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Biomedical subjects

Y L Chang

Publications and source records attributed to Y L Chang.

At least 19 recordsLinked to original sources
PubMed1992

Prevalence of genital human papillomavirus infections in patients at a sexually transmitted diseases clinic.

The human papillomavirus was detected in cervicovaginal cells by the polymerase chain reaction in 14 of 37 (37.8%) patients attending a sexually transmitted disease (STD) clinic and in 6 of 43 healthy young women (14.0%) undergoing routine gynecologic examinations who served as controls. The results indicated that even the more malignant types of human papillomaviruses were not uncommon among the control group, and that the prevalence of human papillomavirus infection was significantly higher in STD clinic patients than in the control group. These findings confirm the suggestion that factors other than human papillomavirus infections may be involved in the pathogenesis of cervical cancer.

Ambulatory Care Facilities↗
PubMed1992

Possible transplacental transmission of human papillomaviruses.

OBJECTIVE: The objective of this study was to examine the possibility of intrauterine human papillomavirus infection of fetuses by transplacental transmission of human papillomavirus before delivery. STUDY DESIGN: Specimens of cervicovaginal cells and peripheral blood mononuclear cells were obtained from 52 consecutive pregnant women in the third trimester of pregnancy. Cord blood specimens were also obtained from the neonates born to these mothers. Presence of human papillomavirus types 16 and 18 deoxyribonucleic acid was analyzed by an in vitro enzymatic deoxyribonucleic acid amplification method. RESULTS: Human papillomavirus type 16 deoxyribonucleic acid was found in 6 (11.5%) cervicovaginal and in 9 (17.3%) peripheral blood mononuclear cell specimens. Seven cord blood specimens from neonates born to mothers who were positive for peripheral blood mononuclear cell human papillomavirus type 16 deoxyribonucleic acid were found to contain human papillomavirus type 16 deoxyribonucleic acid. One cervicovaginal and two peripheral blood mononuclear cell specimens contained human papillomavirus type 18 deoxyribonucleic acid, but none of the cord blood specimens contained human papillomavirus type 18 deoxyribonucleic acid. CONCLUSION: These results seem to suggest possible transplacental transmission of the virus and the potential association of such transmission with the status of human papillomavirus in peripheral blood mononuclear cells.

Base Sequence↗
PubMed1992

Intraneural anatomy of the median nerve provides "third web space" donor nerve graft.

To determine the feasibility of using the fascicular group to the third web space as a source of nerve graft material for bridging of median nerve gaps, a study of the intraneural anatomy of the median nerve was carried out in 23 fresh cadaver specimens. The pattern of plexus formation between the third web-space group and the remainder of the median nerve was determined. The average length of the third web-space fascicular group that could be separated from the median nerve proper prior to plexus intermingling was 24.5 cm. Cross-sectional areas of the graft and the remaining nerve were 4.43 mm2 and 13.76 mm2, respectively. The number of nerve fibers in the third web-space group was 4,847 and in the remaining median nerve, 13,486. Between February, 1989 and October, 1991, this technique has been used on 11 patients to provide donor nerve material for nerve gaps of 3 to 6 cm in the median nerve.

Adolescent↗
PubMed1992

Transcriptional regulation of precore and pregenomic RNAs of hepatitis B virus.

Hepatitis B virus (HBV) infection, either acute or chronic, has been one of the leading health problems in the world. To understand the HBV life cycle and disease process, we set out to study the regulation of viral gene expression. In this paper, we report the characterization of the HBV core promoter: two 3.5-kb transcripts, precore and pregenomic, are made from it. The latter is itself a template for viral genome replication and also encodes viral proteins essential for both viral replication and virion assembly. We identify a short sequence (from nucleotides [nt] 1744 to 1851, referred to as the basic core promoter [BCP]) that is sufficient to direct correct initiation of both precore and pregenomic messages. In addition, the two appear to be regulated in a coordinate manner. Sequences upstream of the BCP (from nt 1636 to 1744, referred to as the core upstream regulatory sequence [CURS]), have a strong stimulating effect on the BCP. Addition of the CURS to the BCP leads to a dramatic increase in both the transcription of two 3.5-kb messages and the production of 42-nm virions from transiently transfected hepatoma cells. The CURS stimulates the BCP in a position- and orientation-dependent manner. Therefore, it is unlikely that the effect is mediated through enhancer II, which has been localized to the same sequence. Deletion analysis of the CURS suggests that it contains multiple regulatory elements that control the BCP in an interactive manner. In accord with this hypothesis, the CURS is found to be bound with many distinct protein factors in footprinting experiments. Among these elements, box alpha (from nt 1646 to 1668) and box gamma delta (from nt 1671 to 1703) are two regulatory elements which individually stimulate promoter activity more than 100-fold.

