Biomedical subjects

C H Yang

Publications and source records attributed to C H Yang.

At least 163 records · Page 9Linked to original sources

PubMed1996

Oral tuberculosis.

Tuberculous lesions of the oral cavity have become so infrequent that it is virtually a forgotten disease entity and may pose a diagnostic problem. Fifteen patients with conditions that were histologically diagnosed as oral tuberculosis were reviewed. All were men ranging in age from 29 to 78 years. The most common clinical presentation was odynophagia with a duration from less than 1 week to several years. The most frequently affected sites were the tongue base and gingiva. The oral lesions took the form of an irregular ulceration or a discrete granular mass. Mandibular bone destruction was evident in two patients. Two patients had a fever, and four had cervical lymphadenopathy. Eight cases were clinically suspicious for malignancy before biopsy. Only four patients had a history of tuberculosis, but 14 of the 15 patients were later found to have active pulmonary tuberculosis. Acid-fast bacilli were demonstrated in all patients. Tuberculosis should be considered in patients with an inflamed ulcer lesion. A biopsy specimen for histologic study, acid-fast stains, and cultures should be obtained for confirmation and differential diagnosis with other conditions. If a tuberculous lesion is suspected, a chest radiograph is indicated to investigate the possibility of pulmonary involvement.

Adult↗

PubMed1996

Inhibition of cell-induced vitreous contraction by synthetic peptide derived from the collagen receptor binding sequence.

Cell-mediated tractional retinal detachment (TRD) is the end result of various intraocular proliferative disorders. Interactions between cells and extracellular matrix via cellular surface receptors, integrins, play an important role. Anti-adhesion therapy has been suggested as a promising way to treat the integrin-dependent pathological events. We tested three synthetic peptides, Gly-Arg-Gly-Asp-Ser (GRGDS), derived from the fibronectin receptor binding domain; Try-Ile-Gly-Ser-Arg (YIGSR), from the laminin receptor binding domain, and Ala-Asp-Gly-Glu-Ala (ADGEA), from the collagen receptor binding domain, to evaluate their inhibitory effect on cell-mediated matrix attachment and vitreous contraction in vitro, and on cell-induced TRD in rabbit eyes in vivo. Indirect immunofluorescent stain demonstrated both bovine retinal pigment epithelial (RPE) cells and rabbit dermal fibroblasts expressed the alpha 2 beta 1, alpha 5 beta 1 and alpha 6 beta 1 integrins, the collagen, fibronectin, and laminin receptors, respectively. GRGDS exhibited a broad spectrum of inhibitory activity on RPE cell attachment to extracellular matrices. YIGSR specifically inhibited RPE cell attachment to laminin, whereas ADGEA inhibited RPE cell attachment to collagen type I and IV. ADGEA inhibited RPE cell-induced vitreous contraction in a dose-dependent manner, whereas GRGDS and YIGSR had no effect. ADGEA (1250 micrograms/mL) delayed the development of TRD but did not prevent it. ADGEA was nontoxic to cells and retina, as demonstrated by cytotoxicity tests and histological examination. The synthetic peptide, ADGEA, and its analogs may be potential candidates for the treatment of cell-mediated collagenous contraction in the ocular tissues.

Animals↗

PubMed1996

Developmental synchrony of Ascogregarina taiwanensis (Apicomplexa: Lecudinidae) within Aedes albopictus (Diptera: Cuclicidae).

Development of Ascogregarina taiwanensis Lien & Levine was synchronized with its host, the Asian tiger mosquito, Aedes albopictus (Skuse). Trophozoites of the parasite migrate to the Malpighian tubules where the gamonts fuse to form gametocysts and later mature oocysts. In this study, we observed that water temperature, which alters the development time of mosquito larvae, also affected parasite development. A. taiwanensis developed in a shorter time at 29 degrees C, whereas at 14 degrees C, the development was extended to as long as 17 d. Few mature oocysts were produced at 29 degrees C, although gametocysts occasionally were found in the lumen of Malpighian tubules. In contrast, gametocysts did not develop at 14 degrees C unless pupation occurred. Stage transformation of the parasite was determined by the metamorphosis of the mosquito host. Gametocyst formation occurred earlier when infected larvae were injected with an appropriate concentration of 20-hydroxyecdysone, indicating this molting hormone was involved in regulating the synchronous development of A. taiwanensis in its mosquito host.

