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Biomedical subjects

J E Lowe

Publications and source records attributed to J E Lowe.

At least 127 records · Page 7Linked to original sources
PubMed1989

Comparison of detomidine, butorphanol, flunixin meglumine and xylazine in clinical cases of equine colic.

Detomidine hydrochloride, butorphanol tartrate, flunixin meglumine and xylazine hydrochloride were evaluated in a blind multi-centre clinical trial in 152 horses with abdominal pain. The drugs were administered as follows: detomidine 20 or 40 micrograms/kg bodyweight (bwt); butorphanol 0.1 mg/kg bwt; flunixin meglumine 1.0 mg/kg bwt; xylazine hydrochloride 0.5 mg/kg bwt. Each centre compared responses to the two doses of detomidine with those to one of the other analgesics. The drugs were administered intravenously (i.v.) after clinical assessment of the degree of sweating, kicking, pawing, head and body movement, attitude, lip curling, stretching to urinate, pulse rate, respiratory rate and rectal temperature. Similar assessments were repeated at 15 min intervals for at least 1 h. The investigators ranked the response to treatment from 'not satisfactory' to 'highly satisfactory'. Significant differences in sweating, kicking, pawing, head and body movement, attitude, pulse rate and respiratory rate were noted between the horses receiving butorphanol and either dose of detomidine. The investigators' subjective evaluation of the analgesic and sedative effects of either dose of detomidine were significantly better than for butorphanol. Analgesia was rated as highly satisfactory or satisfactory in 93.3 per cent and 6.7 per cent of the horses receiving 40 micrograms/kg bwt of detomidine, 73.3 per cent and 26.7 per cent of the horses receiving 20 micrograms/kg bwt of detomidine, and none of the horses receiving butorphanol. There were no differences in the incidence of side effects with the two compounds. Significant differences were noted in kicking, pawing, head and body movement and attitude between the horses receiving flunixin meglumine and either dose of detomidine. Flunixin meglumine provided significantly less analgesia than either dose of detomidine. Analgesia was rated as highly satisfactory or satisfactory in 73.7 per cent and 21.0 per cent of the horses receiving 40 micrograms/kg bwt of detomidine, 42.9 per cent and 21.4 per cent of the horses receiving 20 micrograms/kg bwt of detomidine, and 6.3 per cent and 37.5 per cent of the horses receiving xylazine. Sedation was considered to be at least satisfactory in 84.2 per cent of the horses receiving 40 micrograms/kg of detomidine, 71.5 per cent of the horses receiving 20 micrograms/kg of detomidine and 53.3 per cent of the horses receiving xylazine.

Adrenergic alpha-Agonists↗
PubMed1988

SV 40-transformed normal and DNA-repair-deficient human fibroblasts can be transfected with high frequency but retain only limited amounts of integrated DNA.

The ability of simian virus 40-transformed human fibroblasts to integrate and maintain transfected genomic DNA has been investigated in two normal and six DNA-repair-deficient human cell lines. These cell lines were transfected with DNA containing two selective markers (G418 and hygromycin (Hyg) resistance) separated by random pieces of human DNA of 0-40 kb in length. The transfection frequency for the selected (G418R) marker was between 2 x 10(-4) and 2 x 10(-3) for all cell lines, comparable to many other mammalian systems. About 50% of the G418R colonies were also initially resistant to Hyg. Analysis of the DNA from individual clones expanded for a further month revealed, however, that about one to three copies of the selected marker but only about 0.1 copy per cell of the unselected marker were maintained. Our results were broadly similar for all eight cell lines. Thus the amount of integrated DNA that is stably maintained in these cells is in general very small (less than 50 kb). This may provide an explanation for the difficulties encountered in many laboratories in attempts to correct the defect in DNA-repair-deficient human cells by transfection with genomic DNA. Our results also show that none of several defects in DNA repair has any obvious effect on either the transfection frequency or the amount of stably integrated foreign DNA.

Cell Transformation, Viral↗
PubMed1988

Chondrosarcoma metastatic to the heart.

