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Biomedical subjects

S K Lau

Publications and source records attributed to S K Lau.

At least 37 records · Page 2Linked to original sources
PubMed1992

Effect of irradiation on middle ear effusion due to nasopharyngeal carcinoma.

The management of middle ear effusion by myringotomy and insertion of ventilation tubes in 75 adult patients was evaluated. In Group 1 the middle ear effusion was not related to nasopharyngeal carcinoma. The patients with nasopharyngeal carcinoma were subdivided into pre and post-radiotherapy groups (Group 2 and Group 3) according to the time of insertion of the ventilation tubes. Myringotomy and insertion of ventilation tubes achieved significant hearing gain in all three groups. The pre and post-radiotherapy groups had a higher post-operative infection rate than Group 1 (P greater than 0.01). The duration of a persistent tympanic membrane defect in the post-radiotherapy group was significantly longer than Group 1 (P = 0.03). The post-radiotherapy group had more perforations than Group 1 (P = 0.02). A total of 28% of ears in the post-radiotherapy group were discharging at the last visit. In view of the higher complication rate in the post-radiotherapy group, the role of myringotomy and insertion of ventilation tube is reassessed.

Adolescent↗
PubMed1991

Combined use of fine-needle aspiration cytologic examination and tuberculin skin test in the diagnosis of cervical tuberculous lymphadenitis. A prospective study.

A prospective study to evaluate the efficacy of combined use of fine-needle aspiration (FNA) cytologic examination and Mantoux test in the diagnosis of cervical tuberculous lymphadenitis was carried out. Tuberculin reactions were determined in 59 control subjects. Preoperative FNA cytologic examinations and Mantoux tests were performed on 74 patients with cervical lymphadenopathy. The lymph nodes were then excised and examined histologically and cultured for mycobacteria. Forty-eight, 22, and 4 patients had histologically confirmed tuberculous, non-specific, and malignant lymphadenopathy. Fine-needle aspiration cytologic examination alone could detect cervical tuberculous lymphadenitis in 37 patients (77%). The predictive value of a strong tuberculin reaction for mycobacterial infection was 100%. The combined use of a Mantoux test and FNA cytologic examination was able to diagnose 43 (90%) of 48 cases of tuberculous lymphadenitis cervical preoperatively. Combined use of FNA cytologic examination and Mantoux test was efficient in the diagnosis of tuberculous lymphadenitis.

Adolescent↗
PubMed1991

Source of tubercle bacilli in cervical lymph nodes: a prospective study.

A prospective study searching for associated mycobacterial infection of the upper aerodigestive tract in patients with cervical tuberculous lymphadenitis (TBLN) was carried out. One hundred and thirteen patients with a clinical suspicion of cervical TBLN were included. All patients had a physical examination of the upper aerodigestive tract. Routine endoscopy and biopsy of the nasopharynx were performed. All of them had surgery to the cervical lymph node. Seventy-five patients had histologically confirmed cervical TBLN. Culture of the lymph node specimen showed Mycobacterium tuberculosis in 68 (90 per cent). In 45 (60 per cent) patients with cervical TBLN the primary foci of infection could not be found. Twenty-nine (39 per cent) had radiographic evidence of active or healed pulmonary tuberculosis. Sputum culture from two patients showed Mycobacterium tuberculosis. Five patients (six per cent) had tuberculous nasopharyngitis. In one of them (one per cent) the tuberculous nasopharyngitis was primary as no other evidence of mycobacterial infection was found. In the present study, mycobacterial infection of other parts of the upper aerodigestive tract was not found.

Adolescent↗
PubMed1991

The cytological diagnosis of nasopharyngeal carcinoma using a silk swab stick.

A prospective study was carried out to investigate the efficacy of exfoliative cytology for the diagnosis of nasopharyngeal carcinoma. Exfoliated nasopharyngeal cells were collected from patients with a clinical suspicion of carcinoma by scraping the nasopharyngeal mucosa with a piece of silk wrapped around one end of a wooden stick. Ninety-eight patients were investigated in this manner, and the results of cytological investigation compared with the histological findings. The sensitivity of cytological investigation was 71% and the overall accuracy was 86%. The combined use of cytology and serology as a method of screening for nasopharyngeal carcinomas is discussed.

