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Biomedical subjects

W D Anderson

Publications and source records attributed to W D Anderson.

At least 37 records · Page 2Linked to original sources
PubMed1989

Arterial supply and venous drainage of the brain of the black bear (Ursus americanus). II. Intracranial microvasculature.

A morphological study of the intracranial microvasculature of the Black bear (Ursus americanus) using vascular casts was undertaken. The object was to provide basic information regarding structural modifications of the microvasculature that might provide insight into the ability to cope with low blood flow states that occur during winter sleep. Vascular casts were prepared from 6 animals. The microvasculature of the brain disclosed characteristic features of the small vessels in mammals, including vascular sphincters of two types and numerous arterial and arteriolar anastomoses.

Animals↗
PubMed1988

The effect of methanol and temperature on the kinetics of refolding of ribonuclease A.

Unfolded ribonuclease A consists of 20% fast refolding (Uf) and 80% slow refolding material (Us). The latter consists of at least two different forms which refold at different rates. We have used absorbance and fluorescence spectrophotometry to compare the kinetics of refolding in aqueous and aqueous-methanol solutions. At 1 degree C and pH 3.0, the addition of increasing concentrations of methanol (to 50%, v/v) had negligible effect on the rates and amplitudes of the slow refolding Us states. The effect of temperature on the two slow phases of refolding was determined in 35 and 50% methanol. From Arrhenius plots the energies of activation were found to be in the vicinity of 20 kcal/mol for both processes. The results suggest that both slow phases correspond to proline isomerization, and that the presence of methanol does not significantly perturb the overall refolding process. It is possible that the faster of the slow refolding phases corresponds to the isomerization of a proline residue which is trans in the folded native state but which undergoes extensive isomerization to the cis conformation in the unfolded state.

Hydrogen-Ion Concentration↗
PubMed1988

Evaluation of a QRS scoring system for estimating myocardial infarct size. VI: Identification of screening criteria for non-acute myocardial infarcts.

Each of the 54 criteria in the Selvester 32-point QRS scoring system for estimation of myocardial infarct (MI) size has attained greater than or equal to 95% specificity in normal subjects. This study was performed to identify a subset of those criteria with cumulative specificity greater than or equal to 95% and maximal sensitivity for use in screening for the presence of non-acute MI. Coronary angiography and left ventriculography were used to identify 500 normal subjects, 60 patients with isolated anterior MI and 62 patients with isolated inferior MI. Patients with the QRS confounding factors of ventricular hypertrophy, fascicular block or bundle branch block on their electrocardiogram were not included. Using stepwise logistic regression analysis, the screening criteria identified were: (1) Q greater than or equal to 30 ms in aVF, (2) R less than or equal to 10 ms and less than or equal to 0.1 mV in V2 and (3) R greater than or equal to 40 ms in V1. Cumulatively, these 3 screening criteria achieved 84% and 77% sensitivities for inferior and anterior MI groups, respectively. Thus, a set of 3 criteria from the Selvester QRS scoring system is capable of identifying single non-acute anterior or inferior MI in 80% of patients, and falsely indicating presence of MI in only 5% of normal subjects.

Adult↗
PubMed1988

Trapping the fast-refolding state of ribonuclease A at subzero temperatures.

Unfolded ribonuclease A consists of a mixture of fast- and slow-refolding species. It is generally accepted that the slow-refolding states arise from isomerization of proline residues. We show that unfolding at subzero temperatures may be used to trap the fast-refolding species Uf, since the rate of proline isomerization slows down at a much faster rate than protein unfolding. The unfolding was carried out in 5 M guanidine hydrochloride; at -15 degrees C the protein unfolding process is complete within 30 s and under these conditions there is less than 1.5% proline isomerization. By using ribonuclease in which Tyr-115 was nitrated it was possible to rule out significant isomerization of Pro-114 in the observed slow-unfolding step.

