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Biomedical subjects

G Gong

Publications and source records attributed to G Gong.

86 records · Page 5Linked to original sources
PubMed1993

Jarcho-Levin syndrome--a report of an autopsy case with cytogenetic analysis.

Jarcho-Levin syndrome (JLS) is a condition manifested by malformations of vertebral bodes and related ribs. There are two major subtypes spondylocostal dysostosis and spondylothoracic dysostosis, with different survival rates, associated malformations, and inheritance patterns. We have experienced an autopsy case of a premature female fetus with multiple congenital anomalies. She was 30 weeks of gestational age, born as the second baby of twins and expired shortly after birth. A post-mortem examination revealed multiple abnormalities including cervicothoracic hemivertebrae, a diminished number of right-sided ribs, and pulmonary hypoplasia with left diaphragmatic hernia. In addition, there were anomalous rotation of the foregut, unfused pancreas and anomalous drainage of the superior vena cava. Chromosomal analysis showed 46, XX, del(4)(q ter).

Abnormalities, Multiple↗
PubMed1993

Bioprosthetic cardiac valve degeneration: role of inflammatory and immune reactions.

Inflammatory and immune reactions are thought to mediate both calcification and biodegradation of bioprosthetic cardiac valve implants. To investigate the mechanisms of implant degeneration, we evaluated the role of inflammatory and immune reactions and the effects of tissue preservative treatment in three series of experiments. In the first experiment, three kinds of implants, i.e. glutaraldehyde-treated autograft Sprague-Dawley (SD) rat skin, xenograft Swiss-Webster (SW) mouse skin, and saline-treated autograft (control) were subcutaneously implanted in ten weanling SD rats, and retrieved after 70 days. There was no significant difference in the level of calcification in the autograft (113.13 +/- 27.09 micrograms/mg dry weight) and xenograft (78.27 +/- 31.53 micrograms/mg dry weight) (p > 0.05), but both differed significantly from the control specimens (1.55 +/- 0.87 micrograms/mg dry weight). In the second experiment, the immunological response to glutaraldehyde-treated bovine pericardium (glut tBP) and glycerol treated bovine pericardium (glyc tBP) implants were tested in vivo and in vitro. A Gore-Tex implant was used as a control. Sections of these materials were implanted to the abdominal muscle wall of Lewis rats, with each group composed of twelve animals. Lymphocytes and sera from the animals were isolated, and histological examination was performed at two or four weeks post-implantation. Collagen type 1 (calf skin) was used as antigen. Tritiated thymidine incorporation was used to measure lymphocyte response to antigen collagen type 1 (calf skin), and an Enzyme Linked Immunosorbent Assay (ELISA) was used to test antibodies. The results showed that lymphocytes from both the glut tBP and the glyc tBP groups responded to collagen type 1. The ELISA results showed that the glyc tBP group produced more antibodies than did the glut tBP group, with the difference being significant at a level of p < 0.02. Histology revealed that the glyc tBP had greater inflammatory changes and collagen degeneration than did the glut tBP. In the third experiment, sections of glut tBP and glyc tBP were implanted subcutaneously in two groups of ten weanling SD rats, and retrieved after 70 days. The results showed that glut tBP caused more calcification (197.04 +/- 83.56 micrograms/mg dry weight) than did the glyc tBP (6.74 +/- 0.55 microgram/mg dry weight), with the difference being significant at a level of p < 0.05. From these investigations it is concluded that tissue treatment prior to implantation was very important in determining the tendency of tissue to calcify, and that there was no obvious relationship between bioprosthetic calcification and immunogenicity.

Animals↗
PubMed1992

Cutaneous melanoma at Lawrence Livermore National Laboratory: comparison with rates in two San Francisco bay area counties.

During the period 1974 through 1985, employees at Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States) were diagnosed with cutaneous malignant melanoma at approximately three times the rate of the surrounding community. We investigated two explanations for this excess: the first explanation examined was that the recorded incidence of the neighboring community underestimates actual incidence. We estimated the amount of excess attributable to underreporting by using data from a survey conducted among San Francisco Bay Area clinicians and pathologists to determine previously unrecorded occurrences. We found that underreporting has negligible impact on melanoma incidence. The second explanation examined was that heightened medical awareness of the disease among LLNL employees and their physicians has led to greater detection. We found that LLNL melanomas are thinner than those from the surrounding community and that no excess was observed if we limited our attention to thicker, more invasive melanomas.

Adult↗
PubMed1992

Spontaneous host endothelial growth on bioprostheses. Influence of fixation.

