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Biomedical subjects

H Choi

Publications and source records attributed to H Choi.

At least 163 records · Page 9Linked to original sources
PubMed1992

[A patient with severe ventricular tachycardia who was saved by prolonged extracorporeal lung and heart assist].

A 47-y-o man had been suffering from cardiac failure due to refractory ventricular tachycardia (VT) after myocardial infarction. He underwent resection of the left ventricular aneurysm and cryocoagulation of the arrhythmogenic foci. On the 2nd post-operative day, VT often recurred in spite of repeated cardioversion and drug therapy, and threatened his life, even under IABP. Therefore, a veno-arterial bypass route was made and extracorporeal lung and heart assist, ECLHA, was started with a heparin bonded Maxima lung on the following day. Even under ECLHA, VT continued to recur. Cryocoagulation of the VT foci was tried again, without immediate success. A record high dose of beta-blockers, given under the circulatory support by ECLHA, stopped VT on the following day. The patient was weaned from the ECLHA circuit 12 days after the first operation, then from IABP on the 14th day. During the 10 day course of surgeries and ECLHA, the patient had almost 100 defibrillations. But for ECLHA, we may say that the patient couldn't have survived two open heart surgeries, administration of a great amount of beta-blockers, and repeated cardiac arrest without neurological sequelae.

Adult↗
PubMed1991

Thrombin and parathyroid hormone mobilize intracellular calcium in rat osteosarcoma cells by distinct pathways.

The mechanisms by which PTH and thrombin mobilize intracellular Ca2+ (Cai2+) were examined in UMR 106-H5 rat osteosarcoma cells. Bovine PTH-(1-34) (24 pM to 240 nM) produced a dose-dependent increase in Cai2+ (EC50, 3 nM), which returned to baseline within 75 sec. Human alpha-thrombin produced an increase in Cai2+ (ECmax, 10 U/ml) which was similar to that of PTH with respect to both magnitude and time course. Chelation of extracellular calcium with 5.0 mM EGTA did not alter the Cai2+ response to either PTH or thrombin. When added together at maximally effective concentrations, PTH and thrombin produced additive effects on Cai2+ in the presence and absence of EGTA. The additive effects of PTH and thrombin on Cai2+ were confirmed at the single cell level, using laser-based image analysis. Bradykinin (1 microM) produced a significant increase in Cai2+ in UMR 106-H5 cells which was of lesser magnitude than the peak 2- to 3-fold increase elicited by PTH or thrombin. Preexposure of cells to 10 U/ml thrombin for 2 min abolished the Cai2+ response to bradykinin, whereas preexposure to 240 nM PTH had no effect on the Cai2+ response to bradykinin. Thrombin elicited a rapid increase in the accumulation of 3H-labeled inositol phosphates (IP2 and IP3) in UMR 106-H5 cells, with increases in [3H]1,4,5-IP3 detectable as early as 15 sec after the addition of thrombin. Bradykinin increased [3H]IP production to a lesser extent than thrombin, whereas PTH neither increased [3H]IP accumulation nor potentiated the [3H]IP response to thrombin. The results suggest that thrombin and bradykinin mobilize Cai2+ from a shared IP3-responsive calcium pool, whereas PTH may use signals in addition to 1,4,5-IP3 to mobilize calcium from a distinct cellular calcium pool. Alternatively, specific calcium compartmentalization exists, and there is differential coupling of these agonists to the 1,4,5-IP3/Cai2+ pathway.

Animals↗
PubMed1991

Soft-tissue sarcoma: MR imaging vs sonography for detection of local recurrence after surgery.

To determine the value of MR and sonography in detecting local recurrences of soft-tissue sarcomas after surgery, 26 MR and sonographic studies performed in 21 patients were reviewed retrospectively. Recurrences were confirmed histologically in 12 (46%) of 26 studies. The MR images and sonograms were obtained within 1 month of each other. The findings were classified as recurrence, no recurrence, or indeterminate. Sonography was instrumental in guiding fine-needle aspiration biopsy of impalpable lesions. In two cases, the findings on sonography were indeterminate. In both of these cases, the sonograms had been obtained soon after surgery (at 2 and 4 months). The sensitivity and specificity in the detection of local recurrences were 83% and 93%, respectively, for MR and 100% and 79%, respectively, for sonography. These differences were not statistically significant. We conclude that MR and sonography appear to be equally useful in the detection of local recurrences of soft-tissue sarcomas, sonography can be used for routine follow-up and in guiding needle biopsies, sonography may be more difficult to interpret than MR during the early postoperative period, and MR should be used if sonography is inconclusive.

