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Biomedical subjects

R Graham

Publications and source records attributed to R Graham.

At least 55 records · Page 3Linked to original sources
PubMed1987

Acquisition of endemic Pseudomonas aeruginosa on an intensive therapy unit.

During a 9-month period, patients, staff and environment were monitored in order to trace the source of endemic Pseudomonas aeruginosa on our intensive therapy unit (ITU). Of 81 patients studied, 14 (17%) acquired 15 different pyocin types while on the ITU. The most frequent site of colonization was the rectum (11 patients). Rectal strains subsequently appeared in urine (two patients), wound (one) and sputum (four) of six patients. Three episodes of cross-infection (wound (two), urine (one] occurred without development of rectal colonization. Strains isolated from the environment and staff were not implicated. While gastrointestinal carriage of P. aeruginosa may not be detected on admission to the ITU, excessive use of antibiotics may be responsible for apparent acquisition of the organism followed by endogenous transfer of the rectal strains to other sites of the body.

Cross Infection↗
PubMed1987

Effects of norepinephrine and fluid administration on diaphragmatic O2 consumption in septic shock.

The effects of norepinephrine infusion and fluid administration on diaphragmatic O2 consumption during endotoxic shock were assessed in spontaneously breathing anesthetized dogs. Blood flow was measured with the microsphere technique, and diaphragmatic venous blood was obtained via a catheter inserted into the left inferior phrenic vein. One group of dogs (n = 6) received 10 mg/kg Escherichia coli endotoxin intravenously (E group). In the second and third groups, blood pressure after endotoxin injection was restored by continuous infusion of norepinephrine tartrate (N group) or by infusion of normal saline and dextran infusion (F group). The animals were observed for 2 h after endotoxin injection. Cardiac output fell significantly in the E and N group, whereas it was restored in the F group. Minute ventilation and diaphragmatic pressure-time index rose twofold in the three groups of dogs. Diaphragmatic O2 consumption (VO2 di) increased substantially in the E group to a mean value of 3.46 ml X 100 g-1 X min-1, which was achieved by higher blood flow and by an increase in O2 extraction. In the N group, VO2 di was higher than control but was lower than that of the E group (mean value of 1.43 ml X 100 g-1 X min-1), which was achieved solely by increasing O2 extraction. In the F group, VO2 di was also lower than that of the E group (mean value of 1.51 ml X 100 g-1 X min-1), which was achieved by high diaphragmatic blood flow. Thus, at any given diaphragmatic task, the diaphragm consumed less O2 in the N and F group than in the E group.

Animals↗
PubMed1987

Zone 2 and zone 3 pulmonary blood flow.

In the West model of zonal distribution of pulmonary blood flow, increases in flow down zone 2 are attributed to an increase in driving pressure and a decrease in resistance resulting from recruitment and distension. The increase in flow down zone 3 is attributed to a decrease in resistance only. Recent studies indicate that, besides the pressure required to maintain flow through a vessel, there is an added pressure cost that must be overcome in order to initiate flow. These additional pressure costs are designated critical pressures (Pcrit). Because Pcrit exceed alveolar pressure, the distinction between zones in the West model becomes less secure, and the explanation for the increase in flow even in West zone 3 requires reexamination. We used two methods to test the hypothesis that the Pcrit is the pertinent backpressure to flow even in zone 3, when the pulmonary venous pressure (Ppv) exceeds alveolar pressure (PA) but is less than Pcrit in the isolated canine left caudal lobe. First, PA was maintained at 5 cmH2O, and pressure flow (P-Q) characteristics were obtained in zone 2 and zone 3. Next, with PA still at 5 cmH2O, we maintained a constant flow and measured the change in pulmonary arterial pressure as Ppv was varied. Both techniques indicated that the pertinent backpressure to flow was the greater of either Pcrit or Ppv and that PA was never the pertinent backpressure to flow. Also, our results indicate no significant change in the geometry of the flow channels between zone 2 and zone 3. These findings refine the zonal model of the pulmonary circulation.

