Biomedical subjects

A Montgomery

Publications and source records attributed to A Montgomery.

At least 19 recordsLinked to original sources

PubMed1992

The time course of thyroid-hormone-induced changes in the isotonic and isometric properties of rat soleus muscle.

Rat thyroidectomy resulted in changes in a number of parameters used to characterise the mechanical and histochemical status of skeletal muscle. Thus thyroidectomy resulted in a prolongation of soleus slow-twitch muscle isometric contraction time and half-relaxation time with a reduced maximum velocity of shortening and maximum rate of development of tetanic tension but no significant change in twitch: tetanus ratio i.e. the ratio of twitch force/unit area to tetanic force/unit area. In addition the percentage of IIA fibres was reduced and the percentage of type I fibres increased. Triiodothyronine, administered to hypothyroid rats, brought about a speeding of these parameters again with no change in twitch: tetanus ratio. There was an increase in the percentage of IIA fibres with a concomitant reduction in the percentage of type I fibres. These changes were induced over 18 days and resulted in isotonic and isometric properties almost identical to those of soleus muscles from chronically hyperthyroid rats; speeding could be detected as early as 2 days after triiodothyronine had been given. Consideration is given to the possibility that changes in myosin isoforms and/or the kinetics of changes in intracellular calcium concentration in activation and relaxation could account for the time course of the observed changes.

Animals↗

PubMed1992

Pancreatic proteases and intestinal mucosal injury after ischemia and reperfusion in the pig.

Intraluminal pancreatic proteases have been proposed to play a pathogenic role in the injury seen after ischemia and reperfusion of the small intestinal mucosa. Intestinal ischemia can be detected by indirect intramucosal pH measurements using tonometry. In this study, pigs were subjected to laparotomy and ligation of the pancreatic duct (n = 10) or a sham procedure (n = 10). Three weeks later, a standardized hemorrhagic shock was induced followed by retransfusion. Central hemodynamics, portal venous flow, and duodenal and small intestinal mucosal intramucosal pH were monitored. Samples were obtained from the small intestine for microscopic examination. A typical superficial mucosal injury developed in both groups of animals after reperfusion. However, the injury developed significantly later in the duct-ligated animals. No major differences in survival, splanchnic hemodynamics, or intramucosal pH between the groups were seen during hemorrhagic hypotension or after reperfusion. These data favor the concept that intraluminal pancreatic proteases are important for the rapid development of the mucosal reperfusion injury.

Animals↗

PubMed1992

Protease activation following reperfusion of porcine pancreatic allografts.

To study the degree of protease activation at reperfusion of a pancreatic allograft after cold storage for 24 hr, 18 porcine whole-organ pancreaticoduodenal allograft transplantations were performed. Twelve grafts were flushed with and stored in Perfadex. In six of these, a hyperosmotic salt solution was injected into the graft aorta at reperfusion. Six grafts were flushed and stored in UW solution. Eleven of twelve grafts in the Perfadex groups were functioning on the first postoperative day, compared with one of six in the UW solution group. There was a significantly more pronounced protease activation among grafts stored in UW solution than in the other groups, with a subsequent breakthrough of the local protease protection barrier made up of protease inhibitors. In surviving pigs (n = 14), biochemical signs of protease activation evolved in plasma, including formation of trypsin-protease inhibitor complexes, a decline in C3 and kininogen levels, and a decline in functionally active alpha 2-macroglobulin, functionally active antithrombin III, and plasma kallikrein inhibitory activity. These biochemical signs of pancreatitis correlated with a deteriorated graft function on the second postoperative day, indicating that graft tissue damage occurred due to protease activation.

Animals↗

PubMed1992

Duodenal mucosal pH as a reperfusion indicator in pancreatic-duodenal transplantation in the pig.

We have studied differences in reperfusion between the pancreas and the duodenum after 6 hr of cold storage in a porcine whole-organ pancreaticoduodenal allograft transplantation model. Two different flush-out and storage solutions, Perfadex and EuroCollins, were compared. Graft duodenal mucosal pH (pHi) was measured as an indicator of duodenal mucosal reperfusion. Pancreatic reperfusion was estimated indirectly using a ratio between the release of immunoreactive cationic trypsin (irCT) to serum 10 and 60 min following reperfusion. Twelve pigs (Perfadex n = 6, EuroCollins n = 6) were transplanted and all showed preserved endocrine and exocrine function postoperatively. Our data support the concept that reperfusion of a pancreaticoduodenal graft can be estimated using duodenal pHi and that the ratio of irCT at 10 and 60 min gives an indirect estimate of pancreatic reperfusion. The results also show that grafts stored in EuroCollins reperfuse more slowly than grafts stored in Perfadex.

Animals↗

PubMed1992

Laparoscopic cholecystectomy in a patient with hemophilia B.