Adolescent↗
PubMed1990

Electrical stimulation of the medial amygdala facilitates gastric acid secretion in conscious rats.

One hundred and twenty-seven conscious rats prepared with chronic gastric fistula were studied to investigate the effect of stimulation of the medial amygdala on gastric acid secretion. Gastric acid output was significantly increased by electrical stimulation of the medial amygdala in normal rats and the increase in acid secretion was completely abolished by vagotomy. Vagotomized rats, with or without amygdaloid stimulation, showed comparable levels of gastric acid output which were significantly lower than in controls. These results indicate that the amygdala effect on gastric acid secretion is carried via the vagus nerve. Subcutaneous injections of high doses of histamine increased gastric acid secretion which was further increased by amygdaloid stimulation. Plasma levels of gastrin were not significantly changed by stimulation of the medial amygdala with or without vagotomy. From the above results, we concluded that in conscious rats the medial amygdala plays a significant role in stimulating gastric acid secretion, the vagus nerve is involved in this process, but it is not mediated by release of either histamine or gastrin.

Amygdala↗
PubMed1990

Terminal structure of a Densovirus implies a hairpin transfer replication which is similar to the model for AAV.

We cloned the complete sequence of Bombyx DNV (Ina isolate; Bm DNV-1) genome in a bacterial plasmid pUC 119 and determined the nucleotide sequences of both termini, resulting in elucidation of the nucleotide sequence of the complete genomic DNA of DNV. The complete sequence of the DNV DNA (5048 nucleotides) has inverted repeats of 225 nucleotides and the terminal 153 nucleotides are palindromic. The palindromes can fold back on themselves to form a hairpin structure but, unlike AAV, the small internal palindrome which forms a T-shaped conformation was not observed. End-label analysis demonstrated that the palindromic sequences at both termini can exist in either of two orientations (flip or flop) in virion DNA with different frequencies. These data suggest that the hairpin transfer model for AAV replication must be modified to explain the DNV replication. Additionally, a comparison study on the terminal structures of insect, human, and rodent parvoviruses allowed a prediction on the ancestral terminal structure of parvovirus genome.

Amino Acids↗
PubMed1990

The effect of experimental varicocele on the testis of adolescent rats.

Experimental varicocele was created by partial ligation of the left renal vein in rats 4, 7 and 12 weeks old to compare the effects of varicocele on the testis at different times of onset: prepuberty, adolescence and adulthood. We examined the testes at 4 and 8 weeks after creation of the varicocele. The experimental groups of rats 4 and 12 weeks old showed slight testicular changes compared to control groups at 4 and 8 weeks postoperatively. In the 7-week group left testicular weight was significantly decreased (1.03 +/- 0.31 gm.) compared to that of the control group (1.51 +/- 0.12 gm.) at 4 weeks. The seminiferous tubular diameter in the left testis also was significantly reduced (219 +/- 37 microns) compared to that of the control group (270 +/- 14 microns). Histological changes, such as degeneration of germinal epithelium, tubular atrophy, Sertoli cell hyperplasia and interstitial edema, were observed more frequently in the 7-week group. At 8 weeks these changes were less significant. Our results suggest that varicocele during adolescence has the most damaging effects on the testis in rats.

Animals↗
PubMed1990

Quantitative testicular biopsy in congenital and acquired genital obstruction.

To determine if congenital obstruction of the genital tract is associated with significant testicular histopathological conditions compared to acquired forms of obstruction we performed testicular biopsy in 8 vasectomized men and 5 men with vasal agenesis. Quantitative analysis of the seminiferous tubular and epithelial parameters demonstrated a statistically significant increase in tubular wall thickness in the vasectomized group. There was no significant difference among the groups with reference to the mean number of late spermatids per seminiferous tubules, mean number of Sertoli cells per seminiferous tubules, mean number of seminiferous tubules per field (100 times) or mean seminiferous tubular diameter. We conclude that despite a lifelong duration of obstruction, men with vasal agenesis demonstrate a more favorable testicular histological status compared to men after vasectomy. This finding may have therapeutic implications when considering assisted pregnancy techniques as a method of treatment of male genital tract atresia.

Adult↗
PubMed1990

Immunopathological response of C57BL/6 and C3H/HeN mice to Aspergillus fumigatus antigens.