BACKGROUND: Neither homografts nor bioprostheses have previously been seen to acquire a host endothelium. We previously reported a direct relation between aldehyde tanning and bioprosthesis calcification and the absence of calcification in the absence of aldehyde. METHODS AND RESULTS: Bovine pericardium was 1) treated with 0.625% glutaraldehyde and stored in 4% formaldehyde, 2) treated with 99.5% glycerol, and 3) treated with 99.5% glycerol and stored in formaldehyde (0.25-4%). The treated pericardium was used to construct stentless mitral valve prostheses (of a single pattern) that were implanted in weanling sheep. After the animals were killed, a strip of anterior cusp from annulus to papillary muscle was processed and examined by scanning electron microscopy for the presence of host endothelial growth. Avoidance of aldehyde allowed host endothelial growth in all cases (six of six), and pure aldehyde treatment inhibited growth in five of six animals. Exposure to aldehyde after glycerol treatment interfered with endothelialization significantly; after longer periods of implantation, however, endothelial growth occurred almost invariably in this group (12 of 13 implanted longer than 200 days). For this group, there was a statistically significant difference for duration of implantation between the valves that grew endothelium and those that did not (218.4 +/- 61.9 versus 128.5 +/- 65.4 days). CONCLUSIONS: Aldehyde treatment inhibits endothelial growth. With glycerol treatment, growth is uniformly present. Limited exposure to aldehydes after glycerol treatment inhibits endothelial growth, but this effect was ameliorated by prolonged implantation. The possibility of host endothelium-covered, noncalcifying bioprostheses is now real.

Animals↗
PubMed1991

Aldehyde tanning: the villain in bioprosthetic calcification.

Preservation of bioprosthetic valves may play a role in valvular calcification. Subcutaneous implants in rats were used to test the effect of different preservation solutions. Fifty male Sprague-Dawley rats were divided into five groups. Fresh bovine pericardium was treated in one of five ways: group A: 99.5% glycerol for 1 week; group B: as group A, then normal saline wash and 0.25% formaldehyde storage for 24 h; group C: as group A, then normal saline wash and 4% formaldehyde storage for 24 h; group D: as group A, then normal saline wash and 0.625% glutaraldehyde storage for 24 h; group E: 0.625% glutaraldehyde and 4% buffered formaldehyde storage. Treated bovine pericardium was cut into 1-cm2 pieces and washed for 30 min with normal saline before implantation. In each animal, three pieces were implanted in the subcutaneous tissue of the back. After 70 days, retrieved specimens were examined grossly, and X-ray densitometry, calcium analysis, and histological examinations were carried out. The results showed that glycerol-treated tissue (group A) had less calcification (calcium 6.92 +/- 4.46 micrograms/mg dry weight) than other groups: group B (calcium 323.12 + 63.56 micrograms/mg dry weight); group C (calcium 240.65 + 13.47 micrograms/mg dry weight); group D (calcium 232.29 + 13.01 micrograms/mg dry weight). These differences were markedly significant (p less than 0.0001). It appears that aldehydes play an important role in the calcification of bioprosthetic valves. Experience with glutaraldehyde- and glycerol-treated pericardium in valvular applications in sheep support these observations.

Animals↗
PubMed1991

Poisson regression with misclassified counts: application to cervical cancer.

"Errors in disease classification can give misleading inferences for covariate effects when the probability of error is itself related to the covariates. More accurate inferences are possible using supplemental data on both true and fallible disease counts at various covariate levels. We present a method for incorporating such supplemental data into disease rate regression and use it to show that, although observed intercountry differences in European cervical cancer mortality rates are exaggerated by errors in death certification, they are not completely explained by such errors." The data concern Belgium, England and Wales, France, and Italy.

Belgium↗
PubMed1983

Clinical factors predicting successful electrophysiologic-pharmacologic study in patients with ventricular tachycardia.

Data from 142 patients who had sustained ventricular tachycardia or ventricular fibrillation were analyzed to determine if clinical variables predict response to antiarrhythmic drugs at electrophysiologic study. Effective antiarrhythmic drugs were identified for 43 patients (30%). Ten of 25 variables analyzed were univariate predictors of drug response at the probability (p) level of less than 0.05. Stepwise logistic regression identified three variables independently predictive of drug response: fewer coronary arteries with 70% or greater stenosis (p less than 0.001), female sex (p less than 0.002) and fewer episodes of arrhythmia (p less than 0.03). A function incorporating these three variables was constructed to predict the probability of drug response, and ranges of the predictor function corresponding to high, intermediate and low probabilities of drug response were identified. Response rates in the high (greater than 50%), intermediate and low (less than 10%) probability ranges were 28 (58%) of 48, 10 (27%) of 37 and 5 (9%) of 57, respectively. Thus 40% of the patients who had a less than 10% likelihood of benefit from electrophysiologic-pharmacologic study were classified into the low probability range. When the predictor function was applied prospectively to 25 additional patients, response rates in the three probability ranges were 3 (50%) of 6, 1 (12%) of 8 and 0 (0%) of 11. These data show that analysis of clinical variables can be used to estimate the probability of benefit from electrophysiologic-pharmacologic study.

