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Biomedical subjects

R Engelman

Publications and source records attributed to R Engelman.

15 recordsLinked to original sources
PubMed2000

Human population in the biodiversity hotspots.

Biologists have identified 25 areas, called biodiversity hotspots, that are especially rich in endemic species and particularly threatened by human activities. The human population dynamics of these areas, however, are not well quantified. Here we report estimates of key demographic variables for each hotspot, and for three extensive tropical forest areas that are less immediately threatened. We estimate that in 1995 more than 1.1 billion people, nearly 20% of world population, were living within the hotspots, an area covering about 12% of Earth's terrestrial surface. We estimate that the population growth rate in the hotspots (1995-2000) is 1.8% yr(-1), substantially higher than the population growth rate of the world as a whole (1.3% yr(-1)) and above that of the developing countries (1.6% yr(-1)). These results suggest that substantial human-induced environmental changes are likely to continue in the hotspots and that demographic change remains an important factor in global biodiversity conservation. The results also underline the potential conservation significance of the continuing worldwide declines in human fertility and of policies and programs that influence human migration.

Conservation of Natural Resources↗
PubMed1999

Persistent effects of doxorubicin on cardiac gene expression.

During administration of the anthracycline antitumour agents, their cardiotoxicity can progress from cardiac dysfunction to heart failure. Cardiomyopathy can also develop years after receiving anthracyclines. To determine if persistent and/or progressive anthracycline effect(s) are referable to anthracycline effects on cardiac gene expression, steady-state mRNA levels were determined 4 days (n=8), 4 weeks (n=7) and 10 weeks (n=7) after doxorubicin (DOX; 2 mg/kg IV) in a well-characterized rabbit model. Levels of mRNA for alpha -actin, beta -myosin heavy chain and the calcium pump of the sarcoplasmic reticulum (SERCA2a) in the left ventricle (LV) were determined by Northern blot hybridization and expressed relative to an 18S constitutive marker. The mRNA levels for the high molecular weight subunit (cardiac isoform) of the ryanodine receptor (RyR2), sarcolemmal calcium channel (dihydropyridine receptor; DHPR), angiotensin-converting enzyme (ACE), angiotensin II receptor (ATR) and atrial naturetic peptide prohormone (ANP) were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analysis, and expressed relative to GAPDH, a constitutive marker. Histopathologic evidence for anthracycline-induced myocardial cell injury was absent (score <1) in all hearts examined except one (score=1.1; 4 weeks post-DOX), which was considered separately. Relative mRNA levels for beta -myosin heavy chain 4 days after DOX increased 1.9-fold compared to the vehicle-treated group, but by 4 weeks levels had returned to baseline. Relative mRNA levels for DHPR were increased 1.2-fold 4 days after DOX and were persistently increased 1.9- and 2.2-fold 4 and 10 weeks after DOX, respectively. The mRNA levels for ANP were first decreased (4.5-fold) 4 days after DOX. Four weeks after DOX, ANP message levels approached Control in seven out of eight rabbits. The one rabbit with early LV histopathology 4 weeks post-DOX had increased mRNA for DHPR (2.7-fold) and ANP (80-fold). Between 4 and 10 weeks after DOX, mRNA levels for ANP increased C 16-fold: evidence for late progression. In situ hybridization with specific riboprobes localized the persistent increase in DHPR and the progressive increase in ANP to myocytes. Thus, DOX alters steady-state mRNA levels in LV that are referable to both persistent and progressive anthracycline effects on myocellular gene expression.

Animals↗
PubMed1998

Preoperative diagnostics in pancreatic carcinoma: would less be better?

