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Biomedical subjects

J E Jackson

Publications and source records attributed to J E Jackson.

At least 91 records · Page 5Linked to original sources
PubMed1992

Evaluation of plant extracts for antileishmanial activity using a mechanism-based radiorespirometric microtechnique (RAM).

Extracts of eleven plants used in Nigerian traditional medicine have been evaluated for possible antileishmanial activity using a radiorespirometric microtest technique based on in vitro inhibition of catabolism of 14CO2 from a battery of 14C-substrates by promastigotes. Of 13 methanol extracts tested, 5 from Gongronema latifolia, Dorstenia multiradiata, Picralima nitida, Cola attiensis, and Desmodium gangeticum, were active at concentrations of 50 micrograms/ml or less against a visceral Leishmania isolate.

Animals↗
PubMed1992

Quantification of right to left shunt at rest and during exercise in patients with pulmonary arteriovenous malformations.

BACKGROUND: Current treatment of patients with pulmonary arteriovenous malformations requires serial embolisations by means of steel coils or balloons. Measurement of right to left shunt is the most specific index of response to treatment. A new method of measuring shunt has been developed that is less invasive than traditional methods. METHODS: Right to left pulmonary shunt (expressed as percentage of cardiac output) was measured at rest in 19 patients with pulmonary arteriovenous malformations and six normal subjects by using intravenously injected albumin microspheres labelled with technetium-99m. The technique was compared with a simultaneous shunt measurement in subjects breathing 100% oxygen while they rested. The microsphere technique was adapted to measure the right to left shunt during exercise in 12 patients and five normal subjects with a new method of quantification. RESULTS: The mean (SD) shunt at rest as measured by the microsphere method was 23.2% (15.6%) in the patients and 2.7% (1.2%) in the normal subjects. When these values were compared with those of the 100% oxygen method the difference in mean values was 1% and the limits of agreement between the two methods -32% to +45%. The microsphere method is less invasive (arterial blood gas sampling is not required), quicker, and more comfortable for patients than the 100% oxygen method. In five of the normal subjects the mean (SD) 99mTc microsphere shunt increased from 2.9% (1.3%) at rest to 5.1% (2.9%) during exercise. In the 12 patients studied during exercise the shunt increased from 33.7% (12.7%) at rest to 41.7% (13.3%) during exercise in eight but decreased from 22.6% (2.4%) at rest to 17.6% (2.2%) during exercise in four. Arterial desaturation during exercise correlated with change in the size of the right to left shunt during exercise (r = +0.80). CONCLUSIONS: The microsphere method allows measurement of right to left shunt at rest and during exercise. Serial measurements at rest provide a simple, safe assessment of the physiological response to embolisation in patients with pulmonary arteriovenous malformations.

Adolescent↗
PubMed1992

Insertion of Hickman central venous catheters by using angiographic techniques in patients with hematologic disorders.

During a 9-month period, 69 Hickman catheters were successfully inserted by using angiographic techniques in 59 patients with hematologic disorders. A pneumothorax, which did not require drainage, developed in one patient. No other significant complications occurred at the time of insertion. Eighteen catheters were removed electively, 15 are still in situ, six were removed for thrombosis, and five were accidentally removed. Infection precipitated removal in six subjects. Ten patients died with the catheter in place. Five catheters were removed in patients with refractory septicemia of unknown origin. One catheter burst during an injection and had to be removed. Three patients were lost to follow-up. There were 3.24 infectious episodes per 1000 days of catheterization, more than twice the rate found in some other series. The results of this study are compatible with the growing body of evidence in favor of the angiographic insertion of Hickman catheters. The apparently high rate of infection is ascribed to factors other than insertion in the angiography suite, including the high proportion of bone marrow transplantation patients.

Adolescent↗
PubMed1991

An antigen immunologically related to the external domain of gp185 is shed from nude mouse tumors overexpressing the c-erbB-2 (HER-2/neu) oncogene.