C3H/HeN and C57BL/6 mice were exposed to culture filtrate (CF) and mycelial extracts (ME) of Aspergillus fumigatus (Af) intranasally. Animals received 6, 8 or 10 biweekly doses and were sacrificed 2 weeks after the last dose was administered. Specific antibodies against Af were detected in their sera by biotin-avidin-linked immunosorbent assay (BALISA). Antibodies against Af belonging to all isotypes showed an increase in both strains of mice. A progressive increase in IgG and IgA antibody isotypes against both CF and ME antigens was detected in C3H/HeN mice during the entire experimental period, whereas most antibody levels peaked after the 8th dose and remained steady or decreased slightly in the C57BL/6 strain. Lung lavage studies showed a relative decrease in the number of macrophages and an increase in the number of lymphocytes after the 6th and 8th instillation of Af antigens in both strains of mice. Histology of the lung demonstrated a progressive inflammatory reaction in C57BL/6 mice during the experimental period. On the other hand, the C3H/HeN mice showed a negligible inflammatory pulmonary reaction. The antibody responses and inflammatory changes detected in the lungs of mice exposed to Af antigens are comparable to allergic bronchopulmonary aspergillosis (ABPA) in humans and hence this model will be of value in understanding the disease mechanism in ABPA and related diseases.

Animals↗
PubMed1989

The influence of natural killer cells in neuroblastoma.

Human neuroblastoma (NRB) cell lines are markedly sensitive to natural killer (NK) cell lysis in vitro, but patients with NRBs have low or absent NK activity. This study evaluated the NK sensitivity of murine NRBs (C1300 and TBJ) in the regulation of NRB growth and determined the effects of recombinant (r) interferon gamma and recombinant interleukin 2 (rIL-2). Both basal (8% +/- 3% specific cytotoxicity) and induced (20% +/- 3%) NK lyses of C1300-NRB were observed. In vivo depletion of NK cells with anti-asialo GM-1 significantly enhanced growth of C1300-NRB and decreased survival. Treatment with r-interferon gamma or rIL-2 on days 1 through 3 after C1300-NRB inoculation significantly prolonged the mean tumor latency period, decreased the tumor growth rate, and enhanced in vitro NK killing of C1300-NRB and YAC-1. The effects of r-interferon gamma and IL-2 were abrogated by pretreatment with anti-asialo GM-1. These results demonstrated that NK cells form one important component of regulation of a murine NRB, but immunomodulation with potent lymphokines requires cooperation of more than one cell type.

Animals↗
PubMed1989

Effect of dopamine on electrical activity of isolated stomach muscle in cats.

The effect of dopamine on electrical activity (gastric slow wave) of the stomach was studied in isolated stomach muscle strips of 145 cats. The gastric slow wave was recorded by four monopolar electrodes (Ag-AgCl) in Krebs-Ringer solution (pH 7.4, temperature 36 +/- 0.5 degrees C) bubbled with 5% CO2 in O2. Dopamine induced concentration-dependent alterations in frequency and propagation of slow waves. Development of irregular propagation was significantly suppressed by domperidone pretreatment. The variation of dopamine-induced slow-wave frequency was significantly inhibited by domperidone and phentolamine but not by propranolol, hexamethonium, and tetrodotoxin. The study indicates that a dopamine receptor exists in the stomach and plays a role in the genesis of gastric electrical abnormality.

Animals↗
PubMed1989

Echogenicity of prostate cancer correlated with histologic grade and stromal fibrosis: endorectal US studies.

In this study an attempt was made to clarify some of the causes of the apparent differences in appearance on ultrasound (US) images of prostate cancer. These differences were correlated with histologic grade and the degree of stromal fibrosis present. Fifty-one cancers (diagnosed and evaluated by means of US-guided biopsy or evaluated by means of radical prostatectomy) were studied. There were 30 hypoechoic, ten echogenically mixed, six isoechoic, and five subtly hyperechoic cancers. The degree of stromal fibrosis was minimal in well-differentiated cancers and increased in poorly differentiated cancers. In addition, the more hypoechoic lesions were, in general, the better-differentiated cancers and had less fibrosis. There was a tendency for the isoechoic cancers and those with subtly hyperechoic areas to more often have poor cellular differentiation and a greater degree of stromal fibrosis, but considerable overlap among histologic types was seen.

Fibrosis↗
PubMed1989

A survey of externally recognizable genitourinary anomalies in Korean newborns. Korean Urological Association.