Animals↗
PubMed1987

Mucosal IgA production and lymph cell traffic following prolonged low level infections of Ostertagia circumcincta in sheep.

Some aspects of the local immune response to daily challenge with 2000 Ostertagia circumcincta larvae were studied by monitoring changes in the composition of gastric lymph of naive and previously infected sheep. The main changes in the naive group were increases in lymphoblast output and concentrations of pepsinogen whereas lymph albumin values decreased markedly and IgA concentrations were usually unchanged. In contrast, in the previously infected sheep, the continuous challenge stimulated only transient increases in lymphoblast and IgA containing cell traffic whereas lymph IgA and pepsinogen concentrations remained elevated throughout the experiment. By temporarily interrupting the challenge in a second group of previously infected sheep it was shown that elevated IgA and pepsinogen values were maintained only if larval intake was continuous.

Abomasum↗
PubMed1986

Changes in plasma osteocalcin concentration following treatment with stanozolol.

Treatment of healthy, adult, human volunteers with stanozolol, 5 mg twice daily, for six weeks caused a marked elevation in circulating levels of osteocalcin. Plasma osteocalcin concentrations did not fall to pretreatment values for a period in excess of four weeks after the cessation of treatment but remained similar to levels whilst on treatment. At the same time, as the rise in plasma osteocalcin was seen, plasma alkaline phosphatase activity fell; however, in this case, a return to pretreatment levels occurred within four weeks of treatment ending. These data demonstrate that stanozolol has a detectable effect on the plasma concentration of a protein thought to be a marker of osteoblast activity, and that this effect continues for a period after treatment has been discontinued.

Adult↗
PubMed1986

The effects of ischemia, lactic acid and hypertonic sodium chloride on phrenic afferent discharge during spontaneous diaphragmatic contraction.

In 9 sodium pentobarbital anaesthetized cats, 50 single-unit phrenic afferent recordings were determined during spontaneous ventilation, retrograde carotid arterial injection of lactic acid (LA, 0.1 N) and NaCl (5%), and a 2-min occlusion of the superior thoracic aorta. Fifty percent of the units had tonic low-frequency spontaneous discharge; 50% had phasic high-frequency discharge. Tonic fiber activity increased significantly with LA, NaCl and occlusion, while phasic fiber activity decreased in all 3 conditions. These results suggest that the diaphragm contains sensory endings sensitive to ischemia and extracellular metabolic changes.

Animals↗
PubMed1986

The 24 hours before hospitalization: factors related to suicide attempting.

Fifty-nine psychiatric inpatients were interviewed concerning the psychological and environmental events that occurred in the 24 hours prior to their hospitalization. Independent raters then performed a content evaluation of these accounts, allowing for comparisons among patients admitted for a suicide attempt, suicide ideation, or non-suicide-related complaints. Results showed that suicide attempters were more likely to have used alcohol or marijuana and less likely to have contacted a health care professional than suicide ideators, even when past history of suicide behavior was controlled for. Suicide ideators were more likely to have contacted a mental health professional. Implications for suicide risk assessment and intervention are discussed.

Adult↗
PubMed1986

Respiratory muscle energetics during endotoxic shock in dogs.

Respiratory muscle O2 consumption, lactate production, and endogenous substrate utilization during endotoxic shock were assessed in two groups of anesthetized spontaneously breathing dogs. In the endotoxin group (Escherichia coli endotoxin 10 mg/kg iv) and the sham group (saline iv), we sampled diaphragm, external intercostal, and gastrocnemius muscle tissue for glycogen and lactate concentrations before and after 3 h of the experimental period. Only in the endotoxin group did blood pressure and cardiac output decline significantly. Arterial O2 content did not change significantly during shock, whereas mixed venous, phrenic venous, and femoral venous O2 contents dropped to 8.0 +/- 1.1, 5.8 +/- 0.8, and 3.6 +/- 0.6 ml/dl at 60 min of shock, respectively, with little change thereafter. At 30 min of shock, femoral venous lactate rose higher than arterial values, whereas at 90 min of shock, onward, phrenic venous lactate was significantly higher than arterial concentrations. All muscle tissues showed significant lactate production and glycogen depletion after shock. In a second set of experiments we measured respiratory muscle blood flow during shock with radioactive microspheres. At 60 min of shock, diaphragmatic and intercostal blood flow rose by six- and twofold, respectively, whereas gastrocnemius blood flow declined significantly. We conclude that during endotoxin shock 1) the increased demands of the respiratory muscles are met by increasing blood flow and O2 extraction; 2) anaerobic metabolism and respiratory muscle substrate depletion, or both, may contribute to the observed fatigue.

