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Biomedical subjects

R A Williams

Publications and source records attributed to R A Williams.

At least 91 records · Page 5Linked to original sources
PubMed1994

Dose-response relationships in hepatic injury produced by alcohol and carbon tetrachloride.

Dose-response relationships were examined for the production of hepatic fibrosis and cirrhosis by combined exposure of male Porton rats to alcohol and carbon tetrachloride. Alcohol was administered orally in Lieber-DeCarli liquid diet at levels of 75, 150, or 300 kcal/liter, giving mean daily intakes of 2.29, 4.61, and 8.16 g/kg/day, respectively. Carbon tetrachloride was administered by inhalation at concentrations of 10, 20, or 40 ppm, 6 hr/night, 5 nights/week. Liver biopsies were taken at intervals up to a maximum treatment period of 20 weeks. All four rats that received the high dose of both agents, and 1 of 4 that received the medium alcohol and high carbon tetrachloride treatments, were cirrhotic by 10 weeks. Two of the 4 rats that received the low alcohol and high carbon tetrachloride dose were cirrhotic at 20 weeks. Cirrhosis was not observed in rats that received the low or medium carbon tetrachloride dose, but some degree of hepatic fibrosis was observed in all treatment groups. Severity of fibrosis was significantly associated with both dose of alcohol and dose of carbon tetrachloride received. It is concluded that, in the alcohol-carbon tetrachloride rat model for chronic liver injury, both alcohol and carbon tetrachloride contribute to the response in a dose-related manner. Hepatic injury was observed even when relatively low doses of these agents are administered together.

Alcohol Drinking↗
PubMed1993

A new restriction endonuclease, TspEI, from the genus Thermus that generates cohesive termini compatible with those of EcoRI.

The detection, isolation and properties of the restriction endonuclease TspEI are described. The canonical recognition sequence (AATT) is the same as the 4-bp core of the 6-bp sequence (GAATTC) of EcoRI. Hydrolysis occurs 5' to the palindromic tetramer so that TspEI produces the same cohesive termini as EcoRI. TspEI therefore has an obvious application in producing partial digests of DNA for ligation to EcoRI-digested cloning vectors.

Base Sequence↗
PubMed1993

Malignant potential of aneuploid pancreatic endocrine tumours.

Evaluation of the malignant potential of pancreatic endocrine tumours is difficult by histological criteria alone. Nuclear deoxyribonucleic acid (DNA) cytometric analysis can provide significant prognostic and biological information in a number of solid human tumours. Thus, the DNA profiles and nuclear parameters of 39 patients with pancreatic endocrine tumours diagnosed from 1969 to 1989 were studied, using computerized video image analysis. Of the 39 patients with tumours, 27 cases did not have evidence of metastatic disease at the time of investigation. The majority of these (N = 21) showed a diploid profile. Five were aneuploid and one was tetraploid. In the 12 tumours that proved malignant, three had tissue of both primary tumour and the metastases analysed; six had material only from the primary tumour, although metastatic disease was established clinically; and another three only had tissue from the secondary tumour studied. The majority of the malignant cases were aneuploid (N = 7); three were diploid; one showed a diploid primary but an aneuploid secondary, and one showed a hyperdiploid pattern. The percentage of nuclei with a DNA content greater than 5N (5CER) did not seem to contribute further to the assessment nor did the means of the nuclear areas and shape factors. It appears that ploidy studies may be useful in predicting malignant potential of pancreatic endocrine tumours. There is a high rate of immunostaining for insulin by benign pancreatic endocrine tumours and this may be a useful adjunct to distinguish them from their malignant counterparts. However, there is no statistically significant correlation between the expression of various hormones and the DNA ploidy of tumour cells.

Aneuploidy↗
PubMed1993

Isolation of infectious laryngotracheitis virus from proximal femora of lame broiler chickens.

Two herpesviruses previously isolated from seven of 19 affected joint/bone samples in an earlier survey of lameness in broilers were identified. They were characterised as infectious laryngotracheitis (ILT) virus using serum neutralisation, immunofluorescence, restriction enzyme analysis and polymerase chain reaction techniques. In experimentally infected chicks, one of the isolates caused mild ILT and intranuclear inclusion bodies were present in the tracheal epithelium after four days. It is considered unlikely that these viruses were involved in the pathological changes in the affected legs. The possibility that ILT pathogenesis and epidemiology are more complex than currently understood is discussed.

Animals↗
PubMed1993

Impact of endoscopic therapy on outcome of operation for bleeding peptic ulcers.