To estimate the incidence of externally recognizable genitourinary anomalies and associated anomalies in the newborns in Korea, retrospective and prospective studies have been performed. Thirty eight of 48 urology training hospitals participated in this nationwide survey. In this study we have included minor defects or variations in the anomaly to evaluate the incidence of the recognizable genitourinary conditions in the newborns. The incidence of genitourinary anomaly in 1,000 newborn delivery in a year was 11.0 in the prospective study and this figure is about three times higher than the retrospective study and is considered to be close to the true incidence. The incidence of genitourinary anomaly in 1,000 male newborn was 20.4. Hydrocele, cryptorchidism and hypospadias were most commonly observed. The incidence of hydrocele in 1,000 male newborn was 9.89 and the incidence of cryptorchidism was 7.26 and the incidence of hypospadias was 2.13. The incidence of associated anomaly in 100 genitourinary anomaly was 7.9. Congenital heart diseases and anorectal anomalies were commonly associated anomalies. In the newborns with genitourinary anomalies, premature infants account larger portion than is usually reported in total delivery.

Birth Weight↗
PubMed1988

Primary adenocarcinoma of the ileostomy after colectomy for ulcerative colitis.

A fifth case of adenocarcinoma arising at an ileostomy site many years after total colectomy for ulcerative colitis is reported with a review of the literature. The patient is a 79-year-old white man who presented with a bleeding, locally invasive exophytic mass at his ileostomy site 36 years after total colectomy for ulcerative colitis; he is the oldest patient, with the longest interval from creation of his ileostomy to diagnosis of adenocarcinoma. Careful gross and histopathologic examination of any mass arising at an ileostomy site is recommended. Early detection of such a slowly growing malignancy arising in a long-standing ileostomy may result in cure.

Adenocarcinoma, Papillary↗
PubMed1988

Malignant mixed mesodermal tumors of the ovary. A report of 13 cases.

The surgical pathology files at Thomas Jefferson University Hospital (TJUH) were reviewed for the period 1973-1984. Thirteen cases of primary ovarian malignant mixed mesodermal tumor (MMT) were found; however, material from only seven of these cases could be obtained for repeat review. No conclusions can be drawn regarding any impact on survival based on the histology. Treatment was highly varied reflecting the mix of physicians rendering treatment and the range of modalities used. Overall, survival was miserable. Six of the 13 patients (46.2%) survived 6 months or less, 10 of the 13 (76.9%) survived 12 months or less. No particular treatment modality seemed to offer enhanced survival unless aggressive cytoreductive surgery was performed. A plea is made for national cooperative groups to develop treatment protocols for this aggressive ovarian cancer.

Adult↗
PubMed1988

Implications of small, peripheral hypoechoic lesions in endorectal US of the prostate.

Endorectal ultrasound (US) can demonstrate small, nonpalpable, or subtly palpable lesions of the prostate. However, differentiation of benign from malignant processes has not always been possible. Because early diagnosis may have immense clinical implications, the possibility that endorectal US can be used to diagnose early prostate cancer has been suggested. The authors prospectively evaluated with endorectal US 80 small (less than 1.5 cm) peripherally oriented hypoechoic lesions in 79 patients with a normal or questionably abnormal digital rectal examination. In all patients at least two biopsies per lesion were performed. The transperineal sonographically guided biopsies were performed with both cytologic and core biopsy techniques. Seventeen of the 80 lesions (21.3%) were malignant. These findings suggest a low, but perhaps clinically significant, rate of diagnosis of small prostate cancers. While these data are interesting, they are insufficient to recommend use of endorectal US as a screening tool for prostate cancer.

Aged↗
PubMed1987

Urolithiasis in childhood: current management.

During the past 12 years, 62 children with urinary stones have been treated at the Children's Hospital of Philadelphia. The most common presenting symptoms were abdominal or flank pain (45%), recurrent or persistent pyuria (35%), and gross hematuria (21%). Twenty-two patients had associated congenital urologic anomalies. Infection-related struvite stones were most common and were found in 18 children, of whom 15 were found to have anatomic abnormalities. Eighteen of 28 children evaluated for a metabolic cause were found to have an abnormality, most frequently hypercalciuria. No predisposing factors could be found in 16 of the 62 patients. Forty-four (87%) children had upper urinary tract stones. Twelve of 15 bladder stones were in children with a neuropathic bladder and all were related to infection. Treatment was directed to the correction of anatomic and metabolic predisposing causes, as well as to removing the stones. Fifteen patients passed stones ranging in size from 2 to 6 mm. Forty-six surgical procedures were performed in 43 children. Pyelolithotomy and cystolithotomy were the most frequent procedures. There were three residual stones and five recurrences. Of the 29 operations for upper urinary stones reviewed, 17 might today be considered suitable for percutaneous nephrostolithotripsy or extracorporeal shockwave lithotripsy. Possible future stone management will be discussed in light of this analysis.

Adolescent↗