Surgical procedures in hemophiliacs is a demanding challenge for the surgeon and hematologist. This report deals with a successful laparoscopic cholecystectomy in a young patient with hemophilia B. Despite a prolonged operation time, because of a partially intrahepatic gallbladder, no bleeding complications were registered and the patient recovered well. Laparoscopic cholecystectomy seems to be the method of choice in hemophiliacs, as it minimizes tissue trauma. Nevertheless, the procedure should be performed only in specialized centers with a fully equipped coagulation laboratory and a team of surgeons and hematologists familiar with the special problems of surgery in hemophiliacs.

Adult↗

PubMed1991

Allelic association of the D2 dopamine receptor gene with receptor-binding characteristics in alcoholism.

The allelic association of the human D2 dopamine receptor gene with the binding characteristics of the D2 dopamine receptor was determined in 66 brains of alcoholic and non-alcoholic subjects. In a blinded experiment, DNA from the cerebral cortex was treated with the restriction endonuclease Taql and probed with a 1.5-kilobase (kb) digest of a clone (lambda hD2G1) of the human D2 dopamine receptor gene. The binding characteristics (Kd [binding affinity] and Bmax [number of binding sites]) of the D2 dopamine receptor were determined in the caudate nuclei of these brains using tritiated spiperone as the ligand. The adjusted Kd was significantly lower in alcoholic than in nonalcoholic subjects. In subjects with the A1 allele, in whom a high association with alcoholism was found, the Bmax was significantly reduced compared with the Bmax of subjects with the A2 allele. Moreover, a progressively reduced Bmax was found in subjects with A2/A2, A1/A2, and A1/A1 alleles, with subjects with A2/A2 having the highest mean values, and subjects with A1/A1, the lowest. The polymorphic pattern of the D2 dopamine receptor gene and its differential expression of receptors suggests the involvement of the dopaminergic system in conferring susceptibility to at least one subtype of severe alcoholism.

Alcoholism↗

PubMed1991

The impact of elder health, caregiver involvement, and global stress on two dimensions of caregiver burden.

This study examined the simultaneous effects of an elder's health, caregiver involvement, and stress on caregiver burden, addressing the questions: (a) What are the direct and indirect effects of level of elder's impairment, caregiver involvement, and stress on personal and interpersonal burden? (b) How do these relationships differ between spouse and adult-child caregivers? Data were from the 1982 National Long Term Care Survey. Results using linear structural relations analysis showed the effect of a frail elder's health and functioning on personal and interpersonal burden is mediated by task involvement and perceived global stress. Contrary to expectation, there were few differences in the direct effect of each dimension of health, functional limitations, cognitive status, and global health rating on each dimension of burden. Although the results suggested mean differences between spouse and adult child caregivers on key variables, there were no differences by family relationship in the system of relationships that comprise the process linking health and burden.

Activities of Daily Living↗

PubMed1991

Tissue oxygenation in hemorrhagic shock measured as transcutaneous oxygen tension, subcutaneous oxygen tension, and gastrointestinal intramucosal pH in pigs.

BACKGROUND AND METHODS: Tissue oxygenation, measured in peripheral tissue as transcutaneous PO2 (PtCO2) and subcutaneous PO2, was compared with the oxygenation in GI mucosa, which was measured as intramucosal wall pH (pHi), during experimental hemorrhagic shock and resuscitation in pigs. The pigs were hemorrhaged stepwise to a BP of 80 and 45 mm Hg, followed by retransfusion. PtCO2 was measured in the groin and subcutaneous PO2 was measured in the hip region. Intraluminal PCO2 was measured in the stomach, in the small intestine, and the sigmoid colon using silicone catheters. A simultaneous determination of arterial blood HCO3 concentration allowed pHi to be calculated using Henderson-Hasselbalch equation. Cardiac output was determined by thermodilution, and oxygen delivery (DO2) was calculated. RESULTS: Early indications of shock were decreases in PtCO2 and intestinal pHi (p less than .01). All measured variables decreased at the second step of bleeding. PtCO2 and subcutaneous PO2 was correlated to DO2 through the entire experiment (r2 = .25 and .49, respectively). Also, the pHi of the small intestine and the sigmoid colon correlated with DO2 (r2 = .36 and .25, respectively). PtCO2 and subcutaneous PO2 correlated with pHi in the small intestine and sigmoid colon. CONCLUSIONS: PtCO2 and pHi in the small intestine and sigmoid colon were the variables that most rapidly indicated blood volume loss. Subcutaneous PO2 and PtCO2, and small intestine and sigmoid colon pHi were correlated to total body oxygen transport. Peripheral tissue perfusion followed intestinal perfusion to some extent.

Animals↗

PubMed1991

Care of the elderly in north and west Belfast.

