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Biomedical subjects

A R Williams

Publications and source records attributed to A R Williams.

At least 145 records · Page 8Linked to original sources
PubMed1986

Pepsinogens in gastric carcinomas.

Polyclonal rabbit antisera raised against the two major groups of human pepsinogens (PG I and PG II) were used in an immunohistochemical study of human gastric carcinomas. Thirty-two carcinomas, classified histologically according to the Lauren classification as diffuse or intestinal, were studied; and the staining patterns of the tumor and adjacent gastric mucosa were assessed. In some of the tumors of both types, PG I and/or PG II staining of the neoplastic cells was seen, with PG I being found significantly more frequently than PG II. No characteristic staining pattern was associated with either Lauren type. (The presence of pepsinogens in gastric carcinoma cells therefore appears unlikely to be of relevance to the Lauren type of the tumor.) These findings do not support the notion of a separate histogenesis for diffuse and intestinal types of gastric carcinoma.

Carcinoma↗
PubMed1986

Evaluation of a monoclonal antibody to ras peptide, RAP-5, claimed to bind preferentially to cells of infiltrating carcinomas.

RAP-5, a monoclonal antibody raised against a p21ras peptide, has been claimed to show immunohistochemical localisation of cells with infiltrative properties in human tumours. We confirmed that this antibody reveals pronounced cellular heterogeneity in human colonic neoplasms but could find no obvious relationship to infiltrative activity. RAP-5 bound to many different cell types, neoplastic and normal. In order to clarify the specificities of RAP-5 we applied it to two cell lines: nontumorigenic hamster fibroblasts in which ras expression is barely detectable, and a vigorously tumorigenic line derived from these fibroblasts by insertion of the human mutated Ha-ras oncogene in a high expression vector. Another antibody to p21ras, Y13-259, clearly distinguished between these cell lines both on immunoblots and immunocytochemically, but RAP-5 did not. Rather, it bound to proteins of a variety of molecular weights in both cell lines. The results show that RAP-5 is unlikely to be a useful reagent for detection of ras associated proteins in human tissues.

Adenocarcinoma↗
PubMed1986

Selective oxygen leak. A potential cause of patient hypoxia.

A case is described where a patient received less oxygen than was set on the Rotameters. The cause was traced to a selective leak of oxygen via an open cyclopropane needle valve. Several recommendations are put forward to prevent a recurrence.

Anesthesia, Inhalation↗
PubMed1986

Thermal and heart rate response to ultrasonic exposure in the second and third trimester dog fetus.

A total of 39 fetuses from five pregnant dogs were used in this study. Following pentobarbital anesthesia of the dams the gravid uterus was exposed and partially exteriorized. Fetal and maternal electrocardiograms were recorded, along with fetal abdominal temperatures, during ultrasound exposures of 3.4 MHz and 2, 4, 6, 8 or 12 W/cm2 (continuous wave), spatial average intensities, for 6 minutes. Baseline fetal abdominal temperatures were 35.2 +/- 1.5 (SD) degrees C. Baseline fetal heart rates were 176.8 +/- 4.3 (SD) beats per minute. These studies indicate that the product of intensity and time of exposure, under the conditions of these experiments, is directly related to increases in fetal abdominal temperature and fetal heart rate.

Animals↗
PubMed1986

Gastric emptying of liquids in the dog: effect of volume.

Effect of liquid test meal volume on gastric emptying was investigated in healthy nonoperated dogs fed meal sizes of 6.6 to 110 ml/kg of body weight. For meals less than or equal to 66 ml/kg, the amount of test meal emptied from the stomach in 30 minutes vs meal size could be described as following a linear, exponential, or square root pattern. Deviation from these patterns was seen with test meals of 77, 88, and 110 ml/kg. A mean +/- SEM maximum of 0.99 +/- 0.06 ml/kg/min of liquid test meal was emptied from the stomach of dogs fed test meals of 77, 88, and 110 ml/kg. Massive gastric distension induced in dogs during this study did not alter gastric emptying of the liquid test meal.

Animals↗
PubMed1985

Computer simulations and the use of radiolabelled sulphur colloid to measure the efficiency of the mononuclear phagocyte system.

Techniques are described whereby the clearance of the radiolabelled blood borne colloid can be continuously and reproducibly measured non-invasively from the same animal in vivo or from the isolated perfused intact liver in vitro. Using these techniques, the rate of removal of radiolabelled sulphur colloid by the mononuclear phagocytes in vivo and in vitro was shown to be biexponential. The pattern of clearance of colloid and the factors contributing to this were analysed with the aid of a computer program which mimicked the in vitro liver perfusion.

Animals↗
PubMed1985

Interaction of therapeutic ultrasound with purified enzymes in vitro.

