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Biomedical subjects

K Lam

Publications and source records attributed to K Lam.

At least 91 records · Page 5Linked to original sources
PubMed1988

Interstitial radiotherapy combined with interstitial hyperthermia in the management of recurrent tumors.

During a 2-year period 31 sites in 27 patients with recurrent, previously treated tumors received a combination of interstitial 192Ir radiation (RT) with microwave hyperthermia (HT). Head and neck sites were treated most frequently (48%), with breast and vagina each representing about 20% of sites. Complete response (CR) with no local recurrence was obtained in 61%, partial response (PR) in 11 (36%), and one (3%) had less than 50% tumor regression. Of these patients, nine had no evidence of tumor following HT-RT therapy, 8/18 in the CR group and 1/11 in the PR group. Significant factors influencing CR were: radiation dose, tumor volume and duration of tumor control following the initial therapy (p less than 0.02). Treated site, histology and thermal dose were not significant factors influencing tumor regression. Complications of significance developed in one patient who had local skin necrosis. Interstitial HT-RT combination provides an effective palliative therapy for recurrent and/or persistent tumors. Randomized trials are necessary to assess the effectiveness of this combination as a component part of primary management of selected tumors.

Brachytherapy↗
PubMed1988

Antibody response to Pseudomonas aeruginosa surface protein antigens in a rat model of chronic lung infection.

For an animal model of infection to be useful in immunological studies it is necessary to establish that the surface antigens expressed by bacteria growing in vivo in the experimental infection mimic those expressed by bacteria in the human infection. In this study, chronic infection was induced by inoculating the lungs of rats with agar beads containing mucoid Pseudomonas aeruginosa. P. aeruginosa was obtained from the lungs 14 days after infection and studied without subculture. Several high-mol.-wt proteins were expressed in the outer membranes (OM) of the bacteria from the rat lungs which could be induced by cultivating the same isolate in iron-depleted conditions in vitro. The pattern of iron-regulated membrane proteins (IRMP) was similar to that obtained in an earlier study with another mucoid isolate of P. aeruginosa examined directly, without subculture, from the sputum of a cystic fibrosis patient. Immunoblotting with LPS-absorbed serum from infected rats and also with serum from CF patients showed that IgG in these fluids reacted with the IRMPs and other major OM proteins (OMPs) of P. aeruginosa. Antisera from rats immunised with whole cells of P. aeruginosa grown in iron-depleted media reacted with all the major OMPs of P. aeruginosa, including the IRMPs, confirming their immunogenicity.

Animals↗
PubMed1988

Temporal lobe and hypothalamic-pituitary dysfunctions after radiotherapy for nasopharyngeal carcinoma: a distinct clinical syndrome.

Eleven patients with combined neurological and endocrine complications after external radiotherapy for nasopharyngeal carcinoma are described. Neurologically, memory disturbance, complex partial seizures and hypodense areas in one or both temporal lobes on CT were typical features. Endocrinologically, hypopituitarism was the prominent manifestation. This constellation of clinical features in a patient with previous radiotherapy to the nasopharynx characterises radiation injury to the inferomedial aspects of the temporal lobes and the hypothalamic-pituitary axis. While the parenchymal brain lesions may mimic metastases or glioma on CT, the associated endocrine disturbance would betray the correct diagnosis. The importance of recognising the hypopituitarism which may be clinically asymptomatic and which is amenable to therapy is emphasised, as is the need for a proper fractionation of the radiation dose to minimise the incidence of these disabling complications.

Adult↗
PubMed1988

An extracorporeal model of biofilm-adherent bacterial microcolony colonization for the study of peritonitis in continuous ambulatory peritoneal dialysis.