Animals↗
PubMed1988

Microvasculature of the bear heart demonstrated by scanning electron microscopy.

Morphological features of the coronary microvasculature were examined in ten Black bears (Ursus americanus). Tissue samples were collected for scanning electron microscopy from five animals, and vascular casts of the coronary vessels were prepared from five. Each portion of the microvasculature examined had specific morphological characteristics which may contribute to the control of blood flow. All indications from the present study suggest that the structure of the coronary microvasculature in the Black bear is similar to that of mammalian species previously examined.

Animals↗
PubMed1988

Renal microvasculature of the black bear (Ursus americanus).

This study of the Black bear (Ursus americanus) was undertaken to provide basic information related to structural modifications in the renal microvasculature that might provide insight into the drastic alteration in renal urinary output that occurs during winter sleep. Vascular casts, as well as light microscopy and scanning electron microscopy, were used to study the vascular components of the juxtaglomerular complex and related vessels. Histologically, arterial cushions were readily identified at the origin of the afferent arterioles. In the area of the juxtaglomerular complex, the wall of the afferent arteriole appeared to be highly modified. The smooth muscle cells at this site demonstrated a change in morphology and orientation, and the diameter of the arteriole was altered. The pattern of the vascular casts at the origin of the afferent arteriole varied from that portion at the glomerulus, suggesting a modification of the vascular wall near the renal corpuscle. Although the morphology of the renal microvasculature of the Black bear is similar to that of other mammals in some aspects, it is dissimilar to that of other carnivores and of the human kidney in that there are structural modifications of the afferent arteriole that may contribute to a reduction of blood flow to the nephron during winter sleep.

Animals↗
PubMed1985

Evaluation of a QRS scoring system for estimating myocardial infarct size. V. Specificity and method of application of the complete system.

The specificity of a previously developed 57-criteria/32-point QRS scoring system for estimating myocardial infarct (MI) size is evaluated in an extensive control population and the method of application of this system for determining a QRS score from a standard 12-lead electrocardiogram is described. Points are accumulated from Q- and R-wave durations, R- and S-wave amplitudes, R/Q- or R/S-amplitude ratios and the presence of R-wave notching, with each point representing approximately 3% of the left ventricle. The subjects were selected because of the minimal likelihood of their having had myocardial infarcts or other sources of QRS modification. There were 500 consecutively selected normal Caucasian subjects, aged 20 to 69 years, with 50 women and 50 men in each of the 5 decades. Specificity for the 57 individual criteria ranged from 89 to 100%. Fifty-one criteria met the required standard of at least 95% specificity; of the 6 that failed, 3 were successfully modified to achieve this standard and 3 were eliminated. In the resultant 54-criteria/32-point complete system, the total population, as well as both women and men, required more than 3 points to attain at least 95% specificity. Subjects in each of the 5 decades met the specificity standard either at or below the level of more than 3 points. The point score at which 95% or greater specificity was attained for the 10 age/sex subsets varied.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Acute aortic thrombosis and antithrombin III deficiency in the nephrotic syndrome: a case report.

A 25-year-old Oriental woman with nephrotic syndrome was admitted to the United States Naval Hospital in Okinawa. She had acute aortic thrombosis, which was managed initially with bilateral femoral thrombectomy and calf fasciotomies. In the early postoperative period, increasing doses of heparin were required to maintain adequate anticoagulation. Hematologic evaluation revealed a deficiency of antithrombin III (AT-III). Such a deficiency has been recognized as occurring in nephrotic syndrome, most probably due to urinary loss of this serum protein. Five prior cases of acute aortic thrombosis have been described in the nephrotic syndrome, but only three reports of acute aortic thrombosis have been attributed to documented AT-III deficiency. Acute thrombosis due to AT-III deficiency may be confirmed by measuring decreased serum levels of this protein. Treatment is initiated with fresh frozen plasma and heparin, with subsequent utilization of oral warfarin.