Base Sequence↗
PubMed1991

Elevated levels of soluble interleukin 2 receptor and tumor necrosis factor in nasopharyngeal carcinoma.

Depressed cell-mediated immunity as a measure of the mitogenic response of mononuclear cells in patients with nasopharyngeal carcinoma is well documented, but the mechanism is still unclear. The enzyme-linked immunosorbent assay was used to measure soluble interleukin 2 receptor and tumor necrosis factor levels in 295 patients with nasopharyngeal carcinoma and 97 age-matched control subjects. Soluble interleukin 2 receptor levels in patients with nasopharyngeal carcinoma were elevated and correlated with clinical staging. Higher soluble interleukin 2 receptor levels were found in patients with bone metastasis but not in patients with intracranial involvement. The levels of tumor necrosis factor in nasopharyngeal carcinoma were higher than in control subjects but did not correlate with clinical staging. These data suggest that soluble interleukin 2 receptor levels might be more useful than soluble tumor necrosis factor levels that indicate tumor bulk. Soluble interleukin 2 receptor serves as a blocking factor that competes with interleukin 2 function, resulting in a decreased mitogenic response in patients with nasopharyngeal carcinoma. The usefulness of the levels of soluble interleukin 2 receptor to monitor the efficacy of treatment in patients with nasopharyngeal carcinoma with bone metastasis requires further study.

Adolescent↗
PubMed1991

Human papillomaviruses and small cell carcinoma of the uterine cervix.

The in vitro DNA amplification technique of polymerase chain reaction was used to evaluate the possible presence of human papillomavirus (HPV) in small cell carcinoma of the uterine cervix. None of the 12 cases examined contain detectable amounts of either HPV type 16, 18, 31, or 33 DNA. On the other hand, HPV types 16 and 18 DNA were found in 14 (93.3%) and 9 (60.0%) of 25 invasive cervical squamous carcinoma tissues. The results seem to suggest that these types of HPV are not present or are present in extremely small quantities in cervical small cell carcinoma. Such an absence of HPV DNA makes it unlikely that these types of HPV play any etiological role in the pathogenesis of cervical small cell carcinoma.

Adult↗
PubMed1991

Simultaneous bilateral forearm revascularization.

A successful simultaneous bilateral forearm revascularization was performed on a 17-year-old boy. Functional recovery of both forearms was evaluated 42 months after injury. The patient can use both hands for the activities of daily living. So far, he has been employed and has no significant psychological problems. Temporary intraluminal silicone shunts are extremely helpful for reducing ischemic damage to the injured limb. The sufficient skeletal shortening of the upper limb replantation is crucially important. The wounds must be managed by aggressive and repeated debridement. Accurate primary nerve repair is essential, and the early postoperative rehabilitation is also important to achieve a satisfactory functional return. The functional replanted or revascularized upper extremity is superior to an amputation or prosthesis, especially in the cases of bilateral upper extremity amputation or devascularization.

Adolescent↗
PubMed1991

Endolymphatic sac surgery for Meniére's disease. A cumulative study of twelve years' experience.

This paper analyzes a total of 861 endolymphatic-mastoid shunt procedures (ELS) during 12 years. The review of long-term results following surgery for patients with intractable Meniére's disease indicates that ELS often provides temporary remission of severe disabling symptoms. Overall results, according to AAOO criteria, showed long-term vertigo control in 71.90% of cases. Using AAO-HNS guidelines, vertigo was completely or substantially controlled in 85.89% of the cases. In addition, hearing gains were frequently sustained and hearing deterioration often prevented over the years. A positive dehydration test and/or fluctuating hearing indicate a greater likelihood of hearing improvement after surgery. Furthermore, these findings augment our previous studies that comparable results can be obtained regardless of method employed. Thus, ELS is still indicated as a primary choice of surgical treatment when surgery is mandatory. Finally, there seem to be chronological peaks of recurrence of symptoms at about 2 years and again at 6 or more years after ELS. This not only accentuates the efficacy of revision surgery, but opens new areas of investigation into the underlying etiology of this elusive disease.

Adolescent↗
PubMed1991

[Metastasis in oral squamous cell carcinoma].