Aedes↗

PubMed1996

Increased intestinal contents viscosity reduces cholesterol absorption efficiency in hamsters fed hydroxypropyl methylcellulose.

This study was conducted to test the hypothesis that increased intestinal contents viscosity lowers plasma cholesterol concentrations by decreasing cholesterol absorption. Male Golden Syrian hamsters were fed for 4 wk diets containing 0.12% cholesterol, and either 4% cellulose or four different viscosity grades of hydroxypropyl methylcellulose (HPMC). Dietary HPMC confers viscosity in the small intestine but is resistant to fermentation. Cholesterol absorption efficiency was measured using the dual isotope ratio method, and plasma and liver cholesterol concentrations were determined enzymatically. Ex vivo viscosity of intestinal contents supernatants was measured using a Wells-Brookfield cone/plate viscometer, and the means of treatment groups ranged from 6 to 6532 mPa.s. Relative to dietary cellulose, all viscosity grades of HPMC resulted in significantly lower cholesterol absorption efficiency, lower plasma cholesterol concentration, and lower liver cholesteryl ester content. The logarithm of intestinal contents ex vivo viscosity was inversely correlated with dietary cholesterol absorption (r2 = 0.84, P = 0.028). Furthermore, dietary cholesterol absorption was positively correlated with plasma cholesterol concentration (r2 = 0.89, P = 0.017) and liver cholesteryl ester content (r2 = 0.96, P = 0.0031). Thus, the data suggest an independent role of intestinal contents viscosity in lowering plasma cholesterol concentration and liver cholesteryl ester content by reducing cholesterol absorption efficiency.

Animals↗

PubMed1996

Physical aggression and associated factors in probable Alzheimer disease.

Aggressive behavior is thought to be pervasive among and devastating to demented patients and their caregivers. This study investigated the prevalence of physical aggression in demented inpatients with Alzheimer disease (AD). Additionally, the characteristics and psychiatric symptoms that may be associated with aggression were tested. Forty-seven patients with probable AD were included in this study. Physical aggression was reported in 27 (57.4%) of the patients. These patients were older, had a later onset of dementia, and had a higher prevalence of misidentification, activity disturbances, and day/night disturbance. The relationship between these factors and physical aggression needs further clarification, which may help provide effective predictors and treatment of the aggressive behavior.

Aged↗

PubMed1996

Psychiatric consultations in obstetric inpatients.

OBJECTIVE: The purpose of this study was to investigate the psychiatric consultation condition in the obstetric ward with particular attention paid to the reasons for referral, psychiatric diagnoses and recommendations. METHODS: This study was conducted in a medical center with 73 obstetric beds. All psychiatric consultations of obstetric inpatients during a 3-year period were included in this study. Data were derived from clinical charts and consultation records that included demographic data, reasons for referral, psychiatric diagnoses and treatment recommendations. RESULTS: Within the 3-year period, 28 patients were referred for psychiatric consultation, or 0.3% of the 9,972 obstetric admissions. The obstetric group represented 0.7% of all the psychiatric consultations. The most common reason for the referral was anxiety. Many obstetric problems, medical histories and psychiatric histories were found in these 28 patients. The most common diagnoses were depression or dysthymia, and schizophrenia. The diagnosis of organic mental disorders was rarely found. The vast majority of the psychiatric consultants were likely to recommend medication and psychological intervention. CONCLUSION: Even though there is a low psychiatric consultation rate among the obstetric inpatients, it does not mean that the prevalence rate of mental disorders is low in the obstetric patients. Psychiatric problems may be neglected or happen after patients are discharged. Organic mental disorders were rarely found in the obstetric patients which suggested a different pattern of mental disorders in the obstetric patients compared to other patients. The stress during child delivery needs further study for it may exacerbate or predispose a mental disorder. It is suggested that collaboration between obstetric staff and the consultation-liaison psychiatrists may provide better care for pregnant women patients.

Affective Symptoms↗

PubMed1996

Identification of overlapping DNA-binding and centromere-targeting domains in the human kinetochore protein CENP-C.

