Search PubMed⌕ Search

Biomedical subjects

K L Wang

Publications and source records attributed to K L Wang.

At least 19 recordsLinked to original sources
PubMed2001

Multiple globules in a cystic ovarian teratoma.

OBJECTIVE: To describe the characteristic imaging findings of multiple globules and globules-fluid level in a cystic ovarian teratoma. DESIGN: Descriptive case study. SETTING: Mackay Memorial Hospital and National Yang-Ming University, Taipei, Taiwan, Republic of China. PATIENT(S): A 20-year-old woman with left abdominal discomfort and a palpable mass on the left side of the distended abdomen. INTERVENTION(S): Surgical removal of a 10-cm cystic ovarian teratoma that contained chocolate-like fluid and multiple spheroid mobile globules consisting of yellowish sebaceous debris and fine hair shafts. MAIN OUTCOME MEASURE(S): Plain abdominal radiography, ultrasonography, and computed tomography (CT). RESULT(S): Plain abdominal radiography revealed no calcification in the mass. The first sonographic examination showed no movement by positional change of multiple rounded echogenic masses ranging from 0.5 cm to 2 cm in diameter, but the second CT examination done after the patient had spent some time lying down showed that the rounded masses arrayed in the upper portion of the cyst and displayed the characteristic level of globules-fluid. Thus, the differential diagnosis was multiple mobile globules in a cystic ovarian tumor. CONCLUSION(S): This case indicates that fatty masses need time to float upward in the fluid matrix of a cystic ovarian teratoma. This delayed effect should be considered when an ovarian cyst with multiple rounded echogenic masses is diagnosed by ultrasonography, CT, or magnetic resonance imaging.

Abdominal Pain↗
PubMed2001

Involvement of nervous system in maternally inherited diabetes and deafness (MIDD) with the A3243G mutation of mitochondrial DNA.

OBJECTIVES: The A3243G mutation of mitochondrial DNA (mtDNA) has been associated with maternally inherited diabetes and deafness (MIDD) in a number of reports; however, the involvement of the nervous system has rarely been mentioned, prompting this exploration of the manifestation of neurological disorders in MIDD cases. MATERIAL AND METHODS: We investigated four generations of a large Taiwanese family in which MIDD is manifest. We conducted a series of clinical examinations, including computed tomography (CT) and magnetic resonance imaging (MRI) of the head, brain 99mTc-HMPAO single photon emission computed tomography (SPECT), cognitive function tests, and nerve conduction velocity (NCV) studies. Blood levels of creatine kinase (CK) and lactate, pathology of muscle biopsy samples and proportions of mutant mtDNA in blood cells, hair follicles, muscle and skin were also analyzed. Mean follow-up period was 4 years. RESULTS: The patients exhibited the clinical features of diabetes mellitus including sensorineural hearing loss, short stature, and/or histories of spontaneous abortion. No stroke-like episodes were reported. Analysis for mtDNA revealed that the A3243G mutation existed in 11 members (6 symptomatic and 5 asymptomatic members) of this MIDD-prone family, with the proportion of mutant mtDNA ranging from 21% to 47% in leukocytes. Head CT revealed diffuse brain atrophy for all 6 (100%) patients examined and bilateral basal ganglia calcification in 4 of 6 (67%) patients. Brain 99mTc-HMPAO SPECT revealed diminished uptake in the bilateral parieto-occipital or occipital regions for all 6 tested patients, cognitive function for these patients was normal. Results of head CT and SPECT were normal in one asymptomatic member of the family. One muscle biopsy revealed abundant ragged-red fibers with modified Gomori-trichrome stain. Muscle-enzyme activity and serum-lactate levels were normal. CONCLUSION: We have demonstrated that a wide spectrum of sub clinical pathologies of the central nervous system and muscle are present for this MIDD-prone family, none of whom developed typical MELAS during the 4-year period of follow-up study.