Journal Article↗
PubMed1983

Intracapsular and intraosseous vascular supply to the mature dog's coxofemoral joint.

The intracapsular and intraosseous arterial supply to the mature dog's coxofemoral joint was investigated using a vascular injection, tissue-clearing technique in 6 mixed-breed dogs. Ascending arteries of the femoral neck, arising from an extracapsular vascular ring at the base of the femoral neck, penetrated the articular capsule and traveled subsynovially over the surface of the femoral neck. These intracapsular arteries formed an incomplete intracapsular vascular ring at the junction of the femoral head and neck. Bony components of the acetabulum, ie, ilium, ischium, and acetabular bones, received intraosseous vascular supply from the nutrient artery of the ilium and minute vessels entering nutrient foramina around the rim of the acetabulum. The femoral head received branches (epiphyseal arteries) from the ascending arteries of the femoral neck at the intracapsular vascular ring. Epiphyseal arteries formed anastomosing vascular arches of decreasing caliber up to the subchondral bone of the femoral head. The proximal femoral metaphysis, particularly the femoral neck, received vascular supply from 4 sources: (i) branches from the epiphyseal arteries on the surface of the physeal scar which descended, penetrating the physeal scar, (ii) distally directed branches from the intracapsular vascular ring, (iii) ascending nutrient vessels from the trochanteric fossa, and (iv) terminal branches of the ascending nutrient artery of the femur.

Acetabulum↗
PubMed1982

Extraosseous vascular supply to the mature dog's coxofemoral joint.

Blood vessels supplying the coxofemoral joint were identified and described in 8 healthy, mature dogs. An accurate representation of the blood vessels was obtained by intra-arterial methyl methacrylate injection and sodium hydroxide corrosion of soft tissues until only the pelvis, femurs, and casts of the blood vessels remained. The sources of vascular supply to the dog's coxofemoral joint, from most to least contributory, were the lateral circumflex femoral artery, the medial circumflex femoral artery, the caudal gluteal artery, the cranial gluteal artery, and the iliolumbar artery. In addition, important vascular relationships were demonstrated. Many blood vessels were associated with the periosteal surfaces of the coxofemoral joint in areas of muscular and articular capsular attachment; fewer vessels were present in areas of loose periosteal attachment. Also, extra-articular anastomoses were identified. The most significant anastomosis was an extracapsular vascular ring located at the femoral attachment of the articular capsule. The extracapsular vascular ring was formed by branches of the lateral and medial circumflex femoral and caudal gluteal arteries.

Animals↗
PubMed1980

Microvasculature of the canine heart demonstrated by scanning electron microscopy.

In previous studies, a marked diminution in left coronary flow during systole has been demonstrated. This phenomenon has been said to result from capillary compressin by the contraction of myocardium and perhaps also from active changes in the state of the smooth muscle in the wall of the coronary vessels. In order to determine the morphological factors involved in this occurrence, and to gain a three-dimensional concept of the myocardial microvasculature, casts were prepared by perfusion of the coronary arteries with methyl methacrylate. Because of the conditions of the perfusion, these casts were considered to demonstrate a state of muscular contraction. Following maceration, portions of the casts were prepared for scanning electron microscopy (SEM). Arterioles of larger diameter were characterized by the helical configuration of the vascular replicas. Smaller vessels were categorized according to their directional pattern and their diameter. The arterioles gave rise to numerous large-diameter capillaries and also to short vessels that were guarded by sphincters. True capillaries, in some cases guarded by precapillary sphincters, were packed in densely stacked parallel sheets with numerous short anastomotic connections between them. Postcapillary venules were found to enter at regular intervals into larger venules arranged perpendicular to the capillary sheets. Most of these characteristics were found to be consistent throughout the microvasculature. These structural features were considered to be factors in the active regulation of blood flow through the myocardial microvasculature.

Animals↗
PubMed1978

Scanning electron microscopy of microcorrosion casts; intracranial and abdominal microvasculature in domestic animals.