Adolescent↗
PubMed1991

Radical neck dissection in nasopharyngeal carcinoma.

We report a series of 37 patients who had radical neck dissection for residual or recurrent lymph node metastasis from nasopharyngeal carcinoma after radiotherapy. The operation was performed despite high doses of pre-operative radiotherapy. There was no operative mortality and the morbidity was 13% (2 prolonged chylous drainage, 3 sloughing of neck flap). The risk of sloughing of neck flap was significantly related to previous lymph node biopsy, which should be avoided if at all possible. In 35% of patients, the lymph node was densely adherent to neighbouring structures. In the 28 patients who had single lymph node clinically, 29% had multiple neck node involvement noted during operation; another 14% were documented only on histological examination. Radical neck dissection rather than excision alone is justified for the clinically solitary lymph node.

Adult↗
PubMed1990

Efficacy of fine-needle aspiration and sampling of lymph nodes in 1,484 Chinese patients.

A retrospective study of 1,855 fine-needle aspirations of the lymph node (LN) from 1,484 Chinese patients in Queen Mary Hospital over a period of 11.5 yr (January 1, 1976, to June 30, 1987) was reviewed and analyzed. Positive cytologic results diagnosed malignancies in 49.3%. Sensitivity and specificity of cytology reached 95% and 96.5%, respectively. The order of frequency of the metastatic tumors according to primary sites was analyzed. The most common metastatic carcinomas in various groups of LNs were nasopharyngeal carcinoma in the cervical LN, breast carcinoma in the axillary LN, and cervical carcinoma in both the groin and pelvic LNs. Tuberculosis (TB) is an important differential diagnosis; FNAC showed a sensitivity of 76.9% in the detection of TB lymphadenopathy.

Adolescent↗
PubMed1990

Efficacy of radical neck dissection for the control of cervical metastasis after radiotherapy for nasopharyngeal carcinoma.

Fifty-one patients who had persistent or recurrent neck disease from nasopharyngeal carcinoma after radiotherapy underwent radical neck dissection. The follow-up period ranged from 0.5 to 9 years (median: 2 years). Multiple cervical lymph node involvement was present in 51% of the patients (26 of 51). Malignant cells were detected in 88% of the resected specimens (45 of 51). The clinical sign of fixation of lymph node is the only factor that affects the successful control of neck disease (p = 0.04). Extracapsular extension of the nodal disease was present, and 35% of the lymph nodes were adherent to surrounding structures at operation (18 of 51). There was one hospital mortality and the overall morbidity was minimal. The actuarial survival at 5 years was 38%, and the probability of control of neck disease was 66%. Radical neck dissection is effective in controlling post-irradiation cervical metastasis from nasopharyngeal carcinoma.

Adult↗
PubMed1990

Efficacy of fine needle aspiration cytology in the diagnosis of tuberculous cervical lymphadenopathy.

The results of a consecutive series of 1,349 fine needle aspiration (FNA) biopsies from the head and neck region of 1,193 patients has been reviewed in order to evaluate the efficacy of this method in the diagnosis of tuberculous lymphadenopathy (TBLN). Of the 108 patients whose fine needle aspiration cytology (FNAC) showed granulomatous changes, 68 had subsequent surgery and histological confirmation of the cytological appearance. Sixty-three had TBLN, thus the specificity of FNAC was 93 per cent in diagnosing tuberculous related granulomatous lymphadenopathy. One false positive FNAC was reported histologically to be metastatic mucoepidermal carcinoma. Of the 1,193 patients, 90 patients had subsequently TBLN confirmed histologically. Of these 90 patients, FNA from 69 showed granulomatous changes or acid fast bacilli (AFB), thus the sensitivity of FNAC in detecting tuberculous lymphadenopathy was 77 per cent. Fifty-two cytological smears were stained for acid fast bacilli. Nineteen (37 per cent) contained AFB. It is evident from this review that FNAC is an efficient way to detect cervical tuberculous lymphadenopathy.