OBJECTIVE: The objective of this study was to investigate the value of preoperative diagnostics in patients with pancreatic carcinoma in terms of tumor diagnosis and evaluation of resectability. PATIENTS/METHODS: From 1 September 1985 to 31 December 1997, 408 patients shown by histology to have a ductal (n=330) or periampullary carcinoma (n=78) were treated at our hospital. RESULTS: In determining the presence of tumor, ultrasonography and computed tomography (CT) had a sensitivity of 88.3% and 94.0%, respectively; combined, they had a sensitivity of 96.2%. Endoscopic retrograde cholangiopancreatography (ERCP) had a sensitivity of 96.2%. Preoperative aspiration biopsy cytology had a sensitivity of 71.4%. No correlation was found in the patients undergoing surgery between the preoperative level of serum CA 19-9 and the presence of distant metastases. Tumor infiltration of the portal vein was shown with a sensitivity of 33.3%, 24.3%, and 76.5% and a specificity of 93.9%, 98.9%, and 65.6% by ultrasonography, CT, and angiography, respectively. Ultrasonography and CT detected liver metastases or peritoneal carcinomatosis with a sensitivity of 35.9% each and a specificity of 91.9% and 91.7%, respectively. CONCLUSION: This study shows that, in 96% of patients with pancreatic carcinoma, ultrasonography and CT are adequate for diagnosis and for the evaluation of resectability. ERCP is not the method of choice in the diagnosis of pancreatic carcinoma due to its invasiveness and to the fact that it fails to demonstrate the pathological anatomical location of the tumor; it should only be used if a tumor is suspected despite negative results on ultrasonography and CT or as an additional diagnostic method to differentiate between chronic pancreatitis and carcinoma. On account of the low sensitivity of percutaneous aspiration biopsy cytology, this method is not necessary preoperatively and may even lead to the spread of tumor cells. In 7% of patients, routine laparoscopy would additionally show liver metastases or peritoneal carcinomatosis not demonstrated using the imaging techniques.

Adult↗
PubMed1990

Experimental approaches to nutrition and cancer: fats, calories, vitamins and minerals.

Chronic energy intake restriction (CEIR) inhibits lymphoproliferative disease, autoimmune-based renal disease and mammary adenocarcinoma in mice of numerous short-lived strains (MRL/lpr, C3H/Bi, C3H/Ou). Doubling and tripling of life span and health span and inhibition of development of diseases associated with aging could be attributed to restriction of calories but not to restriction of dietary fat in the absence of calorie restriction. In mice of both long- and short-lived strains, CEIR dramatically prevents the waning of immunologic vigor that commonly occurs with aging, delays thymic involution, impairs formation of circulating immune complexes, prevents the renal injury that accompanies autoimmune disease, and significantly forestalls development of genetically determined lymphoproliferative or neoplastic disease. Evidence suggests that CEIR may exert these beneficial influences in part through regulation of cellular proliferation. Trace elements, particularly zinc, as well as vitamins may play important roles in maintaining immunocompetence and also appear to be of significance in the dietary prevention of certain experimental cancers.

Animals↗
PubMed1979

Pulmonary lymphangiomyomatosis.

Pulmonary lymphangiomyomatosis is a rare but distinct clinical and pathological entity. It is characterized by hamartomatous proliferation of smooth muscle around the lymphatic vessels of the lung, mediastinum, and retroperitoneum. It occurs only in menstruating women and girls and is manifested by spontaneous pneumothorax and chylous pleural or abdominal effusion. As it progresses, the lungs become increasingly involved with subsequent pulmonary insufficiency and recurrent infection. Eventually death results. This entity has not been reported previously in the surgical literature even though the thoracic surgeon is called on to both establish the diagnosis and aid in palliation. The hypothesis that the disease is estrogen dependent is reviewed and the desirability of estrogen ablation in patients with positive estrogen receptors is suggested.

Abdominal Neoplasms↗
PubMed1977

Does intermittent coronary perfusion offer greater myocardial protection than continuous aortic cross-clamping?

There has been considerable controversy concerning the relative merits of intermittent coronary perfusion vs. continuous aortic cross-clamping for cardiac procedures requiring ischemic arrest. Using the isovolumic ventricular balloon model and "stop-freeze" biopsy techniques, myocardial contractility (LV dp/dt max, length-tension, and force-velocity relationships) and metabolism (adenine nucleotides, creatine phosphate, and glycogen) were studied in 46 intact dogs supported by normothermic cardiopulmonary bypass and subjected to either 60 minutes of continuous ischemic arrest or to four 15-minute intervals of ischemia each followed by 5 minutes of reperfusion. Following ischemia the hearts were reperfused for 30 minutes and defibrillated after the first 10 minutes. There were no significant differences in either metabolic parameters or contractile function between the groups. Although partial regeneration of adenosine triphosphate and glycogen occurred during reperfusion, only creatine phosphate achieved normal values and the end result was no difference between the two techniques. These data indicate that 5 minutes of coronary reperfusion between consecutive episodes of ischemic arrest affords no greater intraoperative protection of the myocardium than does continuous aortic cross-clamping.

Adenine Nucleotides↗
PubMedDate not supplied

The physician as student.

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Education, Medical, Continuing↗