The use of methyl methacrylate corrosion casts prepared for portions of the vascular system has made it possible to examine numerous and extensive areas of microscopic structures on a 3-dimensional scale with the scanning electron microscope. By this means we have examined the arterial microvasculature of intracranial vessels among three domestic animal species. In addition, these vessels have been compared with the terminal branches of abdominal arteries in the dog. The results of this study suggest that the sphincteric control mechanisms of the vessels in the two regions may be structurally different from one another. In the case of the intracranial vessels, the terminal portion of the arteriole is continued by a precapillary arteriole composed of a chain-like series of muscular constrictions. This is most suitably described as a precapillary sphincter area, which terminates at the capillary. In the abdominal vessels, the precapillary arteriole is generally followed by a single precapillary sphincter at the origin of the capillary. These morphological characteristics may account, in part, for the difference in response of vessels in these two regions in hypovolemic shock.

Animals↗
PubMed1978

Shunting in intracranial microvasculature demonstrated by SEM of corrosion-casts.

The use of methyl methacrylate corrosion-casts has made it possible to examine the intracranial microvasculature on a three-dimensional scale with the scanning electron microscope. By this means we have compared regions of four cerebral and cerebellar arteries among three domestic animal species. The results of this study suggest that there are from one to three different levels of interarteriolar anastomosis between branches of the same or adjacent vessels. In the horse and ox anastomoses were demonstrated (1) at the level of the precapillary arterioles, (2) along the arterioles, and (3) between small pial arteries. In the dog only the first-named anastomoses were evident in this study. These morphological characteristics may explain in part, the shunting mechanism by which hypoxia may be reduced among intracranial capillary networks.

Animals↗
PubMed1977

Vasculature of the equine and canine iris.

Methyl methacrylic casts were prepared and tissue was freshly collected for histologic examination to compare the vascular supply and the structure of the vessels of the iris in the adult horse with those of the dog. In the horse, ciliary blood vessels divided in the iris and formed a complete major arterial circle of the iris. In the dog, the ciliary blood vessels divided in the ciliary body and, by means of recurrent branches, formed a complete arterial circle. From this circle, radial arteries extended toward the pupillary margin. The radial vessels in the horse were nearly straight and joined to form a prominent minor arterial circle of the iris at the level of the sphincter pupillae muscle. Radial blood vessels in the horse did not appear to be controlled by the sphincter muscles. Venous blood of the iris of the horse was carried to the ophthalmic vessels via 4 prominent vortex veins. Drainage from the iris of the dog was by way of 4 to 6 circular collecting veins in the ciliary region. From this site, blood passed either via the ciliary veins or via small vortex veins to the dorsal and ventral external ophthalmic and then to the ophthalmic plexus.

Animals↗
PubMed1976

Renal vasculature of the trout demonstrated by scanning electron microscopy, compared with canine glomerular vessels.

In order to gain additional information regarding renal circulatory patterns, we have used both ink and resin injections to study the arterial supply to the mesonephric kidney of trout. Arterial injections through the dorsal aorta with ink were made for histological preparations in which the length, termination and relationship of glomerular vessels were examined. Similar injections with methyl methacrylate were made in preparation of corrosion casts to provide us with gross replicas of the aortic branches to the kidney as well as casts of glomerular structure for scanning electron microscopy. The sequence of vessels through which arterial blood passed to the renal corpuscle and ultimately to the uriniferous tubules was traced. Each afferent arteriole was found to terminate in three to six branches which formed anastomosing circuits of capillaries; these vessels reunited at the hilum to form a single efferent arteriole. The efferent arterioles in trun traveled a short distance to peritubular capillary beds and sinusoids. Morphological evidence was found for preglomerular sphincter-like action only. The glomerular vessels were found to be similar to, although less complex than, those of the outer and mid-cortical regions of the dog kidney.

Animals↗