An antigen, immunologically related to the external domain of the c-erbB-2 (HER-2/neu) protein, was found shed into the serum of nude mice bearing tumors that overexpress the c-erbB-2 protein (gp185). Utilizing paired combinations from a panel of monoclonal antibodies (TAbs 250-265), with specificity for extracellular epitopes of gp185, an immunoradiometric assay was developed to quantitate this shed antigen. The immunoradiometric assay detected membrane-bound and soluble gp185 as well as a soluble derivative corresponding in sequence to the extracellular domain of gp185 (designated gp75). This recombinantly expressed gp75 was immunoaffinity purified and used to generate a standard curve from which serum samples were quantitated. Increases in antigen levels measured in the sera of tumor-bearing nude mice correlated with both overexpression of the c-erbB-2 protein and increased tumor volume. Positive sera were obtained from mice given implants of NIH3T3 cells transfected with c-erbB-2 complementary DNA (NIH3T3t), or ovarian (SK-OV-3) or breast (MDA-MB-361) tumor cell lines overexpressing the c-erbB-2 protein. In mice bearing NIH3T3t tumors, increases in tumor volume from 80 to 9000 mm3 resulted in levels of shed antigen from 8 to greater than 1000 ng/ml gp75 equivalents. Sera from mice with c-erbB-2-negative tumors or tumors overexpressing the epidermal growth factor receptor were negative in the assay. This assay, and the quantitation of shed antigen levels, may have diagnostic or monitoring utility in cancers, such as breast and ovarian, in which the c-erbB-2 protein is overexpressed.

Animals↗
PubMed1991

Percutaneous transcaval tumour biopsy using a 'road-map' technique.

The 'road-map' facility available on some of the commercially available digital subtraction angiography units is usually used to aid in the selective catheterization of a vessel during arteriography. We describe its use in the percutaneous transcaval biopsy of tumour within the inferior vena cava (IVC).

Aged↗
PubMed1991

Relative lack of toxicity of transplatin compared with cisplatin in rodents.

The differential toxicity of the cis- and trans-isomers of diamminedichloroplatinum (II) (cisplatin and transplatin) was investigated in rats and guinea pigs. In both species, repeated daily administration of 1 to 2 mg per kg cisplatin produced severe histological and/or functional damage to renal and gastro-intestinal systems and resulted in death of the animals. Quantification of tissue platinum by atomic absorption spectroscopy demonstrated accumulation of large amounts of platinum in the kidney of the animals, with lesser amounts in the liver and gastro-intestinal tract. Transplatin, administered at total doses two- to four-fold that of cisplatin, was essentially non-toxic by histological and functional assessment. However, the amounts of tissue platinum measured in transplatin-treated animals were no smaller than those measured in cisplatin-treated animals; indeed, platinum concentrations in kidneys of transplatin-treated rats were more than 2.5 times those in cisplatin-treated rats. Thus tissue platinum content did not correlate with organ damage. These data suggest that mechanism(s) involving steric interactions of platinum species, perhaps with cellular macromolecules such as DNA or RNA, may be important in the differential toxicity of these two compounds.

Animals↗
PubMed1991

Factors affecting bone mineral density in elderly men receiving chronic in-center hemodialysis.

Twenty-five elderly men receiving chronic hemodialysis had measurements of their bone mineral density (BMD) by dual-photon absorptiometry (DPA). Loss of BMD was much more pronounced in femoral necks than in lumbar vertebrae. Stepwise multiple liner-regression analysis showed that low BMD was associated with 1) hypoalbuminemia, hypermagnesemia, hyperaluminemia, and high serum alkaline phosphatase for femoral necks and 2) hypercalcemia and hypermagnesemia for lumbar vertebrae. These observations suggest that the femoral neck is the preferred site for measurement of BMD in dialysis patients. Along with factors directly affecting bone metabolism, nutritional factors may affect BMD in such patients.

Absorptiometry, Photon↗
PubMed1991

Recommendations for a change in living situation resulting from an outpatient geriatric assessment: type, frequency and risk factors.