The kinetochore in eukaryotes serves as the chromosomal site of attachment for microtubules of the mitotic spindle and directs the movements necessary for proper chromosome segregation. In mammalian cells, the kinetochore is a highly differentiated trilaminar structure situated at the surface of the centromeric heterochromatin. CENP-C is a basic, DNA-binding protein that localizes to the inner kinetochore plate, the region that abuts the heterochromatin. Microinjection experiments using antibodies specific for CENP-C have demonstrated that this protein is required for the assembly and/or stability of the kinetochore as well as for a timely transition through mitosis. From these observations, it has been suggested that CENP-C is a structural protein that is involved in the organization or the kinetochore. In this report, we wished to identify and map the functional domains of CENP-C. Analysis of CENP-C truncation mutants expressed in vivo demonstrated that CENP-C possesses an autonomous centromere-targeting domain situated at the central region of the CENP-C polypeptide. Similarly, in vitro assays revealed that a region of CENP-C with the ability to bind DNA is also located at the center of the CENP-C molecule, where it overlaps the centromere-targeting domain.

Amino Acid Sequence↗

PubMed1996

Salmonella infections: a retrospective 10-year analysis of 134 cases in a regional hospital in Taiwan.

A total of 134 cases of salmonella infections have been noted during the past 10 years in our hospital. Cases of non-typhoidal salmonellosis increased gradually but infections due to Salmonella typhi did not show the same trend. Gastroenteritis was the most prevalent diagnosis in patients below 1 year of age and non-typhoidal bacteraemia and localized infections were the most prevalent in patients over 50 years. Diabetes mellitus was an important underlying disease especially in patients with localized infections (86%). Travelling history played an important role in cases of enteric fever. The susceptibility pattern in non-typhoidal salmonella changed markedly over the study period; multiple drug resistance was noted. The susceptibility pattern of S. typhi showed no significant change. Seven deaths due to salmonella infections were noted (5.2%); all due to non-typhoidal salmonellosis, especially serogroup B. Age above 50 years, localized infection, infection with serogroup B and diabetes were poor prognostic factors.

Adolescent↗

PubMed1996

Inhibition of retinal pigment epithelial cell-induced tractional retinal detachment by disintegrins, a group of Arg-Gly-Asp-containing peptides from viper venom.

PURPOSE: Integrin-mediated extracellular matrix (ECM) attachment plays an important role in vitreous contraction of retinal pigment epithelial (RPE) cells. Disintegrins, a group of Arg-Gly-Asp (RGD)-containing peptides from viper venom, are potential anti-adhesion agents that interfere with integrin-ECM binding. This study was performed to determine whether disintegrins were effective in inhibiting RPE cell-induced matrix attachment in vitro and tractional retinal detachment in a rabbit model in vivo. METHODS: Two disintegrins, echistatin from viper Echis carinatus and flavoridin from Trimeresurus flavoviridis, were used. The expression of integrins on the surface of bovine and rabbit RPE cells was examined by indirect immunofluorescent stain with specific anti-integrin monoclonal antibodies. The inhibitory effect of disintegrins on RPE cell-mediated ECM attachment and vitreous contraction was evaluated with cell adhesion and vitreous contraction assays. In the in vivo model, rabbit eyes were injected intravitreously with either homologous rabbit RPE cells alone or together with disintegrins to induce tractional retinal detachment. The cytotoxic effect of disintegrins was examined with a cell proliferation assay using the alamar blue method. Retinal toxicity of disintegrins was evaluated with electroretinograms and histologic examination of the rabbit eyes. RESULTS: Bovine and rabbit RPE cells showed the positive staining for the integrins alpha 2 beta 1 and alpha 5 beta 1 on cell surface. Disintegrins, echistatin, and flavoridin inhibited RPE cell attachment to the ECM. The potency of disintegrins was 150 to 300 times higher than that of Gly-Arg-Gly-Asp-Ser (GRGDS) peptide. The disintegrins also inhibited RPE cell-induced vitreous contraction in a dose-dependent manner, whereas the GRGDS peptide had no effect. In the in vivo experiment, echistatin (50 microgram/ml) or flavoridin (80 microgram/ml) significantly inhibited RPE cell-induced tractional retinal detachment compared with the control group at week 2 (P< 0.05) and week 4 (P< 0.01) after surgery. Disintegrins were nontoxic to RPE cells and rabbit retina as evaluated by cytotoxicity tests, electroretinograms, and histologic examinations. CONCLUSIONS: The disintegrins were effective in inhibiting RPE cell attachment to the ECM and vitreous contraction in vitro. They also were effective in suppressing RPE cell-induced tractional retinal detachment in the rabbit eyes. They were nontoxic. Disintegrins and their analogs might be potential anti-adhesion therapeutic agents in the treatment of proliferative vitreoretinopathy.