Since elective surgery for bleeding peptic ulcer disease has declined, the surgical opinion is that patients who undergo emergency operation have more advanced disease and possibly a poorer outcome. We examined current mortality for surgical correction of upper gastrointestinal (UGI) bleeding from peptic ulcer disease. Between July 1, 1986, and December 31, 1990, 1,213 patients had esophagogastroduodenoscopy for UGI bleeding (659 with peptic ulcer disease, 219 with gastroesophageal varices, 152 with esophagitis, 83 with other causes, and 100 with no source found). Of 110 patients with peptic ulcer disease treated by endoscopic methods, bleeding was controlled in 90, and 20 required operation for failed endoscopic control. Another 22 patients had primary operation for exigent bleeding with diagnostic endoscopy only. The overall results in our series compared favorably with two pre-therapeutic endoscopy index series (Nottingham, 1982; University of Pittsburgh, 1982). Our operation rate was 6%, with a mortality rate of 7%, compared with operation rates of 15% to 27%, with mortality rates of 21% to 22% in the historical control series. In conclusion, we found that: (1) endoscopic control of UGI bleeding from peptic ulcer disease has decreased the incidence of operation compared with historical series; (2) overall operative mortality is decreasing; and (3) the major postoperative complication is rebleeding.

Adult↗
PubMed1993

Evaluation of access to care and medical and behavioral outcomes in a school-based intervention program for attention-deficit hyperactivity disorder.

The Project for Attention-Related Disorders (PARD), instituted by the San Diego (Calif.) School District. represents a unique approach to identification, referral, and management of children with Attention-Deficit Hyperactivity Disorder. As a school-based program, PARD coordinates medical, psychosocial, behavioral, and educational interventions for each child, and provides resources for school personnel caring for children with ADHD. Three years after instituting PARD, about 60% to 70% of the children showed improvement after enrollment, evaluation, and treatment. Parental involvement in and acceptance of intervention for their children represented a significant follow-up problem. Both medical and nonmedical interventions such as counseling, special programs, and behavior modification helped improve the educational life of these children.

Attention Deficit Disorder with Hyperactivity↗
PubMed1993

Can histopathologists reliably diagnose molar pregnancy?

AIMS: To assess the degree of difficulty in diagnosing partial mole by analysing intraobserver and interobserver agreement among a group of pathologists for these diagnoses. METHODS: Fifty mixed cases of partial mole, complete mole, and non-molar pregnancy were submitted to seven histopathologists, two of whom are expert gynaecological pathologists; the other five were district general hospital consultants, one of whom works in Australia. These participants gave each slide a firm diagnosis of either partial mole, complete mole, or non-molar pregnancy. Some 12 months later, the slides were recorded and again submitted for a second diagnostic round to assess intraobserver as well as interobserver agreement. Standard histological criteria for each diagnostic category were circulated with the slides. RESULTS: kappa statistics showed that complete mole could be reliably distinguished from non-molar pregnancy, but neither non-molar pregnancy nor complete mole could be easily differentiated from partial mole. In only 35 out of 50 cases was there agreement between five or more of the seven participants. Agreement between the expert gynaecological pathologists was no better than for others in the group. Interestingly, the intraobserver agreement for each pathologist was good to excellent. CONCLUSIONS: These results imply that the reported histological criteria are either not being applied consistently or that they are lacking in practical use. An atypical growth pattern of trophoblast, rather than the polar accentuation seen in normal first trimester pregnancies, seems to be the important diagnostic histological feature for partial mole. Ploidy studies might also help with problem cases.

Adult↗
PubMed1993

Straight segmental versus bifurcation grafts for repair of abdominal aortic aneurysm.

The decision of two surgical teams to repair an infrarenal aneurysm with a straight or bifurcation graft in 94 patients was investigated. Nine patients had an emergency operation and the two who died within 30 days of surgery (mortality rate 2%) had a ruptured aneurysm. Of 88 patients with follow-up data of at least 1 year (mean 3.5 years), 46 received bifurcation grafts and 42 tube grafts. The mean transverse diameter of the aneurysm on ultrasonography was 6.5 cm for straight and 6.1 cm for bifurcation grafts. The mean duration of operation was longer for bifurcation than straight grafts (4.2 versus 3.3 h, P < 0.05) and intraoperative blood loss greater for the former (2292 versus 1350 ml, P < 0.05). The incidences of late complications for the two grafts were not different. The only secondary aneurysm repair was a staged procedure on a descending thoracic aortic aneurysm. No postoperative iliac aneurysms were detected by routine physical examination and pelvic ultrasonography in patients receiving straight grafts. Even though there was no preselection of patients by disease status, one surgical team relying on preoperative arteriography successfully replaced 28 of 39 aneurysms (72%) with tube grafts while the other team using primarily intraoperative assessment placed straight grafts in only 14 of 49 patients (29%). In conclusion, straight grafts can be implanted in approximately two-thirds of patients undergoing aortic aneurysm repair with significantly less operating time and blood loss and without increase in the incidence of late iliac occlusion or dilatation.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1993

Pediatric liver tumors.

The information in this chapter is a resource for the pathologist faced with a pediatric liver tumor. Each tumor is characterized concisely and appropriate references are provided for more detailed study. Examples of tumors are presented from the files of Children's Hospital-Oakland and from the University of California Medical Center.