This review summarizes the clinical manifestations and results of treatment of chondrosarcoma metastatic to the heart. Including the patient in the present report, a total of 18 patients have been reported. The most common site of cardiac metastasis was the right atrium. Dyspnea and pleuritic chest pain were the most common symptoms associated with cardiac metastases. The median time from the initial diagnosis of primary chondrosarcoma to death was 36 months, and the median time from the initiation of cardiac symptoms to death was 2 months. Treatment of primary chondrosarcoma included local radical resection in 14 patients. Treatment of cardiac metastases consisted of palliative support in 13 patients and surgical resection in 5 patients. Median survival following the development of cardiac symptoms was 2 months for patients treated nonsurgically and 18 months for those who underwent resection of cardiac metastases. The longest survival (24 and 28 months) was obtained in 2 patients with metastases confined to the heart that were successfully resected soon after development of cardiac symptoms. These results suggest that surgical resection of cardiac metastases in patients without widespread other metastases can result in substantial prolongation of life.

Chondrosarcoma↗
PubMed1988

Effects of distant potentials on unipolar electrograms in an animal model utilizing the right ventricular isolation procedure.

The effects of distant potentials on local epicardial unipolar electrograms were examined utilizing a model that enabled both ventricles to be paced independently in five dogs. The right ventricular isolation procedure electrically isolates the right from the left ventricle. Right ventricular electrograms were separated into their local (right ventricular) and distant (left ventricular) components by altering the left-right ventricular pacing interval. Waveform configuration, peak to peak amplitude, magnitude of the slope and timing of the fastest downstroke were carefully evaluated at each electrode site, both with and without the presence of distant left ventricular potentials. Except for the timing of the fastest downstroke, all of these variables were significantly altered by distant potentials. Although the slope of the fastest downstroke was significantly affected by distant potentials, it remained a sensitive indicator of local versus distant activation. All electrograms of local right ventricular activation had a slope magnitude greater than 2.5 mV/2 ms whereas none of the right ventricular electrograms containing only distant left ventricular activity had a magnitude greater than 2.5 mV/2 ms. Computer-generated electrograms were calculated by digitally summing the recorded local right and distant left ventricular components. The simulated electrograms correlated well with the recorded electrograms during synchronous ventricular pacing. Thus, the configuration, amplitude and slope of unipolar electrodes were profoundly influenced by distant potentials. The timing of the fastest downstroke is largely independent of the effect of distant potentials and most closely represents local activation. The magnitude of the slope of the recorded electrogram accurately distinguishes local from distant activation.

Action Potentials↗
PubMed1988

Decision for surgery.

Based on the clinical impression and the current knowledge of the clinical variables (rectal examination, abdominal distention, abdominal fluid, intractable pain) most likely to differentiate between medical and surgical cases, three decision trees are provided as a guide to making the management decision in a horse with abdominal pain. Prior elimination of horses with limited life expectancy because of age or function or where financial constraints are present is understood. It must be emphasized that most of the information presently available originates from referral centers where the prevalence of surgical candidates is much higher than in general practice. This would influence the accuracy of the clinician in identifying horses with a surgical lesion or estimating survival (positive predictive value).

Abdomen, Acute↗
PubMed1988

Myocardial tolerance to total ischemia in the dog anesthetized with halothane or isoflurane.

Myocardial tolerance to total ischemia was compared in animals anesthetized with halothane or isoflurane by measuring the time required for development of cardiac rigor in the absence of coronary circulation or wall stress. Sixteen dogs, eight in each group, were anesthetized with equally potent inspired concentrations of either halothane (2 MAC) or isoflurane (2 MAC), intubated, and ventilated. Thirty minutes later, the heart was rapidly excised. A left ventricular slab was prepared and maintained at 37 degrees C. A portion of each slab was placed in a compressibility gauge that detects rigor onset by an abrupt increase in resistance to tissue deformation. Subendocardial tissue pressure was continuously measured in a second slab using needle-tipped Millar pressure transducers. A third slab was used for intermittent tissue sampling and HPLC assay of high-energy nucleotide levels. There were no differences in pre-ischemic heart rate, mean arterial pressure, glucose, lactate, PO2, PCO2, pH, plasma epinephrine, or norepinephrine levels between the two groups. The onset of rigor as measured by the compressibility gauge was delayed in the halothane group (68 +/- 7.2 vs. 60 +/- 5.0 min; P less than .05). Tissue ATP and ADP levels declined throughout the period of ischemia, with a trend towards preservation in the halothane group. The data show that myocardial tolerance to total normothermic ischemia is improved in animals anesthetized with halothane compared to isoflurane, independent of the effects on hemodynamics or collateral coronary circulation.