Amino Acid Sequence↗

PubMed1996

Prevention of false results from preferential PCR amplification or VNTR alleles.

In forensic DNA typing, evidential samples generally involve limited amounts of DNA and so should be carefully utilized. Although polymerase chain reaction (PCR) of variable number of tandem repeats (VNTR) alleles is the prevailing method for forensic identification, the fidelity of amplification of heterozygous VNTR alleles with large disparities in length needs to be carefully examined. Reports in the literature and our own observations have demonstrated that PCR artifacts, bogus alleles and allelic drop-out of VNTRs, are related to the amount of genomic DNA, the number of amplification cycles and the length of alleles amplified. Two small (< 1 kb) hypervariable VNTRs (Apo B and HVR-Ig) markers used for forensic identification were chosen to study these relationships. The results revealed that PCR amplification for the heterozygous VNTR alleles with wide disparity in length (> 400 bp) easily produced the allelic drop-out problem and therefore, led to the false results; and the allelic fragment of PCR products was preferentially lost after only 2 cycles of overamplification. We also further established the relationship between the optimal number of amplification cycles and the amount of genomic DNA in the reaction mixture. In our routine forensic screening this relationship has been successfully applied to determine the optimal number of amplification cycles and to avoid the allelic drop-out problem and achieve fidelity of PCR-VNTR amplification. It has also been used to investigate forensic casework.

Alleles↗

PubMed1996

[Characteristics of dementia patients with hyperphagia].

Research into dementia has tended to concentrate on memory loss and other cognitive impairment, but attention has recently turned to the associated psychiatric symptoms and behavioral abnormalities. Among them, increases in the amount eaten or hyperphagia are not uncommon in dementia. This problem is of clinical importance since it not only jeopardizes patient's health, but also is a cause of caregiver burden. The aim of this study was to assess the prevalence of hyperphagia in dementia. Additionally, possible mechanisms underlying this problem were reviewed and related to the demographic data, cognitive function test, radiological findings and other psychiatric symptoms. Out of a sample of 91 demented inpatients, hyperphagia was present in 30.8%. Hyperphagia was significantly associated with delusion, misidentification, aggressive behavior, hoarding behavior and pica phenomena. But these patients did not show difference in cognitive function, radiological abnormalities, repetitive behavior and depressed mood when compared with other demented patients. The possible etiologies were discussed, including physiological and psychological factors. Hyperphagia is a complex phenomenon, better understanding of the underlying pathogenesis may highlight specific pharmacological or behavioral methods for the management this troublesome behavior.

Aged↗

PubMed1996

Psychotic symptoms in psychiatric inpatients with dementia of the Alzheimer and vascular types.

BACKGROUND: Demented patients often manifest psychotic symptoms including delusion, hallucination and misidentification. This report attempts to describe the frequencies and characteristics of such symptoms in psychiatric inpatients with dementia, and to identify the characteristics of dementia with and without psychotic symptoms. METHODS: The study included 78 demented patients who were consecutively admitted to the psychiatric ward. Their psychotic symptoms were obtained from semistructured interview and the assessment using BEHAVE AD. Delusion and hallucination were rated as "present" if the descriptions were consistent with the definition of Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R). Misidentification was defined individually. RESULTS: There were 54 patients with DAT and 24 patients with VD. The frequency of psychotic symptoms in DAT and VD was 71.8%. The frequency of delusion in DAT and VD was 59.0%, misidentification, 33.3% and hallucination, 25.6%. Demented patients with psychotic symptoms were older (p = 0.037) than those without psychotic symptoms. CONCLUSIONS: Psychotic symptoms are common in psychiatric inpatients with DAT and VD, the most common being delusional. Delusion of theft is the most common one. Demented patients with psychotic symptoms were older than those without.

Aged↗

PubMed1996

Participation of AT1 and AT2 receptors in the differential interaction between angiotensin II or III and alpha-2 adrenoceptors in the nucleus reticularis gigantocellularis in cardiovascular regulation and antinociception in rats.