Animals↗
PubMed1986

Transfer of immunity to Ostertagia circumcincta and IgA memory between identical sheep by lymphocytes collected from gastric lymph.

Sheep rendered immune to Ostertagia circumcincta were challenged with 50,000 larvae and lymphocytes were collected from the gastric lymph up to eight days after challenge. The cells were transferred intravenously to genetically identical worm-free sheep which, together with controls, were challenged with 50,000 larvae and killed nine days later. Cells obtained during the donors lymphoblast response to challenge transferred partial immunity, measured either as stunting or loss of worms. Significantly less immunity was transferred by cells collected either before or after this response. Thus the responding cells can mediate protective immunity to O circumcincta. On the other hand the donor sheep remained immune to their challenge infection despite being depleted of these functional cells, showing that their presence was not essential for immunity to be maintained. Comparison of the immunoglobulin A (IgA) concentrations in the gastric lymph of recipient and control sheep showed that a local IgA response had also been transferred. Enumeration of mucosal mast cells suggested that a mastocytosis had been transferred to the two recipients which were most immune to challenge.

Animals↗
PubMed1985

Torre-Muir syndrome. An association with isolated sebaceous carcinoma.

Three cases of Torre-Muir syndrome are described in which isolated sebaceous carcinomas were associated with internal malignancy. The first was a 66-year-old woman who had a sebaceous carcinoma in association with carcinoma of the uterus, two adenocarcinomas of colon, carcinoma of renal pelvis and bladder, and a squamous cell carcinoma of the skin. The second was a 78-year-old woman who had a sebaceous carcinoma associated with carcinomas of the colon, ovary, and pancreas. The third patient had a sebaceous carcinoma associated with breast cancer. The subject is discussed and the previously reported cases reviewed.

Abdominal Muscles↗
PubMed1985

Dental occlusal wear and degenerative disease of the temporomandibular joint: a correlational study utilizing skeletal material from a contemporary population.

Forty crania and mandibles with intact dentition exceeding twenty-six teeth and bilaterally intact condyle-fossa apparatus were evaluated for attrition and degenerative joint disease. The skeletal specimens all represent a twentieth-century contemporary American population from the Atkinson Skull Collection at the University of the Pacific School of Dentistry. While 23.1% of this sample exhibited some degree of erosive osseous degenerative wear involving the condyle or articular fossa and 76.3% exhibited occlusal tooth wear, no significant correlation between the degree of attrition and the severity of degenerative joint disease could be documented.

Adult↗
PubMed1984

Effect of hypoxic hypoxia on systemic vasculature.

Effects of hypoxic hypoxia (HH) on cardiac output (CO), CO distribution, arterial and venous pressure-flow curves, vascular compliance, vascular time constant (tau), and resistance to venous return (RVR) were evaluated on six dogs. The vascular bed was isolated into four compartments depending on venous drainage: superior vena cava (SVC), splanchnic, renal and adrenal, and the remainder of the inferior vena cava (IVC). Low arterial O2 content and PO2 produced a threefold increase in CO at the same mean arterial pressure and a significant redistribution of CO to the SVC. Arterial pressure-flow curves decreased their slope (i.e., flow resistance) by a factor of two in the IVC and renal beds and by a factor of three in the splanchnic and SVC beds. Venous pressure-flow curves for the animal also decreased their slope significantly. HH causes a twofold increase in venous compliance and in mean venous pressure; tau did not change, but RVR halved. Seventy percent of the CO increase is explained by the increase in mean venous pressure and 30% by the reduction in RVR.

Acid-Base Equilibrium↗