Adolescent↗
PubMed2001

Microsatellite alterations in exfoliated cervical epithelia deoxyribonucleic acid as a marker for high-grade dysplasia.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of the use of deoxyribonucleic acid microsatellite alterations in cervical epithelia in the prediction of high-grade dysplasia and to compare it with a strategy based on human papillomavirus testing. STUDY DESIGN: Our prospective study subjects were from a cohort of 498 women with minimally abnormal Papanicolaou test results including atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesion who had documented repeated Papanicolaou and human papillomavirus tests. Of these, 52 eligible patients having conizations or hysterectomies as their histologic outcomes were subjected to tests of loss of heterozygosity on a panel of 5 microsatellites (D3S1110, THRB, D3S1228, D6S291, D3S1289) within the deoxyribonucleic acid of exfoliated cervical epithelia. These genetic alterations were analyzed through fluorescence polymerase chain reaction by comparison of allele ratios of exfoliated cells with those of normal control tissue. Predictive values for high-grade cervical dysplasia and cancer between this deoxyribonucleic acid marker and human papillomavirus status were compared. RESULTS: With the use of loss of heterozygosity in at least one locus for predicting high-grade cervical neoplastic lesion, the sensitivity, specificity, positive predictive value, and negative predictive value were 96.7%, 59.1%, 76.3%, and 92.9%, which were superior to those of the human papillomavirus test (80%, 59.1%, 72.7%, and 92.9%). As a triage for atypical squamous cells of undetermined significance, its sensitivity and negative predictive value were up to 100%. CONCLUSION: The promising results on determining microsatellite alteration in dysplastic lesions might imply that it is possible to detect the earliest changes by potential molecular markers with exfoliated cervical epithelial cells.

Adolescent↗
PubMed2001

Meniscus and synovial membrane: an electronmicroscopic study on rabbits.

Seven healthy mature rabbits were used to study both the surface morphology of the meniscus using both transmission electronmicroscopy (TEM) and scanning electronmicroscopy (SEM) and articular cartilage of the femoral condyle using SEM. Results showed that the membrane covering the meniscus was structurally the extension of synovial membrane of the knee joint capsule. Additionally, the presence of canal-like openings over the membranes surface to the meniscus was noted, which were absent over the articular cartilage surface.

Animals↗
PubMed2001

Anisotropic thermal conductivity of Ge quantum-dot and symmetrically strained Si/Ge superlattices.

We report the first experimental results on the temperature dependent in-plane and cross-plane thermal conductivities of a symmetrically strained Si/Ge superlattice and a Ge quantum-dot superlattice measured by the two-wire 3 omega method. The measured thermal conductivity values are highly anisotropic and are significantly reduced compared to the bulk thermal conductivity of the structures. The results can be explained by using heat transport models based on the Boltzmann transport equation with partially diffusive scattering of the phonons at the superlattice interfaces.

Anisotropy↗
PubMed1999

Ca2+/calmodulin stimulates GTP binding to the ras-related protein ral-A.

Ral-A is a Ras-related GTP-binding protein that has been suggested to be the downstream target of Ras proteins and is involved in the tyrosine kinase-mediated, Ras-dependent activation of phospholipase D. We reported recently that Ral-A purified from human erythrocyte membrane binds to calmodulin in a Ca2+-dependent manner at a calmodulin binding domain identified near its C-terminal region (Wang, K. L., Khan, M. T., and Roufogalis, B. D. (1997) J. Biol. Chem. 272, 16002-16009). In this study we show the enhancement of GTP binding to Ral-A by Ca2+/calmodulin. The stimulation up to 3-fold by calmodulin was Ca2+-dependent, with half-maximum activation occurring at 180 nM calmodulin and 80 nM free Ca2+ concentration. The present work supports a regulatory role of Ca2+/calmodulin for the activation of Ral-A and suggests a possible direct link between signal transduction pathways of Ca2+/calmodulin and Ral-A proteins.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1999

Androgen receptor gene mutations in 46,XY females with germ cell tumours.