Biopsy, Needle↗
PubMed1990

A clinical comparison of budesonide nasal aerosol, terfenadine and a combined therapy of budesonide and oxymetazoline in adult patients with perennial rhinitis.

The efficacy of budesonide, terfenadine and a combination of budesonide and oxymetazoline in the treatment of perennial rhinitis was evaluated by a double blind, parallel group study. Adult patients with perennial rhinitis were randomized into three groups. Group 1 patients received budesonide nasal aerosol 400 micrograms/day for 21 days and oxymetazoline nasal drops for the first three days. Group 2 and 3 patients received budesonide 400 micrograms/day and terfenadne tablet 60 mg twice/day respectively. Nasal symptoms were assessed by the patients before and daily during the treatment period using a simple scoring system. One hundred and forty-two patients were recruited and 130 completed the study. Budesonide, but not terfenadine, significantly reduced all nasal symptoms from baseline (p less than 0.05). Terfenadine could significantly relieve the nasal blockage (p less than 0.05) more than other nasal symptoms. Budesonide with or without oxymetazoline nasal drops provided a better control of nasal symptoms than terfenadine (p less than 0.05). Budesonide with oxymetazoline for the first three days showed a faster relief of nasal blockage than budesonide alone (p less than 0.05). Mild and transient adverse effects were encountered in all three groups. It is concluded that nasal symptoms of perennial rhinitis are more adequately controlled by budesonide than by terfenadine.

Adolescent↗
PubMed1988

Brainstem auditory evoked potentials after irradiation of nasopharyngeal carcinoma--report on two cases with myelopathy of the brainstem.

Brainstem auditory evoked potentials (BAEP) were recorded in two patients with nasopharyngeal carcinoma (NPC) irradiated 14 and three years ago respectively and compared with 15 healthy controls. The patients had features of post-irradiation myelopathy of the brainstem with reduced gag reflex, unilateral vocal cord paralysis and fasciculation of the tongue. The first patient had a blind left eye. The second patient had quadriparesis. All ears revealed post-irradiation otitis media changes and mixed deafness. BAEP was not recognizable in the left ear of the first patient and was normal in the left ear of the second patient. Simultaneous electrocochleogram and BAEP were recorded from the right ear of the first case. The wave I-V latency interval were prolonged in both right ears. In the absence of local recurrence and brain secondaries, these BAEP changes are attributed to the post-irradiation myelopathy of brainstem.

Brain Stem↗
PubMed1988

Fine needle aspiration biopsy of tuberculous cervical lymphadenopathy.

Fine needle aspiration biopsies of 42 histologically confirmed tuberculous cervical lesions were studied. Thirty-four patients had subsequent excision of cervical lymph nodes and eight had incision and drainage of cervical abscesses. All aspirates except two (which were inadequate) were satisfactory for diagnosis and contained inflammatory cells. Twenty-seven smears revealed cells typical of granulomatous lymphadenopathy, that is, epithelioid and multinucleated giant cells. Of all aspirates, 17 smears had bacteriological staining by Ziehl-Nielsen technique, nine of which (53%) were positive for acid-fast bacilli. An aspiration biopsy diagnosis of granulomatous or tuberculous cervical lymphadenopathy was made in 30 patients (71%). In regions where mycobacterial infection is common, the presence of granulomatous changes in lymph node aspirates is highly suggestive of tuberculosis. When the aspirates contain purulent material or when tuberculosis is suspected, staining and culture for mycobacteria should be performed. FNA biopsy is a sensitive, specific and cost-effective way to diagnose tuberculous cervical lymphadenopathy and is recommended.

Adolescent↗
PubMed1988

Effects of gonadal steroids on somatotroph function in the rat: analysis by the reverse hemolytic plaque assay.