We evaluated possible interactions between angiotensin II (AII) or angiotensin III (AIII) and the alpha-2 adrenoceptors of the nucleus reticularis gigantocellularis (NRGC) in the medulla oblongata that are involved in cardiovascular regulation and antinociception, as well as the angiotensin receptor subtypes involved, using Sprague-Dawley rats that were anesthetized with pentobarbital sodium. The efficacy of guanabenz, which acts on the alpha-2 adrenoceptors in the NRGC to elicit hypotension, bradycardia and antinociception, based on tail-flick responses to noxious thermal stimuli (50 degrees C), was used as our experimental index. Bilateral microinjection of AII or AIII into the NRGC, at equimolar doses (40 pmol) that did not alter base-line systemic arterial pressure, heart rate or tail-flick latency, significantly and site-specifically attenuated the cardiovascular suppression elicited by guanabenz (100 micrograms/kg i.v.). This attenuation was appreciably antagonized by coadministration of the AT2 receptor antagonist PD-123319 (1.6 nmol). Concomitant examination of tail-flick responses revealed discernible inhibition by AII (40 pmol), but potentiation by AIII (40 pmol), of guanabenz-induced antinociception. These differential modulating effects of AII and AIII were, however, antagonized by comicroinjection of losartan (1.6 nmol) into the bilateral NRGC. Our results suggest that both AII and AIII produced a reduction, via AT2 receptors, of the activity of alpha-2 adrenoceptors in the NRGC that are involved in central cardiovascular regulation. On the other hand, antinociception induced by activation of alpha-2 adrenoceptors in the NRGC was suppressed by AII and potentiated by AIII, although AT1 receptors may play a major role in both interactions.

Analgesia↗

PubMed1996

Clinical spectrum of Pseudomonas putida infection.

The clinical and microbiologic characteristics of 55 cases of Pseudomonas putida infection in 53 patients in a medical center in Taiwan from April 1988 to March 1993 are reported. P. putida was cultured in the decreasing order of frequency from urine (24 isolates), sputum (12), blood (10), wound discharge (3), peritoneal fluid (3), cerebrospinal fluid (2) and umbilical swab (1). Of the adult patients, 23% (12/53) were considered to be contaminated or colonized with P. putida. Of the 41 patients with manifest disease. 17 (41%) had urinary tract infections, 10 (24%) had pneumonia, 8 (19%) had septicemia, 3 (7%) had wound infections, 2 (5%) had meningitis and 1 (2%) had peritonitis. Of these, 55% were nosocomial infections. The case fatality rate was 29% (12/41). There was no significant correlation between patient mortality and the type of disease caused by the bacterium. Results of in vitro susceptibility tests suggested that imipenem and ceftazidime were more effective than other antimicrobials. This study indicates that the clinical spectrum of diseases caused by P. putida is broader and the incidence of true infection is higher than previously expected, especially among hospitalized patients who undergo invasive procedures such as placement of intravascular devices, urinary catheterization and intubation.

Adolescent↗

PubMed1996

Evaluation of laser and radiofrequency induced dorsal root entry zone lesion for pain control in rats.

BACKGROUND: Dorsal root entry zone (DREZ) lesions have been believed to be effective for control of intractable pain. These lesions are usually made using radiofrequency (RF) technique. Theoretically, laser can provide very fast, precise, reproducible and easy control of photothermal effect, possibly achieving better pain control than RF. The objective here was to learn more about the effect of pain control among the RF, carbon dioxide (CO2) laser and potassium titanyl phosphate (KTP) laser in rats. METHODS: The adult rat was anesthetized and the dorsal spinal cord from C5 to T1 was exposed under a microscope. The DREZ lesions were created in each group of eight including sham, RF thermocoagulation, CO2 laser and KTP laser. The latency of pain withdrawal in the fore-paw by a hot-plate test was recorded before the DREZ lesions and three weeks afterward. RESULTS: The data showed that RF, CO2 and KTP laser could significantly reduce pain in rats (p < 0.05, one-way ANOVA and Dunnett's test). Latencies of pain withdrawal in the fore-paw by the hot-plate test before, and three weeks after, DREZ lesions were 13.9 +/- 1.4 sec and 65.2 +/- 4.9 sec in the RF group, 15.9 +/- 1.4 sec and 59.0 +/- 5.9 sec in the CO2 laser group, and 14.1 +/- 0.9 sec and 64.8 +/- 5.7 sec in the KTP group, respectively. CONCLUSIONS: The density of opioid receptor in DREZ lesions cord showed no significant change three weeks after operation in the sham and CO2 laser groups. It was concluded that DREZ lesions caused by RF, CO2 laser and KTP laser can achieve pain control significantly in the rats. The effect of KTP laser was close to RF, followed by CO2 laser.

Animals↗

PubMed1995

Ligand-directed immunoaffinity purification and properties of the one-carbon, reduced folate transporter. Interspecies immuno-cross-reactivity and expression of the native transporter in murine and human tumor cells and their transport-altered variants.