A precise evaluation of the presence of metastasis is mandatory in the management of head and neck malignancies. Squamous cell carcinoma is the most common malignant tumor of the oral cavity, representing slightly more than 90% of all oral malignancies. The present study included 330 consecutive patients with oral squamous cell carcinoma seen at the Oral and Maxillofacial Surgery Division of the Department of Dentistry, Veterans General Hospital-Taipei from June 1975 to December 1990. Among these cases, the tongue (31.2%) was the most frequently involved site. According to AJCC staging system, 37.3% of the patients were at stage IV, the highest among stages of patients. The overall incidence of regional lymph node metastasis was 49.4%. The incidence of regional lymph node metastasis was significantly correlated with the location of the primary tumor, especially the low metastatic rate of palate and lip carcinoma (p less than 0.05). Distant metastases were detected in 14 (4.2%) cases. The rate of distant metastasis increased with the advance of staging (6.2% for stage III and IV, p less than 0.05). The lungs were the most common sites of distant metastasis. Due to the poor awareness and socio-economic condition of the patients, a majority of them presented with advanced diseases. The distant metastasis rate was low since all the patients were not kept followed up till death, nor was any autopsy study carried out.

Adult↗
PubMed1991

Surgical management of resistant idiopathic congenital clubfoot.

For neglected clubfeet or clubfeet resistant to conservative treatment, there is an increasing tendency towards early and tailored release. From November 1983 to November 1987, we operated on 37 children with 53 neglected or resistant clubfeet which included 23 with limited release and 30 with radical release. Their ages ranged from 4 months to 8 years with an average age of 1 year 5 months. Operative treatment was indicated if the clubfeet had been neglected or had shown no corrective change after 12 weeks of intensive plaster treatment. We used the Cincinnati incision for one-stage release. The average follow-up was 3.5 years (range 2-5.5 years). Evaluation criteria included physical, functional and roentgenographic findings. The results were good or excellent in 96% of the feet based on the modified Magone rating scale. There was no significant difference in the operation results between different age groups. Both the limited and the radical release groups had a high rate of satisfaction. The limited procedure only effectively improved the tibio-calcaneal angle to a significant degree (p less than 0.01), while the radical operation changed every angle significantly (p less than 0.01). Complications included calf muscle atrophy in 4 feet, overcorrection in 3 feet, undercorrection in 3 feet, superficial skin necrosis in one foot, pin tract infection in one foot and residual metatarsal adductus in one foot. In conclusion, neglected or resistant clubfeet can be treated by early and adequate release with a high rate of success. Complications can be avoided by a thorough understanding of their pathoanatomy and by a meticulous surgical approach and release.

Child↗
PubMed1990

A forearm free flap based on an occluded radial artery: its salvage and avoidance.

The salvage of a radial forearm free flap based on an occluded radial artery is reported. Circulation to the flap was restored by resection and reconstruction of the nonpatent arterial segment within the flap. A simple test is recommended for preoperative assessment of forearm radial artery patency in which proximal pulsation is felt after distal compression of the radial artery at the wrist.

Aged↗
PubMed1990

Early effects of cranial irradiation on hypothalamic pituitary function.

Hypothalamic pituitary functions were studied in 25 patients before and 6 months after cranial irradiation with or without radiosensitizing chemotherapy for nasopharyngeal carcinoma. The estimated average total dose was 5,000 cGy to the hypothalamus and pituitary gland. The radiosensitizing chemotherapy used was endoxan, 4900 +/- 873 mg and/or methotrexate 113 +/- 30 mg. All patients had normal pituitary function before radiotherapy. Six months after radiotherapy, there was a significant increase in baseline serum thyrotropin (TSH) and follicle-stimulating hormone (FSH) levels. The TSH response to thyrotropin-releasing hormone (TRH) was significantly increased, suggesting primary hypothyroidism due to neck irradiation. The peak serum TSH response to TRH became delayed in 21 patients, suggesting a defect in TRH release. In male patients who did not receive radiosensitizing chemotherapy, the FSH response to luteotropic hormone-releasing hormone (LHRH) increased while the luteinizing hormone (LH) response decreased. But in male patients who also received radiosensitizing chemotherapy, both the FSH and LH responses to LHRH increased. The adrenocorticotropic hormone (ACTH) response to ovine corticotropin-releasing hormone (CRH) did not change, while the integrated cortisol response increased. The growth hormone (GH) response to growth hormone-releasing hormone (GRH) did not change. The GH response to insulin tolerance test (ITT) increased and may be explained by the more severe hypoglycemia induced by the same dosage of insulin after radiotherapy or the recovery from the previous wasting caused by radiotherapy. There was no significant increase in serum prolactin. In conclusion, we demonstrated impairment of the hypothalamus-pituitary-endocrine gland axes as early as 6 months after cranial irradiation with or without chemotherapy.

Adolescent↗