We have developed an extracorporeal system for investigating in vitro the biofilm-adherent bacterial microcolonies (BABM) that grow on Tenckhoff catheters (TC), to study peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). A modified Robbins' device, attached to sampling plugs with TC discs and connected to the dialysate via a peristaltic pump, is run for 24 h; scrapings from pairs of TC discs are processed for assessment of viable BABM, one of each pair for culture by routine microbiology techniques and the other for examination by scanning and transmission electron microscopy (EM). No colonization was noted with fresh dialysis solutions and spent dialysates from patients without clinical peritonits; but, when bacterial suspensions were added to aliquots of the same dialysates, BABM were noted on both culture and EM. In a study of 4 patients on CAPD treatment, who had clinically evident peritonitis, routine cultures of spent dialysate were positive in only 2, but BABM were found in cultures and EM preparations of disc scrapings in all 4 cases. We conclude from these preliminary findings that this extracorporeal system is reliable, and well suited for studying the role of BABM in CAPD-associated peritonitis in vitro.

Bacterial Adhesion↗
PubMed1988

External beam and intraluminal radiotherapy in the treatment of carcinoma of the esophagus.

During a 10-year period, 46 patients with unresectable or inoperable carcinoma of the esophagus were treated with teletherapy-brachytherapy combination at the University of Southern California School of Medicine. Stage distribution was as follows: stage I, 5 (11%) patients; stage II, 23 (50%) patients; stage III, six (13%) patients; and stage IV, 12 (26%) patients. Thirteen patients were treated for recurrent disease, including 11 patients initially treated with teletherapy and two who had had surgical resection. Radiotherapy was given by teletherapy in 33 and brachytherapy in all 46 patients. An average tumor dose was 50 Gy with teletherapy and 20 Gy per application with brachytherapy. There were 25 patients who had more than one brachytherapy application. The 5-year actuarial survival rate for 28 patients with stage I or II disease was 12%, with a median of 13 months. This compared with no 5-year survivals and a median survival of 10 months for the 18 patients with stage III or IV disease. Failure at the primary site was seen in 16 (35%) patients. Complete response was seen in 20%, partial response in 76%, and no response in 4%. Treatment was well tolerated. Complications included esophageal stenosis in two patients and tracheoesophageal fistula in one. Teletherapy-brachytherapy combination is an effective treatment in the management of unresectable or inoperable carcinoma of the esophagus.

Adenocarcinoma↗
PubMed1987

Staphylococcus aureus bacteremia. Clinical, serologic, and echocardiographic findings in patients with and without endocarditis.

Seventy-two adult patients with Staphylococcus aureus bacteremia were prospectively studied clinically, serologically, and echocardiographically. Multivariate analysis identified four parameters that significantly predicted endocarditis in staphylococcemic patients at time of initial evaluation: absence of a primary site of infection; community acquisition of infection; metastatic sequelae; and valvular vegetations detected by echocardiography. Echocardiography was most predictive of endocarditis in patients with community-acquired S aureus bacteremia from an obvious primary focus. In 11 (69%) of 16 patients with endocarditis and vegetations on two-dimensional echocardiography, this technique also revealed other important findings, including ventricular dilatation, and/or underlying valvular lesions. In 18% of patients with S aureus bacteremia without stigmata of endocarditis, echocardiography provided information that led to a diagnosis of endocarditis and a subsequent change in therapy. Our findings support the routine use of two-dimensional echocardiography in all cases of community-acquired S aureus bacteremia to identify occult endocarditis in patients without classic stigmata of disease, and to provide important prognostic data in clinically apparent endocarditis.

Adult↗
PubMed1987

Combined evaluation of circulating immune complexes and antibodies to Pseudomonas aeruginosa as an immunologic profile in relation to pulmonary function in cystic fibrosis.

