after papaverine injection. A resting femoral/brachial pressure index (FBI) was obtained and the percent decrease in this index (% delta FBI) was calculated using the maximum decrease in FBI following injection. Regression analysis revealed a significant correlation between % delta FBI and percent aortoiliac stenosis (r = 0.5446, P less than 0.005). In relation to clinical course, receiver-operator characteristic curve analysis revealed a % delta FBI of greater than or equal to 0.15 to be optimal in the detection of hemodynamically significant aortoiliac stenoses. When compared to clinical course, this % delta FBI was 88% sensitive, 100% specific, and 95% accurate. However, when analyzed with arteriography as the standard (50% stenosis), the same % delta FBI was only 70% sensitive, 100% specific, and 86% accurate. All limbs with a % delta FBI of 0.15 or greater improved following aortoiliac revascularization; 21% of these limbs had a normal preoperative resting FBI. No patient with a % delta FBI lower than 0.15 had improvement following aortoiliac revascularization. All limbs that had infrainguinal bypass had normal FBIs and % delta FBIs before bypass. After operation 90% of these limbs improved. Overall, this technique correctly predicted the clinical course in 95% of the limbs tested.

Aortic Diseases↗
PubMed1982

Increased penile perfusion and reversal of vasculogenic impotence following femoro-femoral bypass.

This study assessed the effect of femoro-femoral bypass on penile perfusion and impotence. Twelve patients with femoro-femoral grafts had Doppler pressure measurements and penile/brachial indices (PBI) recorded at both dorsal penile arteries, first with the graft open and then with the inflow portion of the graft temporarily occluded by manual external compression. Doppler pressure measurements and PBI did not change significantly in the dorsal penile artery on the donor (inflow) side of the graft when the graft was temporarily occluded. Patients who were potent both pre- and postoperatively (n = 5) had no significant change in pressure or PBI on the recipient (outflow) side of the graft with graft occlusion. In those patients who experienced reversal of impotence following bypass (n = 4) the mean dorsal penile artery pressure on the recipient side decreased from 101 mmHg with the graft open to 30 mmHg with the graft occluded (P less than 0.05). Review of arteriograms revealed that patients most likely to experience increases in penile perfusion have either (a) recipient side common iliac artery occlusion and a patent internal iliac system which is perfused in a retrograde fashion or (b) recipient side proximal internal iliac occlusion with well-developed collateral circulation between the profunda femoris and the distal internal iliac arterial systems. Femoro-femoral bypass can increase penile perfusion and alleviate vasculogenic impotence in selected patients.

Adult↗
PubMed1982

Derivatization of chiral amines with (S,S)-N-trifluoroacetylproline anhydride for GC estimation of enantiomeric composition.

The reaction characteristics of (S,S)-N-trifluoroacetylproline anhydride were examined in an attempt to develop a quantitative GC assay of the enantiomers of the sterically hindered, chiral amine ketamine. With the aid of the individual enantiomers of ketamine and the corresponding synthetic N-trifluoroacetylprolyl amides, it was found that the derivatization reaction proceeds stereoselectively, in poor yield, and with some degree of racemization of the acylating reagent. The results indicate that care must be exercised when prolyl derivatizing reagents are chosen for assaying chiral amines.

Amines↗
PubMed1982

Intraoperative assessment of limb revascularization by Doppler-derived segmental blood pressure measurements.

Prompt recognition and correction of technical errors in vascular procedures in the lower extremities decreases patient morbidity and improves the chances for successful revascularization. A simple, versatile technique for intraoperative hemodynamic assessment of lower extremity revascularization procedures is described. Salient features include ability to detect and correct technical errors without reoperation and its associated morbidity, use of commonly available, inexpensive equipment, and ease of performance without involvement of either specifically trained or inexperienced personnel.

Blood Pressure Determination↗
PubMed1982

Strontium-90 in bone: a case study in age-dependent dosimetric modeling.

There is an increasing need for age-dependent dosimetric models, and it would be desirable to develop these models in such a way that the uniformity and basic features of the standard man models are retained. Unfortunately, available data concerning the age-dependent retention of nuclides would rarely permit the identification of compartments, uptake fractions, and clearance times using the empirical fitting methods that characterize the development of many adult models. However, in cases where compartments can be made to correspond to physically identifiable processes or subsections within an organ, it may be possible to combine relatively extensive information concerning the development of the human body with generally sparse nuclide-specific information to construct age-dependent compartmental models. In some cases there may be sufficient data to identify trends with age within compartments using empirical fitting techniques, provided the compartments have already been identified on physical bases. To obtain models that describe changes in a continuous manner from birth through adulthood, it may be necessary in many cases to modify existing adult models to consider fewer (or more easily identifiable) compartments. In this article we describe an age-dependent model for retention of ingested 90Sr in bone that exemplifies these concepts.