We present clinical findings and molecular characterization in two patients previously diagnosed as 46,XY female gonadal dysgenesis with germ cell tumour. Both patients showed a female general phenotype with unambiguously female external genitalia and primary amenorrhoea compatible with complete androgen insensitivity syndrome. The first patient, at the age of 31 years, developed a dysgerminoma measuring 8 x 13 x 10 cm in one abdominal testis. Genetic analysis revealed a single nucleotide substitution on exon 4 in the hormone-binding domain of the androgen receptor (AR) gene, resulting in a change of codon 681 GAG (glutamic acid) to AAG (lysine). The second patient, at the age of 17 years, developed a dysgerminoma measuring 12 x 10 x 7 cm in one abdominal testis and gonadoblastoma in the other testis. Genetic analysis showed a point mutation on exon 3 in the DNA-binding domain of the AR gene resulting in a change of codon 607 CGA (arginine) to CAA (glutamine). Arg607-Gln and Arg608-Lys point mutations in the DNA-binding domain of the AR gene have been associated with male breast cancer in partial androgen insensitivity syndrome. A codon 607 mutation in the DNA-binding domain of the AR gene in our patient 2 is associated with early development of germ cell tumour. We suggest regular molecular genetic analysis of the AR gene in 46,XY females with germ cell tumour and androgen insensitivity syndrome to detect differences in the specific regions of AR gene involved in early progression toward oncogenesis of the dysgenetic gonads.

Adolescent↗
PubMed1998

Positive and negative autoregulation of REB1 transcription in Saccharomyces cerevisiae.

Reb1p is a DNA binding protein of Saccharomyces cerevisiae that has been implicated in the activation of transcription by polymerase (Pol) II, in the termination of transcription by Pol I, and in the organization of nucleosomes. Studies of the transcriptional control of the REB1 gene have led us to identify three Reb1p binding sites in the 5' region of the its gene, termed A, B, and C, at positions -110, -80, and +30 with respect to transcription initiation. In vitro, Reb1p binds to the three sites with the relative affinity of A >/= C > B. Kinetic parameters suggest that when both A and C sites are present on the same DNA molecule, the C site may recruit Reb1p for the A site. In vivo the A and B sites each contribute to the transcription activity of REB1 in roughly additive fashion. Mutation of both A and B sites abolishes transcription. On the other hand, the C site is a negative element, reducing transcription by 40%. In cells overexpressing Reb1p, the C site reduces transcription by more than 80%. This effect can be transposed to another transcription unit, demonstrating that the effect of Reb1p binding at the C site does not depend on interaction with upstream Reb1p molecules. Relocation of the C site to a position 105 bp downstream of the transcription initiation site abolishes its effect, suggesting that it does not act as a conventional attenuator of transcription. We conclude that binding of Reb1p at the C site hinders formation of the initiation complex. This arrangement of Reb1p binding sites provides a positive and negative mechanism to autoregulate the expression of REB1. Such an arrangement could serve to dampen the inevitable fluctuation in Rep1p levels caused by the intermittent presence of its mRNA within an individual cell.

Base Sequence↗
PubMed1997

Identification and characterization of a calmodulin-binding domain in Ral-A, a Ras-related GTP-binding protein purified from human erythrocyte membrane.

A 28-kDa protein (p28) has been purified from Triton X-100 extracts of human erythrocyte plasma membrane by calmodulin affinity chromatography. Based on internal peptide sequencing and its protein amino acid composition, this protein has been shown to be highly related, if not identical to, Ral-A, a Ras-related GTP-binding protein. This protein assignment is consistent with the findings that p28 binds [32P]GTP specifically and has low GTPase activity. In this study we describe the identification and characterization of a calmodulin-binding domain in Ral-A. The Ca2+-dependent interaction of p28 with calmodulin was first detected by a calmodulin affinity column. Gel overlay experiments of both p28 and recombinant Ral-A with biotinylated calmodulin provided strong evidence that Ral-A is a calmodulin-binding protein. A peptide of 18 residues (P18) with the sequence SKEKNGKKKRKSLAKRIR has been identified as a putative calmodulin-binding domain in Ral-A, because it comprises a basic/hydrophobic composition with the propensity to form an amphiphilic helix. P18 was synthesized, and its interaction with calmodulin by gel overlay was shown to be Ca2+-dependent. Circular dichroism analysis demonstrated that this interaction results in less alpha-helical content upon calmodulin complex formation. These results indicate that Ral-A is a calmodulin-binding protein, raising the possibility that it may be associated with Ca2+-dependent intracellular signaling pathways.