Anti-Arrhythmia Agents↗
PubMedDate not supplied

Extending myocardial viability during heart preservation with cyclosporine A.

BACKGROUND AND AIM OF STUDY: Hypothermic preservation (PRES) of donor hearts is limited to 12-14 hours for complete functional recovery after reperfusion. In a canine heterotopic heart transplant model, 50% to 60% functional recovery returned after 18 hours of PRES with University of Wisconsin (UW) solution. Concomitant with functional changes were marked increases in apoptotic cells at 2 (2.69%) and 6 (5.98%) hours of reperfusion with a concomitant decrease in lamin B1 (2% and 7.6%, respectively) with no evidence of necrotic cells. These results suggested that blockade of apoptosis may prolong myocardial viability during PRES and reperfusion. METHODS: Donor hearts were subjected to 18 and 24 hours of PRES (2 degrees C to 4 degrees C) with and without cyclosporine A (CyS) treatment (apoptosis blocker). CyS was given to the donor animal (10 mg/kg), in the PRES solution (10(-5) mol/L), slowly infused during the PRES period (1 mL/min), and also to the recipient animal (2.5 mg/kg). RESULTS: After 18 hours of PRES with CyS, function returned to 100% within 1 hour and stayed at this level throughout a 6-hour recovery period. Apoptotic myocytes were reduced (55%) after 18 hours PRES with CyS treatment, and 6-hour reperfusion lamin B1 was reduced to only 3.7%. Twenty-four hour PRES in UW resulted in no functional recovery. However, after CyS treatment, functional recovery returned to 100% after 4 hours of reperfusion. Adenosine triphosphate (ATP) and creatine phosphate (CP) concentrations were surprisingly the same with or without CyS treatment at 18 hours and lower with 24 hours. CONCLUSIONS: Use of CyS in the PRES solution prolongs myocardial viability during donor heart PRES. The mechanism of action may be associated with the mitochondrial permeability transition (MPT) pore via cyclophilin D binding.

Adenosine↗
PubMedDate not supplied

Fine needle aspiration diagnosis of malignant mixed tumor (carcinosarcoma) arising in pleomorphic adenoma of the salivary gland. A case report.

BACKGROUND: True malignant mixed tumor (carcinosarcoma), composed of carcinoma and sarcoma components, is rare in salivary gland neoplasms. Even rarer is a true malignant mixed tumor arising in the pleomorphic adenoma of the salivary gland. CASE: A 64-year-old male was admitted with left pharyngeal pain. Head and neck magnetic resonance imaging revealed a left parapharyngeal mass; fine needle aspiration (FNA) cytology through the oral cavity was performed. CONCLUSION: The aspirate presented a mixture of large, pleomorphic, vacuolated, single or multinucleated cells in a mucoid matrix and clusters of adenocarcinoma cells. Additionally, occasional benign glandular cells were noted. A cytologic diagnosis of malignant mixed tumor arising in the pleomorphic adenoma of the deep lobe of the parotid gland was made and confirmed by the surgically resected specimen.

Adenoma, Pleomorphic↗
PubMedDate not supplied

Comparison of intermittent warm and cold blood perfusion during hypothermic myocardial preservation on functional and metabolic recovery.

Numerous techniques are used to maintain intraoperative heart viability. The studies presented here evaluated heart function and metabolism after various periods of preservation up to 4 hours with intermittent warm and cold blood perfusion. Using a heterotopic heart model cooled to 10 degrees C and maintained for 1, 2, 3, and 4 hours, various preservation techniques were compared. Changes in myocardial metabolism were determined from substrate uptakes and biopsy samples of the left ventricular muscle for high-energy phosphates. Preservation techniques included: (1) sustained hypothermia, (2) 1 or 2 hours of sustained warm blood perfusion with fibrillation, (3) intermittent cold blood perfusion during 2, 3, and 4 hours of preservation, (4) intermittent warm blood perfusion during 2, 3, and 4 hours of preservation and (5) a control group (no preservation). Normothermic fibrillation had no effect on postpreservation functional or metabolic parameters. Sustained hypothermia reduced functional recovery proportional to the length of ischemia. The cold intermittent procedures maintained function and metabolism better than sustained hypothermia, while warm intermittent preservation maintained function and metabolism at control levels throughout the recovery period for all preservation techniques. Changes in ATP mirrored the functional changes. Creatine phosphate (CP) was markedly reduced during heart isolation and preservation and exceeded the control by 100% during reperfusion. For operative procedures of 2 hours or less, functional and metabolic recovery was not affected by the various preservation methods applied. Warm intermittent perfusion during hypothermic preservation offered the best protection for the myocardium. The warming cycles during hypothermia may provide some degree of preconditioning and protect the myocardium during reperfusion.

Animals↗