A survey of all elderly people aged 65 years and over from North and West Belfast receiving long-term care in residential and nursing homes, and in psycho-geriatric and geriatric care was undertaken. A total of 967 subjects was studied and physical dependency and mental impairment documented. The high dependency of residents in geriatric and psycho-geriatric care was highlighted, with greater levels of dependency than among those receiving nursing home care. Professional assessment prior to admission should be common to all long-term care facilities and is essential if services for the projected demographic increase in numbers of very elderly people are to be provided, and inappropriate admission and expenditure avoided.

Aged↗

PubMed1990

Allelic association of human dopamine D2 receptor gene in alcoholism.

In a blinded experiment, we report the first allelic association of the dopamine D2 receptor gene in alcoholism. From 70 brain samples of alcoholics and nonalcoholics, DNA was digested with restriction endonucleases and probed with a clone that contained the entire 3' coding exon, the polyadenylation signal, and approximately 16.4 kilobases of noncoding 3' sequence of the human dopamine D2 receptor gene (lambda hD2G1). In the present samples, the presence of A1 allele of the dopamine D2 receptor gene correctly classified 77% of alcoholics, and its absence classified 72% of nonalcoholics. The polymorphic pattern of this receptor gene suggests that a gene that confers susceptibility to at least one form of alcoholism is located on the q22-q23 region of chromosome 11.

Alcoholism↗

PubMed1990

Family caregivers and limitations in social activities.

Constriction of social and personal activities is one of the most frequently noted consequences of caring for a frail elder. This study analyzed the correlates of perceived limitations in social activities using data from a national sample of the frail elderly and their caregivers. Two research issues were addressed: 1) What differences in demographic, family, and caregiving attributes are associated with variation in perceived restricted social activities? and, 2) How does the process influencing restriction of social activities vary by family relationship of the caregiver? Higher levels of elder dependency and task demands were characteristic of those who reported social limitations, and daughters and wives were more likely to report such limitations than sons and husbands. Subjective assessment of time and task demands, however, were more important influences than objective caregiving activities for all family caregivers.

Aged↗

PubMed1990

Lack of beneficial effects of milrinone in severe septic shock.

The effects of milrinone were investigated in a porcine septic shock model. Septic shock was induced by i.v. infusion of live Escherichia coli. Anesthetized pigs were treated with milrinone before the E. coli infusion or were left untreated as septic controls. E. coli caused a significant reduction of cardiac index, renal blood flow, and portal blood flow. Pulmonary vascular resistance was significantly increased, as were the systemic and preportal vascular resistances. One of the seven septic control pigs died. In milrinone-treated septic animals cardiac index was maintained for a longer period of time but blood pressure was significantly reduced compared with the control pigs. Pulmonary vasoconstriction was little affected by pre-treatment with milrinone. Four out of seven milrinone-treated pigs died during the observation period. It is concluded that in the settings of the used porcine septic shock model milrinone treatment has no beneficial effect.

Animals↗

PubMed1990

Community health advocacy: primary health care nurse-advocate teams in urban communities.

In summary, our health advocacy program uses PHC teams in urban, underserved communities to deal with the interaction of social and health factors in solving problems related to access to appropriate (as perceived by residents) and affordable health care. This approach encourages grass-roots participation in problem identification and solution, a fundamental ingredient of community empowerment. Further, this program facilitates community identification of nurses as resource persons who encourage collaboration to improve the community's health status and as health providers who enhance the authority and autonomy of community participation in the resolution of health issues.

Community Health Nursing↗

PubMed1990

Early detection of gastrointestinal mucosal ischemia in porcine E. coli sepsis.

The aim of this study was to investigate the oxygenation of the gastrointestinal tract mucosa using indirect pH measurements in a porcine septic model (intravenous infusion of live E. coli). By means of intraluminally placed balloon catheters (Tonomitior) permeable to CO2, intramucosal pH (pHi) was calculated using the Henderson-Hasselbalch equation. Cardiopulmonary hemodynamics and portal blood flow were measured using Swan-Ganz catheters. Samples were taken from the gastrointestinal tract for histological examination. Nine pigs were given i.v. E. coli infusion while six pigs served as sham controls and were given an equivalent amount of Ringer's solution only. All septic animals developed hemodynamic signs of septic shock. Gastric, small intestinal and sigmoid colonic pHi decreased gradually during the four hour observation period. In the small intestine and the sigmoid colon the decrease was significant already after one hour (p less than 0.01 and p less than 0.02, respectively). Microscopic examination of tissue specimens obtained 4 hours following induction of sepsis revealed normal or close to normal findings in all the sham and in more than half of the septic animals. These findings indicate that abnormally low gastrointestinal intramucosal pH may be found early in septicemia, preceding microscopically detectable damage by several hours. It is concluded that the tonometer technique does provide early detection of gastrointestinal ischemia in septic shock.