We analyzed the outcomes of 480 comprehensive outpatient geriatric assessments to determine the frequency of recommendations for home help or a change in residence and to determine whether simple clinical observations could predict such recommendations. Fifty-eight percent (280) of the patients received no recommendation for a change in the living situation. Of the 200 patients receiving a recommendation for a change in living situation, 97 (49%) were felt to be able to stay at home with increased in-home support and/or day care, and 51.5% (103) were advised to seek placement. After adjusting for age and gender, risk factors predicting a recommendation for change were dementia (odds-ratio = 9.98), vision deficits (odds ratio = 2.02), lower education level compared to college (odds-ratio = 1.88 high school, 1.42 for less than high school), an increasing number of medical diagnoses (odds-ratio = 1.49 per diagnosis), and a functional impairment on the Katz index (odds-ratio = 1.09). The presence of these risk factors should lead to consideration of further evaluation of the home environment in this study. We conclude that geriatric patients presenting for a comprehensive outpatient evaluation commonly need a change in home situation, though most can remain in their home, and that simple clinical observations can be helpful in screening patients for further evaluation of their home environment.

Aged↗
PubMed1990

Coil embolization of pulmonary arteriovenous malformations.

Pulmonary arteriovenous malformations (PAVMs) are uncommon lesions that can be treated by surgery or interventional radiology. Forty-four PAVMs in 11 patients were occluded by transcatheter coil embolization with only one symptomatic complication, deep venous thrombosis, attributable to the procedure. There was a significant improvement in symptoms and a reduction in pulmonary AV shunting in the 9 patients in whom embolization of all visible discrete lesions was successfully completed. Coil embolization is an effective alternative to other methods of treating PAVMs.

Adolescent↗
PubMed1990

Teaching the multidisciplinary team approach in a geriatrics miniresidency.

The miniresidency program in geriatrics begun in 1985 at the University of California, San Diego, School of Medicine acquaints practicing health professionals with a multidisciplinary team approach to the care of geriatric patients. The two-week program features participation in a multidisciplinary outpatient clinic, home visits, social work and nutrition consultations, and conferences with patients and families. Miniresidency members also participate in neurologic and neuropsychological evaluations and attend day care for demented adults. The 71 health professionals who completed the program during its first 20 months showed significant improvement on their scores between the pre- and posttests: the mean of all scores in the pretest was 51 out of a possible 80 (SD 15); the mean of all scores in the posttest was 75 out of a possible 80 (SD 4); p less than .001. The 77% who returned post-program evaluation questionnaires found the program "useful" or "very useful."

Geriatrics↗
PubMed1990

Cognitive function testing in comprehensive geriatric assessment. A comparison of cognitive test performance in residential and clinic settings.

Tests of cognitive function are frequently used in geriatric assessment, but the effect of test setting has rarely been explored. To determine the effect of testing site on the performance of elderly patients undergoing a comprehensive geriatric assessment, we administered the Mini-Mental State Exam to 116 geriatric patients in the clinic and at their residence. Their cognitive abilities varied from normal to severely impaired. The patients' scores were 1.5 +/- 3.6 (mean +/- SD) higher at their residence. The clinical importance of a difference in score of 1.5 is not clear. For this reason a second analysis was performed in which a difference in scores of five points or greater between settings was considered clinically meaningful. Twenty-five percent (29 of 116) differed by five points or more. Of these 29 patients, 22 (76%) tested better in the residential setting. These differences were statistically significant (P = .001). We conclude that the testing site may affect test performance and that in-home assessment may reveal the optimal cognitive function of geriatric patients.

Aged↗
PubMed1990

Effect of percutaneous transcatheter embolization on pulmonary function, right-to-left shunt, and arterial oxygenation in patients with pulmonary arteriovenous malformations.