Adaptation, Physiological↗
PubMed1988

Quantitative analysis of right and left ventricular infarction in the presence of postinfarction ventricular septal defect.

To quantitate the amount of right and left ventricular infarction in patients dying with postinfarction ventricular septal defect (PIVSD), hearts from 54 patients with anterior or inferior myocardial infarction were studied at autopsy. Fifteen hearts had myocardial infarction with PIVSD and 39 hearts had infarction without PIVSD and were used as a comparison group. All infarcts were sized histologically and the percent of each ventricle infarcted was quantitated by computer-assisted planimetry. The pathologic substrate for PIVSD was diffuse coronary artery disease with acute thrombosis resulting in transmural confluent infarction. Within the PIVSD group, there was significantly more left ventricle involved in anterior infarctions than in inferior infarctions (p less than .04). Conversely, there was more right ventricular infarction in inferiorly located myocardial infarctions with resulting PIVSD (p = .059). When infarctions resulting in PIVSD were compared with infarctions not resulting in PIVSD, the PIVSD group was characterized by larger left and right ventricular infarcts irrespective of infarct location (p less than .003). The incidence of right ventricular infarction was 100% in the PIVSD group (p less than .0001). Twelve of the 15 patients with PIVSD (80%) developed cardiogenic shock within 48 hr of septal rupture. The high incidence of shock and the rapid deterioration may have been secondary to right ventricular infarction in these patients. Therefore, infarcts resulting in PIVSD and subsequent death are characterized by a high incidence of right ventricular infarction. Significantly more infarction of the right ventricle is seen in either anterior or inferior infarctions resulting in PIVSD compared with infarctions not resulting in PIVSD. PIVSD complicating inferior infarctions is associated with the greatest amount of right ventricular infarction.

Aged↗
PubMed1988

Diagnosis and course of nephrogenic ascites.

Nephrogenic ascites is a complex diagnostic problem with poorly understood pathophysiology. Morbidity and eventual mortality from this ongoing problem are significant. The diagnosis of nephrogenic ascites must be established by exclusion. We report the cases of nine patients investigated between 1978 and 1985. Laparoscopy, which was utilized in all nine patients, led to a specific diagnosis in two. We believe that a vigorous diagnostic evaluation, including laparoscopy, is essential in patients with chronic renal failure who develop persistent ascites.

Adult↗
PubMed1988

A clinical comparison of mitral valve repair versus valve replacement in ischemic mitral regurgitation.

Severe mitral regurgitation caused by acute myocardial infarction has been a particularly difficult management problem with disappointing clinical results. Over a 75-month period, ending March 31, 1987, 611 patients underwent mitral valve operations at Duke University Medical Center. Within this group, 55 patients had clearly defined ischemic mitral regurgitation, and 37 of these required emergency operations. Thirty-one of the 55 patients had isolated posterior papillary muscle dysfunction, nine had papillary muscle rupture, and 15 had severe ventricular dysfunction and generalized annular dilatation. Thirty-two patients were treated with primary mitral valve replacement, and 23 had mitral valve repair. In 18, repair was accomplished by a transventricular approach, combining the techniques of commissural annuloplasty, papillary muscle shortening or reimplantation, and infarct exclusion. Transventricular mitral valve repair proved to be safe, expeditious, and effective in restoring valve competence. Although the repair and replacement groups were similar with respect to all relevant baseline characteristics, improved operative survival was observed after valve repair, as compared to replacement, both for the overall group (p = 0.03) and for acute papillary muscle dysfunction (p = 0.05). These data suggest that a policy of predominant mitral valve repair, when appropriately applied in patients with ischemic mitral regurgitation, offers the potential for improving therapeutic results.

Cardiopulmonary Bypass↗
PubMed1987

Autotransfer of Day 4 embryos from oviduct to oviduct versus oviduct to uterus in the mare.