Adolescent↗
PubMed1982

Utility of wide and narrow blood pressure cuffs in the hemodynamic assessment of aortoiliac occlusive disease.

One hundred lower extremities were evaluated by measurement of common femoral intra-arterial pressure and high-thigh Doppler-derived segmental pressures using wide and narrow blood pressure cuffs to assess the accuracy of high-thigh pressures in the evaluation of aortoiliac disease. Sixty-four extremities were also studied by arteriography. The results were analyzed using the common femoral intra-arterial pressure as the standard. The accuracy was poor for both the wide (52%) and narrow (73%) cuff techniques. No significant differences between the two techniques were evident in regard to the incidence of false positive (wide cuff, 75%; narrow cuff, 65%) and false negative (wide cuff, 3%; narrow cuff, 8%) tests. Superficial femoral artery disease was found to be responsible for all false positive tests using the narrow cuff technique (20 of 20) and all but one of the false positive tests using the wide cuff technique (34 of 35). These data indicate that segmental high-thigh pressures are useful primarily as a screening technique (low false negative rate) to exclude hemodynamically significant aortoiliac occlusive disease at rest.

Aortic Diseases↗
PubMed1982

Prebypass operative arteriography.

Complete arteriographic delineation of lower extremity arterial anatomy is not always possible preoperatively. Nonvisualization of patent arterial segments may lead to amputation in lieu of arterial bypass grafting. During a 3-year period (1978 to 1981), 31 patients evaluated for lower extremity arterial bypass had incomplete preoperative arteriographic studies. Eighty-seven percent of these patients were in limb salvage categories. In order to obtain better arterial visualization, 33 operative arteriograms, preceding 32 operative procedures, were performed through the femoral (n = 14), popliteal (n = 17), posterior tibial (n = 1), and dorsal pedial (n = 1) arteries. All arteriograms were performed following arterial dissection and clamp occlusion of arterial inflow. The operative arteriogram was found to be beneficial in 91% of cases (29 of 32). In 66%, bypass was performed to vessels that were not visualized preoperatively. In 25%, bypasses were performed to vessels that were visualized preoperatively but intraoperative arteriograms showed better visualization of the vessels and distal runoff, thus allowing bypass to the optimal recipient artery. In three cases (9%), the intraoperative technique was not beneficial, as no additional arterial visualization was provided. Only one patient could not undergo bypass because of nonvisualization of recipient vessels. Overall, major amputation was avoided in 86% of patients (24 of 28) suffering from severe rest pain or gangrene during the period of study. Prebypass operative arteriography is a technique that clearly provides for increased limb salvage. Ninety-three percent of patients (14 of 15) otherwise facing immediate major amputation had their limbs salvaged through the use of this technique.

Adult↗
PubMed1982

The effect of carotid siphon stenosis on stroke rate, death, and relief of symptoms following elective carotid endarterectomy.

It has been suggested that carotid endarterectomy for carotid bifurcation disease may be contraindicated in the presence of carotid siphon lesions. This study was undertaken to assess any difference in stroke rate, mortality, or relief of symptoms in patients with and without such "tandem" lesions following elective carotid endarterectomy. Ninety-one bifurcation endarterectomies were performed in 79 patients. The patients were divided into two groups. Group I (44 patients, 47 endarterectomies) had carotid bifurcation stenosis only; group I (35 patients, 44 endarterectomies) had siphon stenosis plus bifurcation stenosis. All patients in both groups who were symptomatic before operation were relieved of their symptoms. In group I there were no intraoperative or perioperative strokes, four late strokes (8.7%), one operate death (2.1%), and no late deaths. Group II patients had two intraoperative strokes (4.5%), three perioperative strokes (6.8%), two late strokes (5.1%), four operative deaths (9.1%), and three late deaths (7.5%). Eighteen of the 35 patients in group II had a greater degree of carotid siphon stenosis than bifurcation stenosis. In this subgroup, there was one operative stroke (5.6%), only perioperative stroke (5.6%), one late stroke (5.9%), one postoperative death (5.6%), and one late death (5.6%). None of these differences were statistically significant. Relief of symptoms was the same in patients with and without tandem carotid lesions, and there was no significantly increased risk of stroke or death following bifurcation endarterectomy in patients with tandem carotid lesions.

Adult↗
PubMed1981

Acyltransferase activity and cytochemical localization in differentiating neuroblastoma.