Adenoma, Liver Cell↗
PubMed1992

Guidelines for surgical residents' working hours. Intent vs reality.

To comply with voluntary California medical school guidelines, our general surgery residency program reduced in-house call to 1 in 4 nights, and scheduled a 72-hour work-week. We assessed the effectiveness of these changes by prospectively surveying the actual working hours of surgical house staff through completion of a daily schedule for 1 month. Actual in-hospital hours averaged 98 per week, significantly exceeding the scheduled hours, and were greater for interns (100 hours) and junior residents (97 hours) than for chief residents (95 hours). Twenty hours (22%) of nonconference waking hours were spent on so-called scut work. Significant reduction of intern work hours could be accomplished by expansion of ancillary care, allowing more time for direct patient care. The effect on senior house staff hours would be less dramatic but might be sufficient to bring hours into compliance with proposed limits.

General Surgery↗
PubMed1992

The effect of fibrin glue on intraperitoneal contamination in rats treated with systemic antibiotics.

Intraperitoneal fibrin sealant lowers septic mortality in a rat model of peritoneal contamination (2 x 10(6) organism inoculum) at the cost of increased late intraabdominal abscesses. This study utilized parenteral antimicrobials to determine if the protective effect of intraperitoneal fibrin could be achieved without increasing the late abscess formation rate. One hundred and fifty-five rats were divided into four groups. Gelatin capsules containing various dilutions of feces (10(10) CFU/ml) and barium sulfate were placed into the abdomen in all groups. Group I controls had no antibiotics or fibrin. In group II, the capsule was surrounded by a solution of cryoprecipitate, thrombin, and calcium (fibrin "glue"). Groups III (no fibrin, antibiotics) and IV (fibrin, antibiotics) received a broad-spectrum cephalosporin intramuscularly postoperatively and then daily. Surviving rats were sacrificed on the tenth postoperative day. At a moderate volume of fecal inoculum (0.3 ml), fibrin reduced mortality from 100% in the control group to 0% in treated animals (P less than 0.001) that did not receive antibiotics. Abscesses formed in 10% of the surviving fibrin-treated rats which were implanted with 0.1 ml of inoculum. In the 0.2 and 0.3 ml inoculum groups substantially more abscesses occurred (75 and 70%, respectively). The protective effect of fibrin was not manifested in the antibiotic-treated rats since no deaths occurred in either group. At higher and lower inoculum doses, no significant differences between fibrin and control groups were observed in mortality or abscess formation, whether or not antibiotics were given.(ABSTRACT TRUNCATED AT 250 WORDS)

Abscess↗
PubMed1992

Demonstration of sites of latency of infectious laryngotracheitis virus using the polymerase chain reaction.

Mature laying chickens were inoculated intratracheally with a field strain of infectious laryngotracheitis (ILT) virus. Tracheal swabs were collected regularly from all birds for virus culture. At various times post-inoculation, pairs of birds were killed and tissues removed for detection of virus products using conventional tissue homogenization and culture, organ culture, indirect immunofluorescence (IF) and also the polymerase chain reaction (PCR). The latter was used to detect a DNA sequence from the ILT virus thymidine kinase gene. Following inoculation the birds developed mild respiratory disease with clinical signs characteristic of ILT from 3 to 10 days post-inoculation. Trachea and turbinate tissues were virus-positive as determined by virus isolation, organ culture, IF and PCR on day 4 post-inoculation. After recovery from the acute phase, virus shedding initially ceased, then intermittent, low level shedding was recorded for five of the six remaining birds. In an attempt to locate sites of latency, pairs of birds were sampled at 31, 46 and 61 days post-inoculation. Virus was not detected in upper respiratory tract or ocular tissues by conventional techniques, or in the trigeminal, proximal and distal ganglia. All tissues were also negative by PCR, except for the trigeminal ganglia of five of the six birds. All PCR-positive birds had previously shed ILT virus intermittently between days 19 and 59 post-inoculation. As we did not detect viral DNA in any of the other tissues sampled from clinically recovered birds, we conclude that the trigeminal ganglion is the main site of latency of ILT virus.

Animals↗
PubMed1992

Age, site and distribution of subepithelial neurosecretory cells in the appendix.

The appearance of subepithelial neurosecretory cells (SNC) was investigated by studying completely sampled appendices of 50 children, adolescents and adults. The cells were demonstrated using lead hematoxylin, a selective stain for neurosecretory cells. Additional routinely sampled specimens were also studied for comparison. In children up to the age of 9 yrs only occasional SNC were found. After this age, however, SNC were present in most appendices and in greater numbers. The majority of SNC were located in the distal portion of the appendix, with only small numbers of these cells being present in the proximal segment. Occasional SNC-like cells were identified in the appendiceal submucosa in all regions of the appendix at all ages. This lends support to the hypothesis that a correlation exists between the presence of increased numbers of SNC, patient age and the site distribution of both acute appendicitis and appendiceal carcinoid tumors.

Adolescent↗