Embryo autotransfer is defined as the collection of an embryo from and the transfer of this embryo into the same animal. The objectives of this study were to: 1) test the hypothesis that oviduct transport of the equine embryo from the oviduct into the uterus is not dependent on a unilateral embryo-corpus luteum interaction, 2) develop an embryo autotransfer technique for the mare and 3) compare the success rates of Day 4 embryos surgically autotransferred from the oviduct ipsilateral to ovulation to either the oviduct (n=10 mares) or the uterine horn (n=10 mares) contralateral to ovulation. Seventy percent (7 10 ) of the Day 4 embryos which were autotransferred to the oviduct contralateral to ovulation were transported through the oviduct and subsequently developed into embryonic vesicles detectable by ultrasonography between 10 and 21 days postovulation. This finding supported the hypothesis that oviductal embryo transport is not dependent upon the ipsilateral corpus luteum. Overall, sixty percent (12 20 ) of the autotransfers were successful. The success rate of uterine-transferred embryos was not significantly less (P>0.3) than that of oviductal-transferred embryos (5 10 vs 7 10 , respectively). Therefore, the Day 4 equine embryos were apparently mature enough to survive in the mare's uterus.

Journal Article↗
PubMed1987

Management of patients with heparin-associated thrombocytopenia and thrombosis requiring cardiac surgery.

Heparin-associated thrombocytopenia and thrombosis (HATT) is a serious complication of heparin therapy that results in intravascular platelet aggregation with arterial or venous thrombosis. Platelet aggregation to heparin in vitro is used to confirm the diagnosis. Cessation of heparin therapy with avoidance of reexposure to heparin is an important principle in the management of HATT. However, certain patients with HATT may require reexposure to heparin for emergency cardiac operations requiring cardiopulmonary bypass while still demonstrating positive in vitro platelet aggregation with heparin. The present report describes the management of 2 such patients. In each patient aspirin was shown to inhibit platelet aggregation to heparin in vitro; therefore, aspirin and dipyridamole were administered to each patient before heparin reexposure and continued throughout the perioperative period. Cardiopulmonary bypass with full heparinization was achieved without thrombotic or hemorrhagic complications in both patients. Despite the presence of a heparin-dependent platelet-aggregating factor in the plasma of these 2 patients, inhibition of platelet aggregation with aspirin and dipyridamole allowed uneventful reexposure to heparin.

Adult↗
PubMed1987

On-line detection of reversible myocardial ischemic injury by measurement of myocardial electrical impedance.

The metabolic and physiological alterations associated with changes in myocardial tissue electrical resistivity during ischemia were characterized to assess the feasibility of using such resistivity as an on-line indicator of the onset of ischemic injury. Twelve anesthetized dogs underwent rapid cardiac extirpation; 5 served as untreated controls, and 7 were pretreated with metoprolol tartrate. Beta blockade was used to alter the time course of ischemic injury as demonstrated previously in studies using this experimental model. In vitro measurement of myocardial resistivity, the detection of ischemic contracture, and serial measurements of tissue adenosine triphosphate (ATP) and lactate were obtained from totally ischemic left ventricles at 37 degrees C. Myocardial resistivity began to increase significantly before onset of ischemic contracture in the untreated control group (resistivity at 42.3 +/- 3.1 minutes, contracture at 53.8 +/- 3.7 minutes; p less than 0.025) as well as the metoprolol group (resistivity at 50.7 +/- 1.5 minutes, contracture at 70.0 +/- 3.5 minutes; p less than 0.005). As expected, ischemic contracture was delayed in the beta-blocked group compared with controls (p less than 0.01). Similarly, the onset of myocardial resistivity increase was delayed in the beta-blocked group (p less than 0.025). ATP and lactate levels at the onset of myocardial resistivity increase were consistent with severe but reversible injury. Resistivity changes during ischemia correlated linearly with simultaneous ATP depletion and lactate accumulation (r = 0.88 to 0.98; p less than 0.05). Furthermore, during global ischemia studied in 3 anesthetized dogs in vivo, the onset of myocardial resistivity increase occurred after 20 minutes. Finally, 6 anesthetized dogs underwent 60 minutes of in vivo regional ischemia by coronary artery occlusion, followed by 60 minutes of reperfusion. Myocardial resistivity in the ischemic region increased immediately and steadily after coronary occlusion, followed by a rapid decrease during subsequent reperfusion. These data show that myocardial resistivity may be useful for identifying severe but still reversible ischemic injury in on-line fashion during regional and global myocardial ischemia.

Adenosine Triphosphate↗
PubMed1987

Failure to detect a DNA repair-related defect in the transfection of ataxia-telangiectasia cells by enzymatically restricted plasmid.