The mechanism by which gonadal steroids modulate GH secretion is not known. We have used the reverse hemolytic plaque assay to examine whether gonadal steroid-induced modulation of GH secretion is effected by changes in the population of somatotrophs and/or alterations in their secretory properties. Two groups of Sprague-Dawley rats were studied: group 1 (n = 6) comprised male (M), castrate (Cx), and testosterone-replaced castrate male (Cx + T) rats and group 2 (n = 5) consisted of male (M), female (F), and 17 beta-estradiol-replaced castrate male (Cx + E) rats. The number of plaque-forming cells (expressed as both absolute number and a percentage of all cells) was determined, and secretory status was assessed by measuring plaque areas in response to 0, 0.01, 0.1, 1, 10, and 100 nM GHRH. While mean basal GH plaque areas were similar among the treatment groups of group 1, the maximal GH plaque area was significantly decreased in Cx [16.8 +/- 2.4 vs. 26.4 +/- 3.9 X 10(6) microns2 (mean +/- SEM); P less than 0.05], but not in Cx + T (27.5 +/- 4.1 microns2) rats. The GHRH EC50 was unaffected by castration or T replacement. The percentage and absolute population of somatotrophs were reduced in Cx, but not in Cx + T, rats, while the numbers of lactotrophs remained unchanged in these treatment groups. For group 2, the mean peak GH plaque area was reduced in Cx + E (16.5 +/- 2.9 microns2; P less than 0.001) compared to that in M rats (36.2 +/- 2.3 microns2), but was not significantly different from that in F (13.0 +/- 1.5 microns2) rats. The EC50 was significantly (P less than 0.025) greater in Cx + E (10.9 +/- 2.3 nM) and F (7.9 +/- 1.6 nM) compared to M rats (2.8 +/- 0.7 nM). The absolute somatotroph and lactotroph populations were increased in Cx + E compared to M and F rats, as were the populations of other pituitary cell types. Testosterone enhances GH secretion by increasing the secretory capacity, but not the sensitivity, of somatotrophs to GHRH and by recruiting the function of a subpopulation of somatotrophs. Estradiol reduces the secretory capacity and sensitivity of somatotrophs to GHRH, but increases the population of somatotrophs, lactotrophs, and non-GH- and non-PRL-secreting cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Deletion of antigens of the Lewis a/b blood group family in human prostatic carcinoma.

The expression of antigens of the blood group Lewis a/b family were studied in a series of 42 prostatectomy specimens from patients with adenocarcinoma clinically confined to the prostate; 19 of these were later reclassified as pathologic Stage C. Staining of normal or hyperplastic versus neoplastic epithelium was assessed in routinely processed, paraffin-embedded tissue using murine monoclonal antibodies and an avidin-biotin immunoperoxidase technique. Antigens screened and the antibodies used to recognize them were Lewis a (CF4C4), Lewis b and Type 1 H (NS10), monosialosyl Lewis a I (19.9), and disialosyl Lewis a and monosialosyl Lewis a II (FH7). FH7 strongly stained the benign epithelium of all 39 Lewis positive cases, suggesting that the sialyltransferase responsible for synthesis of FH7-reactive determinants is highly active in benign prostatic tissue. When compared to the reactivity of benign epithelium in Lewis positive cases, the staining of the carcinomas was markedly reduced in 18 cases (46%) and absent in 16 cases (41%). This reduction or loss of staining of the malignant epithelium was observed for all antibodies that stained the corresponding benign epithelium of each case. In only five of the cases (13%) was the intensity of staining in the carcinoma equal to that of the surrounding benign epithelium. No cases in this latter group had recurrence of disease, whereas in the other staining groups 25-33% of the cases had recurrences; median follow-up for the entire group was 78 months. No correlation was apparent between Gleason score and the staining pattern with these antigens. In summary, antigens of the Lewis a/b family are deleted in a high percentage of cases of prostatic adenocarcinoma.