Animals↗

PubMed1989

Heterogeneity within an HSV-1 wild-type strain and its importance in pathogenesis.

A herpes simplex virus-type 1 low passage, clinical eye isolate, E-43 at P2, was compared with its variant progeny, SLi-43 at P8, in terms of ocular disease, cytopathic effects, and genomic variation. In New Zealand White (NZW) rabbits, E-43 produced mild epithelial defects and punctate lesions with full recovery by Day 10 postinfection (pi). SLi-43 caused dendritic lesions, progressing to geographic ulceration and death from herpes simplex virus encephalitis in 10 days postinfection. In RK, Hep-2, and Vero cells, E-43 displayed the syn+ phenotype (aggregation and cell rounding); SLi-43 showed the syn phenotype (syncytium formation). DNA digestion profiles of E-43, SLi-43, and isolates from the brains of infected animals showed that the genomic differences map within the terminal repeat of the unique long segment and the internal joint region, specifically in bands B, E, N, and S (Bam HI) and bands M and N (Hind III). Analysis of the DNA of virus recovered from the brain stem of SLi-43-infected, encephalitic rabbits demonstrated that an in vivo selection for neurotropic virions had taken place. Plaque purification of 20 clones from the original E-43 strain showed that one of 20 was the syn phenotype, indicating that the SLi-43 variant was present in the original E-43 isolate and did not develop de novo by rapid mutation. The parent-progeny relationship between E-43 and SLi-43 forms an ideal model in which to compare differences in pathogenicity at the genomic level, and underscores the importance of heterogeneity within a single herpes simplex virus-type 1 wild-type population in terms of variations in ocular disease.

Animals↗

PubMed1989

Intramucosal pH measurement with tonometers for detecting gastrointestinal ischemia in porcine hemorrhagic shock.

Intraluminal pCO/ was measured in the stomach, small intestine, and sigmoid colon of pigs using balloon catheters (Tonomitor). With the simultaneously determined arterial blood HCO3 concentration, the intramucosal pH (pHi) could be calculated using the Henderson-Hasselbalch equation. Cardiac output and portal venous flow were measured using Swan-Ganz catheters. A series of 35 normotensive pigs were studied to achieve normal values of cardiac output, gastrointestinal pHi, and blood flow in pigs. In another series of pigs (n = 12), hemorrhage was induced in two steps and followed by retransfusion. Five additional animals served as controls. Gastric, small intestinal, and colonic pHi decreased with increasing degree of hemorrhage but remained unchanged in the controls. Following severe hemorrhage, pHi fell below the normal range in all pigs but one. It recovered only partly following retransfusion. Histological examination of specimens obtained following retransfusion revealed normal mucosa in six of eight investigated animals and superficial mucosal injury in the remainder, indicating that abnormal pHi may be found for a period in the microscopically normal gastro-intestinal mucosa. Monitoring pHi in the stomach, small intestine, or colon using tonometers could be a useful technique to reveal insufficient mucosal blood flow in the alimentary canal.

Animals↗

PubMed1988

Water, electrolyte, glucose, and glycine absorption in rat small intestinal transplants.

Water, electrolyte, glucose, and glycine absorption were studied in vivo in successful rat small intestinal transplants. Isolated bowel loops were transplanted from F1 hybrids into parental strain Lewis rats. A 7-day course of cyclosporin A was given for immunosuppression. Absorption was studied using a steady-state perfusion technique at either 9 or 21 days after transplantation. Histologic examination showed there was villus shortening with time but no evidence of rejection. When perfused with isotonic saline, both allografts and controls secreted water. However, allografts and denervated controls secreted chloride, whereas innervated controls absorbed chloride (p less than 0.05). There was a marked reduction in water and sodium absorption from 30 mM glucose-saline in transplanted loops and denervated controls, whereas glucose absorption was relatively preserved in these groups at 9 days (p less than 0.01). These changes could not be accounted for by rejection or ischemia. These studies demonstrate that denervation may be a major limiting factor in intestinal transplantation.

Animals↗

PubMed1988

Technique for physiological examination of canine skeletal muscle in vivo.

A technique is described for studying the physiological function of canine skeletal muscle in vivo. The contractile properties of the tarsal flexor muscles were examined in three beagle dogs under general anaesthesia. The force responses to electrical stimulation of the common peroneal nerve were measured at various frequencies to determine the frequency:force relationship for this muscle group. Fatigue characteristics were also examined during intermittent stimulated activity delivered in a set pattern of frequencies. The results provide quantitative characterisation of muscle function which is repeatable. The technique described could be applied to other animals and is a potentially powerful tool for evaluating the effects of drugs on muscle performance.

Animals↗