The effects of percutaneous transcatheter embolization on pulmonary function and exercise capacity were assessed in 15 patients with pulmonary arteriovenous malformations (PAVM). Vital capacity (VC), FEV1, DLCO, SaO2, exercise performance, and right-to-left shunt (100% oxygen method) were measured before and 2 to 6 months after treatment. Surgical correction had been attempted in 9 patients prior to referral, and 11 had associated hereditary hemorrhagic telangiectasia (HHT). Lung function tests before intervention showed normal VC and FEV1/VC ratios, reduced DLCO (mean 71% predicted, range 36 to 123%), a resting supine SaO2 of 86% (range 67 to 95%) and mean shunt fraction of 33% (range 15 to 47%). Despite further marked falls in SaO2 on exertion, exercise capacity was well preserved. Following steel coil embolization of all PAVM with a feed vessel internal diameter greater than 3 mm (one to four sessions per patient), mean shunt fraction improved from 33 to 19% and resting SaO2 from 86 to 92% with no change in VC. A consistent improvement in diffusing capacity was seen only in patients with coexisting HHT. Exercise capacity increased in the majority (unchanged in 6), and SaO2 during maximal exercise improved in all except one patient. There were no long-term complications following embolization. These findings indicate that embolization of all macroscopic PAVM, undertaken primarily to reduce the risk of paradoxical embolization, is safe and results in substantial improvements in resting and exercise SaO2 without evidence of loss of normal lung. The right-to-left shunts remaining following embolization may reflect the presence of numerous microscopic PAVM in these patients.

Adolescent↗
PubMed1990

Biliary endoprosthesis dysfunction in patients with malignant hilar tumors: successful treatment by percutaneous replacement of the stent.

Symptoms caused by malignant hilar bile duct tumors are often palliated by the insertion of a percutaneous biliary endoprosthesis. However, these often occlude early and may be difficult to replace. We have reviewed our experience with percutaneous replacement of endoprostheses in 17 patients with 31 episodes of stent dysfunction. The stent was changed successfully in 30 of the 31 attempts. The average durations of initial and subsequent stent patencies were 28 and 20 weeks, respectively. Significant acute complications occurred in three patients, one of whom had a perihepatic abscess and two of whom had septicemia. Two patients died within 30 days of their last stent change. The one patient in whom attempted insertion of a new stent was unsuccessful had to remain on continuous external catheter drainage. The occluded or migrated endoprosthesis was successfully removed either percutaneously (55%) or endoscopically (26%) in 25 of the 31 cases. Successful removal of the stent and reinsertion after blockage or migration is possible in most patients. Our experience suggests that patients with malignant obstruction of the bile duct should not be refused an indwelling endoprosthesis just because of the frequent occurrence of early occlusion of the stent.

Adenoma, Bile Duct↗
PubMed1990

Quantitative in vitro drug potency and drug susceptibility evaluation of Leishmania ssp. from patients unresponsive to pentavalent antimony therapy.

Quantitative in vitro drug sensitivity of 32 Leishmania isolates (16 from patients failing pentavalent antimony [SbV] therapy) was determined using a radiorespirometric microtechnique (RAM). Of 30 isolates with histories, 22 (73%) RAM tests agreed with patient history; the remaining 8 (27%) did not. There was no difference in RAM drug sensitivity: clinical correlation between 15 isolates tested blindly and 15 with known clinical history (4 did not agree with clinical history in both). Test sensitivity appeared to be limited only by the sensitivity of the Leishmania to SbV and could be detected at 2 micrograms/ml Sb (about 10% of serum drug level). An isolate from a patient with untreated self-healing cutaneous disease was drug resistant. Using RAM, parasite drug sensitivity can be quantified apart from patient physiologic and immunologic variables intrinsic to clinical data. Potency differed a maximum of 100% (weight% Sb:weight% Sb) among drug lots and also between Glucantime and Pentostam. Potency changes between drug lots were not explainable based on Sb content or test-to-test variability. This microtest offers a rapid method for evaluating the drug sensitivity of patient isolates and for determining of the activity of pentavalent antimonials and other candidate anti-leishmanials prior to the initiation of therapy.

Adenosine↗