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Biomedical subjects

R Graham

Publications and source records attributed to R Graham.

At least 181 records · Page 10Linked to original sources
PubMed1988

Modulation of tendon fibroplasia by exogenous electric currents.

A chicken tendon explant model system has been developed to investigate the effects of extremely-low-frequency (ELF), low-amplitude, unipolar, square wave pulsed electric fields on fibroplasia in vitro. An electric field parameter set consisting of 1-Hz, 1-ms duration pulses, with a time-averaged current density of 7 mA/m2 (peak current density 7 A/m2) induced maximal (32%) increase in fibroblast proliferation in tendon explants exposed for 4 days. Exposure to the same field at an average current density of 1.8 mA/m2 had no effect on fibroblast proliferation, whereas exposure to current densities on greater than 10 mA/m2 inhibited proliferation and relative collagen synthesis, without affecting noncollagen protein synthesis. Fibroplasia was significantly increased in explants oriented parallel to applied electric fields having current densities of 3.5 or 7 mA/m2, but there was no detectable effect on explants oriented perpendicular to the same electric field. Fibroblast proliferation and relative collagen synthesis were inversely proportional to donor age for chickens in the 3- to 16-week age group used in this study. For these dependent variables (proliferation and relative collagen synthesis), there was no interaction between donor age and ELF electric field exposure.

Animals↗
PubMed1988

In vitro activity of florphenicol.

Florphenicol was active at a lower concentration than chloramphenicol against over half of 234 recent clinical bacterial isolates. The majority (98%) of the isolates were inhibited by florphenicol at a concentration of 8 mg/l or less. Florphenicol was particularly effective against chloramphenicol resistant strains of Haemophilus influenzae. Klebsiella aerogenes and Bacteroides spp. Florphenicol was bacteristatic for salmonellae and Escherichia coli but bactericidal for Haemophilus influenzae. Florphenicol was slightly more active than chloramphenicol against Chlamydia trachomatis, Mycoplasma hominis and Mycoplasma pneumoniae but less active against Ureaplasma urealyticum.

Chloramphenicol↗
PubMed1988

The effect of hypertension, sodium, and race on isoproterenol sensitivity.

The heart rate response to isoproterenol is felt to be an index of beta receptor sensitivity. We studied this response in 55 normotensive and mildly hypertensive men on two dietary salt intakes (10 meq sodium per day, and 200 meq sodium per day). There was no relationship between receptor functioning and diagnosis of hypertension. Similarly, age, relative body weight, and resting plasma catecholamines were unrelated to the heart rate response to isoproterenol. There was however, a significant three-way interaction between race, diagnosis, and dietary salt. Black hypertensives fail to down regulate their beta receptors' response to isoproterenol in the face of a high salt challenge (p less than .006).

Adult↗
PubMed1987

Inverted papilloma: an uncommon benign cause of a ureteral filling defect.

A case of inverted papilloma of the ureter in a 62-year-old man is presented along with a literature review of 14 cases. This rare benign tumor should enter the differential diagnosis of a ureteral filling defect especially when it has a smooth configuration. Preoperative consideration of this diagnosis may lead to intraoperative confirmation of pathology and conservative resection.

Humans↗
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↗