Acyltransferase (AT) enzyme activity was assayed biochemically and localized cytochemically in neuroblastoma monolayers to investigate the possible role of the enzyme in neuroblastoma differentiation and neurite extension. Treatment of cultures for 1 day with serum-free medium or Ro20-1724, a cyclic AMP phosphodiesterase inhibitor, induced neurite outgrowth but did not alter acyltransferase activity. Treatment for 4 days with dexamethasone or Ro20-1724 induced neurite outgrowth and a doubling of enzyme activity per cell. Chromatographic separation of lipid classes indicated that dexamethasone enhanced triacylglyceride synthesis. Acyltransferase was localized in mitochondria of neuroblastoma cells. The results show that 1) dexamethasone stimulates the storage lipid metabolic pathway in neuroblastoma cells and 2) increased acyltransferase activity is concomitant with dexamethasone-induced morphological differentiation. However, AT activity and neurite extension may not be causally related.

1-Acylglycerol-3-Phosphate O-Acyltransferase↗
PubMed1981

Glucocorticoids increase tyrosine hydroxylase activity in cultured murine neuroblastoma.

Cyclic AMP and glucocorticoids appear to have a role in regulating the activity of tyrosine hydroxylase (TH), as well as the expression of "morphological differentiation" in murine neuroblastoma. Monolayer cultures of C-1300 murine neuroblastoma (clone NBP2) were treated with the following compounds in ethanol: dexamethasone, triamcinolone acetonide, hydrocortisone, cortexolone, androstenedione, testosterone, estradiol-17 beta; or with the phosphodiesterase inhibitor Ro20-1724 [4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone]. Treatment with either 200 micrograms/ml Ro20-1724 or 50 micrograms/ml dexamethasone produced significant increases in TH activity compared to alcohol controls (1.44 vs. 0.82 nmol 14CO2/mg protein/hr compared to 0.095). Triamcinolone acetonide or hydrocortisone also produced smaller, but significant, increases in TH activity compared to dexamethasone. When steroid activities were compared at 25 microM concentration and after 60 min of incubation (to maximize TH activity), triamcinolone acetonide was not as effective (62%) as dexamethasone. The relatively inactive glucocorticoid cortexolone produced a slight but significant increase, while the androgens androstenedione and testosterone and the estrogen estradiol-17 beta were without effect.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed1980

Heritability of motor skill.

A total of 22 monozygotic (MZ) and 41 dizygotic (DZ) twin pairs were given 72 trials on a stabilometer balance task over six days to study the extent of the genetic contribution to learning and performance of a gross motor skill. The expectations that interindividual differences would be less for the MZ than for the DZ twins and that intraindividual variability would not be different between the two groups were supported. Intraclass correlations were used to provide estimates for the proportions of total phenotypic variance accounted for by heritability (h2), systematic environmental variance (E2), and nonsystematic environmental effects (e2). Heritability was found to be low during the early stages of learning, before it increased to stabilize at approximately 65% for the remaining practice. E2 was highest during these early stages (24%), then declined quickly to stabilize at half that level. Error variance (e2) constituted the remaining variance. Learning profiles of the twin pairs were also analyzed, with a greater intrapair resemblance being found for the MZ twins. The present findings indicate that, for gross motor skills, there is considerable potential for influencing both the levels of performance (and learning) and the differences between individuals by judicious use of systematic environmental effects.

Analysis of Variance↗
PubMed1980

Cardioselective beta-adrenoceptor blocking actions of some 2-methoxyphenylethanolamines in guinea pig tissues.

A series of new phenylethanolamines with 2-methoxy and/or 4-methyl, 4-chloro, or 4-bromo ring substituents and either N-isopropyl or N-tert butyl substituents have been synthesized and tested for beta 1- and beta 2-adrenoceptor blocking activity using isolated guinea pig atrial and tracheal preparations. Each of the disubstituted N-isopropyl derivatives was a potent antagonist, and the 2-methoxy-4-methyl derivative had a 40-fold beta 1/beta 2-receptor selectivity. Atenolol was shown to have a 32-fold selectivity in the same tests.

Adrenergic beta-Antagonists↗
PubMed1979

Urinary MHPG levels and tricyclic antidepressant drug selection. A preliminary communication on improved drug selection in clinical practice.

The 24-hour urinary 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) output was used as the basis for selection of tricyclic antidepressant drug therapy for the depressed patient population treated by one psychiatrist over a period of ten months in a psychiatric clinic. Use of MHPG output level as the criterion for drug selection resulted in significantly better clinical results than had been obtained previously by the same psychiatrist using more traditional selection methods on a similar depressed patient population. A correlation was noted between patients' pretreatment MHPG output levels and three symptoms of depression (guilt, agitation, and diurnal variation) as measured on the Hamilton Rating Scale for Depression.

Adult↗