Antibodies, Monoclonal↗
PubMed1987

The efficacy of myringotomy and ventilation tube insertion in middle-ear effusions in patients with nasopharyngeal carcinoma.

Myringotomy and insertion of a grommet are effective in the management of middle-ear effusion resulting from nasopharyngeal carcinoma. The procedure was carried out in 46 ears in 30 patients, resulting in significant improvement of hearing. The complication rate of the operative procedure is not negligible in this group of patients, and it is higher if the patients had received radiotherapy at the time of operation.

Adult↗
PubMed1987

Antifertility effects of some sulphonamides and related compounds and their accumulation in the epididymides of male rats.

Nineteen sulphonamides and related drugs were screened for their antifertility effects in male rats. They were suspended in corn oil and fed orally to rats at 10 times the human dose for a period of 6 months. Of the 19 compounds tested, sulphamethazine, sulphapyridine, dapsone, sulphamethoxypyridazine, sulphaguanidine, sulphathizole, sulphamerazine and sulphadimethoxine reduced fecundity of male rats to 34.3, 37.6, 38.3, 53.6, 55.6, 58, 75 and 78.6% of control, respectively. The fall in fecundity was due to a reduction in the number of embryos compared with the number of corpora lutea per pregnant female, and, in some cases, was associated with a fall in epididymal sperm concentration and motility. Some of these compounds accumulated in the cauda epididymidis at concentrations equal to or higher than the free drug concentrations in the blood. It is proposed that the antifertility effects of some of these compounds may in part be mediated through a direct effect on epididymal stored spermatozoa, hence compromising some processes vital for fertilization.

Animals↗
PubMed1985

Enumeration of lactotropes and somatotropes among male and female pituitary cells in culture: evidence in favor of a mammosomatotrope subpopulation in the rat.

The hemolytic plaque assay technique can be used to detect specific hormone release from single pituitary cells. Using antisera raised against murine GH or rat PRL, we have enumerated the active lactotropes and somatotropes from male and female rat pituitary glands. These studies reveal sex-related differences in the number of cells exporting GH and PRL among anterior pituitary cells in culture. In the presence of human GH-releasing factor (hGRF), the mean percentage of GH cells was 53% in males and 30% in females (P less than 0.005). The mean percentage of PRL cells was 15% in males and 39% in females (P less than 0.008). These values were not significantly altered when hGRF was omitted. The sum of GH and PRL cells identified in separate plaque assays significantly exceeds the number obtained when GH and PRL cells were determined concurrently with a simultaneous plaque assay for both hormones. This difference is dependent on the presence of hGRF, since there was no difference when hGRF was omitted. These data identify the mammosomatotrope in numbers lower than previous reports. By this approach, the mammosomatotrope subpopulation numbers about 5% of all cells in culture. In summary, we demonstrate a sex-related difference in the number of cells exporting GH or PRL among pituitary cells in culture. This difference corresponds with and may underly sex-related differences in the responsiveness of GH and PRL secretion from the pituitary gland. Furthermore, a minor subpopulation of normal pituitary cells appears capable of simultaneous secretion of both GH and PRL.

Animals↗
PubMed1984

Developmental changes in the composition of, and precursor incorporation into, polypeptides of rat brain slices.

Developmental changes in both polypeptide composition and incorporation of L-[3,4(n)-3H]valine into rat brain slice polypeptides have been monitored by SDS polyacrylamide gel electrophoresis coupled with fluorography. Six polypeptide bands (mol. wt 280, 210, 117, 66, 55 and 53 k) showed developmental decreases in relative amount whilst eleven others (mol. wt 230, 156, 95, 77, 68, 62, 48, 38, 34, 28 and 18 k) showed developmental increases. The majority of these changes were accompanied by corresponding, but not parallel changes in precursor incorporation. At least one polypeptide, mol. wt 44 k, showed a developmental decrease in precursor incorporation, but little change in relative amount. Localisation of these polypeptides in SPM, myelin and mitochondrial enriched fractions has been studied.

Age Factors↗