We developed a solid-phase radioimmunoassay with a reference standard pseudomonas antigen and used this with 125I-labeled anti-human immunoglobulin to evaluate specific antibodies to Pseudomonas aeruginosa, qualitatively and quantitatively, in sera from children with cystic fibrosis (CF) whose lungs were colonized by this bacterium. The results of this IgG assay correlated with the number of precipitin antibodies to the standard reference antigen determined by cross-immunoelectrophoresis in the same sera. Forced expiratory volume (FEV1; percentage predicted), determined as an indicator of lung injury in CF, was evaluated as an immunologic response to pseudomonas, against a profile derived from combined serial data on both the circulating immune complexes (CIC) and the Ps. aeruginosa antibodies (N = 25 CF patients; 108 sera). This revealed that in CF patients who had no specific IgG antibodies to Ps. aeruginosa and no IgG-CIC had the best pulmonary function (FEV1 = 115 +/- 14.52%) and those with high levels of antibodies to this organism and high IgG-CIC levels had the poorest lung function (FEV1 = 69.75 +/- 10.99%) (P less than 0.05). We believe that this indicates an immunologic basis for lung injury in cystic fibrosis.

Antibodies, Bacterial↗
PubMed1987

Four documented cases of eosinophilic meningoencephalitis due to Angiostrongylus cantonensis in Hong Kong.

4 cases of eosinophilic meningoencephalitis in Hong Kong are described. The major clinical features of the patients, who were 2-60 years old, were low grade fever, headache, mild meningeal signs, right facial palsy or hemiplegia. Eosinophilia in the peripheral blood and eosinophilic pleocytosis were prominent. Computerized tomography scans of brain showed a small area of attenuation with surrounding hypodense area; the lesion was resolved 1-2 months after admission to hospital. Electroencephalograms revealed abnormally slow dysrhythmia. Sections of a nematode observed in the brain of a patient who died were identified as those of young adult Angiostrongylus cantonensis. High ELISA titres against the crude antigens of this nematode were also noted in the serum of 3 patients. The disease is probably under-recognized in Hong Kong.

Adult↗
PubMed1987

Hearing-impaired children in Venezuela: 1985.

The first Venezuelan Survey of Deaf Children during the 1984-85 school year was a collaborative effort of the Ministry of Education in Venezuela and Gaullaudet University in the U.S. Limited in its first year to the capital city of Caracas, the study used a survey methodology developed over 18 years in the U.S. Annual Survey of Hearing-Impaired Children and Youth. In its first year of operation the Venezuelan study collected information on 804 deaf students, over 90% of whom were between the ages of 3 and 14, had severe or profound hearing losses (i.e., hearing level of 71 dB or greater in the better ear), and experienced their hearing impairments before the age of 3. Significant findings of the Venezuelan Survey include a large number of children (29%) with hearing losses caused by maternal rubella. This result is important to educators because rubella-deafened children tend to have other handicaps in addition to their hearing impairment. Meningitis was the most frequently reported after-birth cause of hearing losses in Caracas. Thirty-six percent of the Venezuelan students were reported to have other handicaps in addition to their hearing impairments. Survey results also raise questions about the educational status of less severely hearing impaired children and older deaf adolescents; these two groups were not reported in any significant numbers to the survey. Implications of the Venezuelan data are discussed, and, where appropriate, comparisons with data from the U.S. 1985 survey are made.

Adolescent↗
PubMed1987

Cerebral radionecrosis: is surgery necessary?

Seven patients with cerebral necrosis after radiotherapy for carcinoma of the nasopharynx are presented. The clinical features included seizures and a varying degree of intellectual impairment. In spite of significant mass effect on CT scan, the patients remained alert, ambulatory and independent. We believe that some cases of cerebral necrosis following radiotherapy for extra-cranial neoplasms present in a more benign fashion than has been portrayed in the literature, and in the absence of clinical evidence of raised intracranial pressure, surgical intervention is unnecessary. The importance of careful fractionation of an optimum radiation dose as a preventive measure is emphasised.

Adult↗
PubMed1987

Biofilms on right heart flow-directed catheters.