The effects of ultrasound on the rates of the catalytic reactions of four purified enzymes in vitro have been extensively investigated under a wide range of biochemical and physical exposure conditions. In general, it can be concluded that therapeutic intensities of continuous wave 0.88 MHz ultrasound had no detectable direct effects on the rates of the reactions catalysed by creatine kinase, lactate dehydrogenase, hexokinase and pyruvate kinase. Some minor effects were noted. These were: an indirect effect resulting from mixing within the sample chamber caused by quartz wind streaming; an effect on partially-hydrated cross-linked enzyme systems which appears to be the result of increased fluid penetration of the solid matrix in the presence of ultrasound; and an increase in the rate of spontaneous dissociation of a multimeric enzyme system. It is, therefore, concluded that a direct interaction between ultrasound and the catalytic functioning of individual enzyme molecules is unlikely to be the primary step in any acousto-biological interaction, and that this primary interaction appears to be occurring at a higher level of organizational complexity.

Catalysis↗
PubMed1985

Altered emotionality of the vasopressin-deficient Brattleboro rat.

Observation of open field behavior of vasopressin-deficient (DI) and normal Long-Evans rats indicated elevated levels of open field activity for the DI rats. Exposure to an acoustic stressor resulted in decreased activity in both groups of animals but with a lesser effect on the DI rat. Handling prior to experimentation diminished the differences between DI and normal rats. Although both groups displayed an equivalent rise in plasma corticosterone in response to the open field, the addition of the acoustic stressor resulted in greater elevation of corticosterone in the normal animals. The behavioral and hormonal data suggest that the DI rat exhibits decreased emotional reactivity. Measurement of brain neurotransmitter levels revealed higher concentrations of serotonin, norepinephrine and dopamine in the limbic regions of the DI rat. These alterations may underlie the behavior reflecting decreased emotionality of the DI rat. In turn, the altered emotional state may be the basis for alteration in performance on learning/memory tasks of these animals. Thus, vasopressin effects on the retrieval and/or consolidation of information may not be direct but rather through its ability to influence the emotional state of the animal.

Acoustic Stimulation↗
PubMed1985

Immunohistochemical detection of the ras oncogene p21 product in an experimental tumour and in human colorectal neoplasms.

The monoclonal antibody Y13 259 to the ras oncogene protein product p21 was used in an immunohistochemical study of ras expression in human colorectal neoplasms. The ability of the antibody to detect enhanced levels of ras expression was confirmed by its use with an experimental neoplasm known to express ras at high levels. Human colonic adenocarcinomas in general showed a similar staining intensity to that seen in normal mucosa. Adenomas however showed consistently high p21 expression as indicated by staining intensity. This suggests that elevated ras expression may be important in the development of adenomas, but that high levels need not be sustained in the conversion to invasive carcinoma.

Adenocarcinoma↗
PubMed1985

Carcinoid tumour of the ampulla of Vater.

A 60 year old female with a carcinoid tumour of the ampulla of Vater is presented. The importance of considering this diagnosis in localized lesions of common bile duct or ampulla of Vater and thus avoiding more radical surgery is stressed.

Ampulla of Vater↗
PubMed1985

Gastric emptying of liquids in the dog: serial test meal and modified emptying-time techniques.

A serial test meal technique was used in the dog to evaluate the gastric emptying of a liquid test meal. On separate days, a phenol red test meal was placed in the stomach and completely aspirated at different times. A composite representation of the gastric emptying pattern was obtained for each dog, and a set of normative data was generated. Three emptying determinants (emptying time, half-life, and starting index) were calculated. The basic pattern of canine gastric emptying was linear and declined exponentially or as a function of the square root of the gastric volume. A modified emptying-time technique (METT) correlated well with the serial test meal and a set of normative values was determined. The METT was performed by aspirating test meal from the stomach 30 minutes after instillation. The METT was a simple and inexpensive technique that could be performed in 1 short testing period. With the METT, the half-life of gastric emptying was calculated, using the log of the percentage of retention of test meal; gastric emptying time was calculated, using the square root of the percentage of retention of test meal. Acetylpromazine was shown not to alter gastric emptying of a liquid test meal.

Animal Feed↗
PubMed1985

Gastric distention and gastrin in the dog.

Gastric distention was induced in intact dogs by giving a wide range of volumes (11 to 111 ml/kg) of a liquid test meal resulting in a significant (P less than 0.05) increase in plasma gastrin immunoreactivity at 10 and 25 minutes after distention. There was no significant decrease in gastrin immunoreactivity from 10 to 25 minutes of gastric distention. Pretreatment with atropine abolished the distention-induced gastrin release, indicating that distention-induced gastrin release in the intact dog was partially under cholinergic control. There was no relationship between the distending volume and magnitude of gastrin increase.

Acepromazine↗