Amino Acid Sequence↗
PubMed1997

Cervical cancer in young women in Taiwan: prognosis is independent of papillomavirus or tumor cell type.

The objective of this study was to address the hypotheses that younger patients with cervical cancer have a uniquely worse clinical outcome and/or are more likely to have adverse tumor cell types or specific human papillomaviruses (HPV). Cases of stage Ib-IIa cervical cancer among women 35 years of age or younger (82) and over 35 (54) were analyzed and compared with respect to the following: (1) histologic type (squamous vs nonsquamous), (2) human papillomavirus (HPV) type via polymerase chain reaction, and (3) clinical parameters, including tumor size, nodal metastases, and recurrence/persistence. Patients 35 years of age or younger had a survival similar (71.2% vs 72.4%) to that of older women from the same institution. In the younger group, outcome was not correlated with the presence or absence of HPV or HPV type. Nonsquamous carcinomas, including adenocarcinoma and small cell carcinoma, were strongly associated with HPV18, were more prevalent in the younger group, and had a slightly higher risk of recurrence/persistence; however, these differences were not significant and 71% of the recurrences were squamous cell carcinomas. Thus, in young Taiwanese women with stage Ib-IIa cervical cancer, the majority of deaths cannot be attributed to a specific HPV type or unique tumor morphology.

Adult↗
PubMed1995

Intestinal malrotation and midgut volvulus: a 15-year review.

The records of 54 pediatric patients with symptomatic malrotation of the intestine seen over a 15-year period from 1978 to 1992 were reviewed. Bilious vomiting and bloody stools were the two most common clinical presentations in neonates, while bilious vomiting, recurrent abdominal pain and failure to thrive were the most common symptoms after the newborn period. Obscure symptoms, usually of appreciable duration, were common in many patients beyond infancy. Upper gastrointestinal radiologic examination is the preferred and more accurate method of diagnosing malrotation as it has greater sensitivity than barium enema study. Laparotomy showed 24 cases with midgut volvulus. The incidence of midgut volvulus in symptomatic malrotation was 42.1% in the neonatal period, and 50% beyond the neonatal period. The majority of patients were treated by Ladd's operation. Massive gangrene of the small bowel due to volvulus was noted in five neonatal cases. Three patients subsequently died of this complication. Four patients developed a bowel obstruction secondary to adhesions, which was relieved by enterolysis. This study reiterates that newborns with symptomatic malrotation require emergency laparotomy in order to prevent catastrophic massive bowel resection.

Adolescent↗
PubMed1994

Endoscopic injection sclerotherapy for esophageal variceal bleeding in children with extrahepatic portal vein obstruction.

From October 1989 to March 1994, 30 endoscopic injection sclerotherapies were performed in four consecutive female children who had extrahepatic portal vein obstruction complicated with esophageal variceal bleeding. Eradication of varices was achieved in three patients. However, bleeding occurred again in two of these patients due to esophageal varix recurrence. One patient, who discontinued sclerotherapy because of hemoptysis during treatment, also had 12 episodes of esophageal bleeding which were controlled by shunt therapy. In addition to hemoptysis, other complications were bleeding during sclerotherapy and fever. The sclerotherapy complication rate in this study was 17%. Our results suggest that endoscopic injection sclerotherapy is an effective and safe method for the prevention of variceal bleeding in children with extrahepatic portal vein obstruction. Long-term regular endoscopy follow-up and even repeated sclerotherapy are needed to prevent bleeding due to recurrence of esophageal varices.