This study was designed to detect biofilm and bacteria on right heart flow-directed catheters using scanning electron microscopy and culture following scraping and dispersion of biofilm by sonication. We examined 20 consecutive catheters removed from 18 critically ill patients, an average of 2.6 days after insertion. On scanning electron microscopy, all catheters were found to be covered by a biofilm, with bacteria visible on 50 percent of them. Cultures of specimens from 40 percent of the catheters grew skin organisms (Staphylococcus warneri, Diphtheroid), anaerobes (Propionibacterium), and other potential pathogens (Proteus vulgaris, Enterobacter cloacae). Combination of the two techniques produced a bacterial detection rate of 75 percent. This study demonstrates that the presence of biofilm with bacterial adherence is common on right heart flow-directed catheters. The phenomenon could play a significant role in endogenous infection in critically ill patients.

Bacteria↗
PubMed1987

Prognostic implications of circulating immune complexes and Pseudomonas aeruginosa-specific antibodies in cystic fibrosis.

We re-examined the role of circulating immune complexes (CIC) in cystic fibrosis, by their serial measurement in 16 patients who had advanced lung disease and persistent specific antibodies to Pseudomonas aeruginosa in their serum. CIC were detected by 125I C1q-BA (IgG + IgM-IC) and Raji RIA (IgG-IC), and IgA-IC by a modification of the Raji RIA method. Serum precipitins to Ps. aeruginosa were detected by crossed-immunoelectrophoresis (XIE) and antibodies to alkaline protease (AP), elastase (EL) and exotoxin-A (EA) of Ps. aeruginosa were detected by ELISA technique. CIC were positive in greater than 50% of the samples in 8 patients (group A) and in less than 25% in the other 8 (group B); follow-up averaged 22 mo in group A and 26 mo in group B. The numbers of precipitins to Pseudomonas were equally high, and levels of antibodies to AP, EL, and EA of Ps. aeruginosa were similarly positive, in the 2 groups. In group A the CIC were mostly IgG-IC by Raji RIA (76%) and IgA-IC, whereas in group B C1q-binding IC (79%) and IgA-IC were more prevalent than IgG-IC by Raji RIA. Four group A children died during follow-up, together with one group B child in whom the CIC level had suddenly risen precipitously. We postulate that a high level of CIC in association with persistent specific-antibody response to Ps. aeruginosa heralds a poor prognosis in cystic fibrosis.

Adolescent↗
PubMed1987

Bacterial colonization of intestinal urinary conduit diversion: a morphologic and bacteriologic experimental study.

Cutaneous diversion of the urine through intestinal conduits results in bacteriuria with uropathogenic organisms in up to 80% of patients, many of whom suffer pyelonephritis. Analysis of the bacteriologic data from daily sampling at multiple sites and scanning and transmission electron microscopic studies of sequential loop and autopsy specimens in rabbits with functioning colonic conduits indicate that the pyelonephritis evolves in sequential stages of microbial colonization. Using these data on the natural progression of bacterial infection, we can rationally test the ability of strains of bacteria indigenous to the conduit of this animal model to prevent uropathogenic colonization of the conduit.

Animals↗
PubMed1985

A rheumatoid arthritis B cell subset expresses a phenotype similar to that in chronic lymphocytic leukemia.

An abnormal subpopulation of B cells expressing the T1 antigen, which is normally restricted to T cells, was demonstrated in the peripheral blood of 16 patients with rheumatoid arthritis. This T1+ B cell population accounted for a mean of 19.6% (upper limit 48%) of the circulating B cells and did not correlate with clinical disease activity, rheumatoid factor, or drug treatment. The highest percentage of T1+ B cells found in the blood of 8 patients with connective tissue diseases, including systemic lupus erythematosus, was 5% of the B cells, and for normal controls, it was was 3% of the B cells. As previously reported, we confirmed that the T1+,Ig+ phenotype was a feature of leukemic cells in B-type chronic lymphocytic leukemia. The finding of increased numbers of T1+ B cells in patients with rheumatoid arthritis and those with B-type chronic lymphocytic leukemia raises the possibility that these cells play a role in a spectrum of diseases, including those involving autoimmunity and malignancy.

Antibodies, Monoclonal↗