Almost complete purification (> 95%) of the 46-kDa murine, one-carbon, reduced folate transporter (RFT) at a recovery of 20% was obtained by ligand-directed immunoaffinity fractionation from transporter overproducing L1210/R83 cells. These cells were labeled with the N-hydroxysuccinimide ester of [3H]aminopterin (AMT), the isolated plasma membrane alkaline washed to remove nonintegral membrane proteins, detergent-solubilized, and RFT-separated on an anti-AMT antibody-protein G-Sepharose column followed by preparative SDS-polyacrylamide gel electrophoresis. Anti-RFT antibody, subsequently derived, differentially blotted (L1210/R83 >> L1210/0) a 46-kDa protein during SDS-polyacrylamide gel electrophoresis of plasma membrane from L1210/R83 and L1210 cells and in L1210/R83 cells after trichloroacetic acid precipitation. In contrast to that reported for human tumor cells, glycosidase treatment of RFT revealed no common N- or O-linked core oligosaccharides associated with this protein. The same 46-kDa protein at different relative levels was revealed in a Western blot of plasma membrane from other murine tumors. Blotting of plasma membrane from methotrexate resistant, transport defective L1210 cell variants exhibited wild-type levels of a less electrophoretically mobile RFT or greater levels of the same 46-kDa RFT which could not be affinity labeled with N-hydroxysuccinimide-[3H]AMT. The same antibody differentially blotted a 83-kDa plasma membrane protein from human HL-60 and CCRF-CEM cells with different levels of reduced folate transport and affinity labeling of RFT, verifying the conserved nature of this protein consistent with earlier functional studies.

Aminopterin↗

PubMed1995

Presynaptic D2 dopaminergic receptors mediate inhibition of excitatory synaptic transmission in rat neostriatum.

The effect of dopamine (DA) on excitatory synaptic transmission was studied in rat neostriatal neurons using intracellular- and whole-cell voltage clamp-recording methods. Depolarizing excitatory postsynaptic potentials (EPSPs) were evoked by cortical stimulation. Superfusion of DA (0.01-10 microM) reversibly decreases EPSP in a concentration-dependent manner and with a estimated IC50 of 0.3 microM. In addition, the inhibitory effect induced by DA at a low concentration (0.1 microM) was antagonized by sulpiride (1-10 nM), a selective D2 dopaminergic receptor antagonist. However, D1 dopaminergic receptor antagonist SKF-83566 (1-5 microM) did not affect the blocking effect by DA 0.1 microM. Based on these findings, we conclude that DA at a low concentration (< or = 0.1 microM) reduced the excitatory response of neostriatal neurons following cortical stimulation via the activation of D2, but not D1 dopaminergic receptors, located on the terminals of corticostriatal neurons.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1995

Overexpression or mutation of the p53 tumor suppressor gene does not occur in malignant ovarian germ cell tumors.

BACKGROUND: The p53 tumor suppressor gene has been well studied in epithelial ovarian cancers. However, little is known of the expression of this gene in ovarian germ cell tumors. The authors attempted to investigate whether p53 alterations occurred in this group of tumors. METHODS: Twenty-two patients with malignant ovarian germ cell tumors were included in this study. Immunohistochemical staining for p53 was performed on paraffin embedded tissue of each case. Single-strand conformation polymorphism analysis of exons 4-9 of the p53 gene was performed on 9 of the 22 tumors where genomic DNAs were obtained from the frozen tissue samples. Three tumors that revealed focal p53 positivity by immunostaining were studied further with direct DNA sequencing. RESULTS: Overexpression of p53 was not observed in all of the 22 ovarian germ cell tumors; only 3 were found to have nuclear staining in a small fraction of the malignant cells (< 5% in 1 immature teratoma, 5-10% in 2 yolk-sac tumors). Among the nine frozen tumors subjected to single-strand conformation polymorphism analysis, none revealed p53 mutation in exons 4-9. There was no p53 mutation detected by DNA sequencing of the three tumors with focal immunoreactivity. CONCLUSIONS: Alterations of the p53 tumor suppressor gene may not be associated with the pathogenesis of ovarian germ cell tumors. Instead, genetic changes such as inactivation of other tumor suppressor genes and/or activation of some protooncogenes need to be studied to determine the genetic mechanisms of the tumor development.

Adolescent↗