Child↗
PubMed1994

Intussusception in infants and children: risk factors leading to surgical reduction.

Intussusception is commonly the etiology of intestinal obstruction in infants and children. To investigate demographic data, clinicopathologic features and therapeutic prognosis of patients with intussusception, we reviewed 361 intussusceptions in 333 patients over an 11-year period. Most patients were below two years of age and there was a male preponderance of 1.6:1. There was no seasonal difference between the number of cases. The clinical triad of vomiting, abdominal colicky pain and bloody stools was manifested in only one-third of our patients. Secondary intussusception contributed to 6.6% of cases and Meckel's diverticulum was the most common pathologic cause. Positive findings were recorded in 82% of 67 patients undergoing sonographic examination. Intussusception of the ileo-colic type was most frequently encountered. Most patients (79%) were diagnosed within 48 hours and almost all cases underwent primary barium enema reduction. The success rate was 45%. Laparotomy was performed in 207 patients (57%) refractory to enema reduction or with critical illness, and intestinal resection was required in 28 (14%). Long-standing duration of illness (> 24 hours), positive clinical triad, positive pathologic lead point, and radiologic finding of bowel obstruction were identified as risk factors leading patients to surgical reduction (p < 0.001). Postoperative complications and recurrent intussusception developed in some patients, and the overall mortality was 0.6%. The clinical characteristics of intussusception in children generally remained unchanged as compared to previous reports. Early identification of patients with risk factors for surgical treatment is important to decrease the need for intestinal resection.

Adolescent↗
PubMed1994

Anatomical findings of the vanishing testis.

Inguinal exploration of 62 clinically impalpable undescended testes reveals 40 (64%) instances of absent testis. Nine (22.5%) of the 40 explorations showed complete absence of the testes along with the epididymis and vas deferens, six (15%) were associated with only vas ending blindly, and the other 25 (67.5%) were associated with blind-ending vas deferens and blood vessels: the "vanishing testis syndrome." The anatomical findings of these vanishing testes showed the presence of a vas deferens and vessels lying side by side in the inguinal canal. In Addition, two patients with bilateral vanishing testis were found to be a normal 46 xy phenotypic male. Since testicular tissue is necessary in utero to stimulate external genital development, these findings, imply that testes vanished at some point following induction of masculinization, possibly as a result of an intrauterine vascular accident or testicular torsion. Also, according to the anatomical findings of vanishing testis, it gave us the signal to terminate the exploration when we found absent testis with a blind-ending vas plus vessels on one or both side in an operation for impalpable testis.

Child↗
PubMed1994

Management of yolk sac tumor of the testis in children.

Yolk sac tumor (YST) is the most common form of malignant testicular tumor in infancy and children. However, there is no general agreement on its treatment regimen due to its rare occurrence. From 1978 through 1990, 30 cases of YST of the testis were treated at Chang Gung Children's Hospital. Thirteen (43.3%) occurred in the right testis and 17 (56.7%) in the left. Age at operation ranged from six months to five years with a mean of 1.79 years. All patients received an orchidectomy as their initial treatment. Eighteen patients with stage I disease were treated by orchidectomy alone. Fourteen (77.8%) of them were free of disease, two patients who had recurrence with retroperitoneal metastasis were successfully treated with chemotherapy. The remaining two patients died of metastasis. Seven patients with stage II disease and five with stage III disease were treated with combination chemotherapy, irradiation or debulking operation following orchidectomy. Four stage II patients (57.1%) and one stage III patient (20%) showed no evidence of disease at the time of follow-up. It was concluded that for stage I disease, orchidectomy alone followed by strict monitoring of alpha- fetoprotein achieved an 89% disease-free survival rate. Retroperitoneal node dissection or routine chemotherapy added no benefit to survival. For stage II or III disease, chemotherapy or irradiation is needed to obtain a better outcome.

Child, Preschool↗