We have transfected two SV40-transformed human fibroblast cell lines with plasmids in which double-strand breaks have been introduced by restriction enzymes, within or near the selected gene. Restriction of pSV2gpt with KpnI, as previously shown by Cox et al. (1986), reduced the frequency of transfection more in the ionizing radiation-sensitive ataxia-telangiectasia line AT5BIVA than in the resistant line MRC5V1. When the related plasmid pSV2neo was restricted with SmaI, the reduction in transfection was less in the ataxia-telangiectasia than in the normal cell line. Under our conditions, the apparent defect in transfection of AT5BIVA by pSV2gpt appears to be a result of the unusual sensitivity of the repair-deficient recipient to the selective agent. Loss of potential transfectants is exacerbated when transient gene expression is reduced by restriction of the plasmid. We suggest that a reduction in yield of transfectants with restricted plasmid in ataxia-telangiectasia cells cannot readily be used as evidence of a defect in DNA repair. Our results are also relevant to standard transfection experiments, since they emphasize the importance of optimizing selection when transient expression may be reduced, to ensure that potential transfectants are not killed by the selection regime.

Ataxia Telangiectasia↗
PubMed1987

Atrial lead perforation: a case report.

We report a patient in whom a chronic atrial lead perforated the right atrium and the right lung. This resulted in an hemopneumothorax and pneumomediastinum which was clearly documented by a chest computerized tomographic scan. The finding of pneumomediastinum should suggest atrial lead perforation. The utility of the chest computerized tomographic scan in diagnosing lead perforation is well illustrated by this case.

Aged↗
PubMed1987

A new sock electrode for recording epicardial activation from the human heart: one size fits all.

Simultaneous recording of epicardial activation from multiple sites during open heart surgery is essential for studying unstable ventricular arrhythmias. A previously described sock electrode array for this purpose requires custom-woven nylon sock material and expensive machined button electrodes. The limited compliance and elasticity of nylon requires that a new sock be individually fitted for each heart. Despite careful fitting, 17-20% of electrodes do not make satisfactory epicardial contact in dogs. Further, electrodes frequently dislodge from the sock and wires break at the button electrode solder joint. Recognizing these limitations, we formed a new sock from Xspan tubular dressing material and devised electrodes that attach securely to the sock. In six dogs, 90% +/- 3% of electrodes made satisfactory contact using the same Xspan sock, significantly (p less than .01) more than with the nylon sock despite far less labor. The same size X span sock with 60 snap electrodes was used to record from 27 human hearts of widely different dimensions. Satisfactory epicardial contact was obtained in 90% +/- 14% of electrodes in the 18 patients with Wolff-Parkinson-White syndrome (WPW) and 75% +/- 15% of electrodes in the nine patients with coronary artery disease. In no case did an accessory pathway fail to conduct following sock placement. The hemodynamic effect of the Xspan sock was evaluated in four dogs and was found to be minimal. Both the Xspan sock and the snap electrodes are easily made from inexpensive, readily available materials. The same Xspan sock accommodates a wide range of heart sizes, and the electrodes supported by the Xspan sock record significantly better and with less dislodgement and wire breakage than previous socks.

Animals↗
PubMed1987

Growth and calcium metabolism in horses fed varying levels of protein.

The effect of level of protein intake on growth and calcium metabolism was studied in 24 foals. Starting at four months old, the foals were fed one of three diets containing all nutrients, with the exception of protein, at levels recommended by the United States National Research Council Subcommittee on Horse Nutrition for a 12 month period. The protein levels in the three diets were 9 per cent (low protein) 14 per cent (NRC recommended level) and 20 per cent (high protein). The foals fed the low protein diet were changed to the high protein diet after 140 days when they were nine months old. There were no significant differences in the rates of growth in weight, height, cannon circumference or in hoof growth and feed utilisation of the horses fed the 14 or the 20 per cent protein diets. However, growth, feed intake and feed utilisation by the foals fed the low (9 per cent) protein diet were significantly depressed. The average daily gains for the first 140 days for the 9, 14 and 20 per cent protein treatment groups were 64, 631 and 687 g in weight, 0.57, 0.83 and 0.87 mm in height and 0.04, 0.13 and 0.14 m in forecannon circumference, respectively. The average daily feed intakes for the 140 day period for the three groups were 2.7, 4.4 and 4.7 kg, respectively. After the change to the high protein diet the foals that had been fed the low protein diet maintained a higher rate of gain in bodyweight, height and cannon circumference, and utilised feed more efficiently than the other two groups throughout the second 140 days of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