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Biomedical subjects

F M Lai

Publications and source records attributed to F M Lai.

At least 91 records · Page 5Linked to original sources
PubMed1991

Characterization of serotonin receptors in isolated rat intramyocardial coronary artery.

The purpose of the present study was to characterize the receptor subtypes that mediate serotonin (5-HT)-induced contraction in isolated rat intramyocardial coronary artery. In coronary artery with and without endothelium, only 5-HT and alpha-methylserotonin maleate (5-HT2 agonist) elicited equipotent concentration-dependent contractions. The EC50 values for 5-HT and alpha-methylserotonin maleate in endothelium-intact arteries were 4.7 x 10(-7) and 4.5 x 10(-7) M, respectively, whereas in endothelium-denuded arteries they were 2.8 x 10(-7) and 1.9 x 10(-7) M, respectively. The other subtype agonists, such as (+/-)-8-hydroxy-dipropylaminotetralin hydrobromide (5-HT1A agonist), 1-(3-chlorophenyl)piperazine dihydrochloride and 7-trifluoromethyl-4-(4-methyl-1-piperazinyl)-pyrrolo(1,2-a)quinoxaline (5-HT1B) and 2-methyl-serotonin maleate (5-HT3), only elicited a small percentage of the maximum contraction to 5-HT. In prostaglandin F2 alpha-precontracted coronary arteries with intact endothelium or denuded of endothelium, the addition of 5-HT resulted in a further increase in tension. No relaxation was observed with 5-HT up to 1 x 10(-5) M. The contraction induced by 5-HT in artery both with and without endothelium was inhibited by ketanserin (5-HT2 antagonist) but not by l-propranolol (5-HT1 antagonist) nor by 3-tropanyl-indole-3,5-dichlorobenzoate (5-HT3 antagonist). Ketanserin, the selective 5-HT2 antagonist, effectively antagonized 5-HT-induced contraction by shifting the 5-HT response curve to the right without inhibiting the maximal response in both endothelium-intact and -denuded arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Immunohistological characteristics of the infiltrating lymphoid cells and expression of HLA class I and II antigens in nasopharyngeal carcinoma.

The immunohistological characteristics of infiltrating lymphoid cells and the expression of human leucocyte antigens class I and II (HLA-ABC and HLA-DR, respectively) were studied in 50 pre-treatment nasopharyngeal carcinomas. The majority of lymphoid cells were activated lymphocytes expressing thymocyte OKT10 marker. CD4+ cells (T-helper/inducer) out-numbered CD8+ cells (T-suppressor/cytotoxic) by at least two- to four-fold. CD22+ cells (pan-B lymphocytes) were scanty in the peri-tumoral areas and were absent in 29 out of 50 biopsies. A moderate number of cells expressing CD15 (monocytes/macrophages) were also detected. CD16+ cells (natural killer cells) were found to be sparse or absent. Expression of HLA class I and II antigens on the tumor cells in 35 biopsies was variable. HLA-ABC staining was intense in 6, reduced in 13 and partially lost in 16, whereas staining of HLA DR was intense in 7, reduced in 11 and partially lost in 17. Full expression of both antigens was demonstrable in only 2 biopsy samples. The expression of HLA antigens in the tumour had no relationship to the type or degree of lymphocytic infiltration or staging of the tumour.

Adult↗
PubMed1990

Hepatitis with isolated serum antibody to hepatitis B core antigen. A variant of non-A, non-B hepatitis?

Antibody to hepatitis B core antigen (anti-HBc) has previously been recognized to be a sensitive marker of hepatitis B virus (HBV) infection. In addition, anti-HBc has recently been suggested to be a surrogate marker for non-A, non-B hepatitis agents in donated blood. The authors studied prospectively the HBV antigen and antibody status in four patients with chronic hepatitis and persistent presence of isolated anti-HBc in their sera. The serologic and histopathologic findings of these four patients were compared with those of three groups of patients having chronic hepatitis with or without HBV markers. A low concentration of serum HBV DNA was detected in only one of the four patients with hepatitis with isolated anti-HBc and in another patient with previous HBV infection. HBV antigens and HBV DNA were not detected in the sera and liver biopsies from the remaining patients with hepatitis with isolated anti-HBc and other patients with hepatitis with or without serologic markers of previous hepatitis A or HBV infection. In contrast, all patients with chronic HBV-associated hepatitis had detectable HBV DNA, hepatitis B surface antigen (HBsAg), and hepatitis B e antigen (HBeAg) in their sera and/or liver biopsies. These findings suggest that chronic hepatitis associated with isolated anti-HBc is a heterogenous pathologic entity. The condition of some of these patients may represent a variant of non-A, non-B hepatitis, whereas the remaining patients are chronic hepatitis B carriers with low serum concentrations of HBV.

Adult↗
PubMed1990

The therapeutic dilemma of the usage of corticosteroid in patients with membranous nephropathy and persistent hepatitis B virus surface antigenaemia.

The therapeutic benefits and risks of short-term corticosteroid were investigated in 8 patients with membranous nephropathy and hepatitis B surface antigenaemia. Seven patients presented with nephrotic syndrome, and the remaining patient had significant proteinuria. Their liver function tests were normal on repeated examination. Their sera demonstrated the persistent presence of hepatitis B virus surface antigen and high titres of antibody to hepatitis B virus core antigen. Hepatitis B virus e antigens were present in the sera of 4 patients at initial presentation. Their clinical responses were compared with 7 similar patients previously treated with diuretic therapy alone and acting as historic controls. Short-term corticosteroid (6 months) with stepwise reduction resulted in an early regression of the nephrotic syndrome in 3 patients. Five patients had persistent but reduced proteinuria. Transient liver impairment was observed in 3 patients. Corticosteroid therapy induced transient viral replication with increased serum concentration of hepatitis B virus e antigen and hepatitis B virus DNA. Two of the 7 patients receiving diuretics developed spontaneous remission though apparently later than those receiving corticosteroid. Yet complications such as liver dysfunction and hypertension were not observed in the patients treated with diuretics. Our findings suggest that corticosteroid therapy could be harmful in membranous nephropathy related to hepatitis B surface antigenaemia, as activation of viral replication could occur with corticosteroid therapy.

Adolescent↗
PubMed1989

IgA nephropathy associated with chronic hepatitis B virus infection in adults: the pathogenetic role of HBsAG.

Five adult cases of IgA nephropathy associated with chronic hepatitis B virus infection were studied. Serum HBsAg and anti-HBc were present in five patients and HBeAg in four patients. Glomerular changes were typical of primary IgA nephropathy in four patients, and a mixed picture of IgA and membranous nephropathy was demonstrated in one patient. Immunofluorescence microscopy using polyclonal and monoclonal antibodies against HBsAg, HBcAg, and HBeAg revealed mesangial deposits of HBsAg in renal biopsies from four patients. One renal biopsy showed only mesangial and capillary HBcAg by polyclonal antiserum, and virus-like particles were demonstrated in the intramembranous electron-dense deposits on ultrastructural examination. Mesangial HBeAg was not detected in the renal biopsies from these patients with IgA nephropathy. As for the single patient with a mixed picture of IgA and membranous nephropathy, granular deposits of HBeAg with a distribution similar to IgG were detected in the glomerular capillary walls in addition to the mesangial deposition of HBsAg. These findings suggest that HBsAg rather than HBeAg may play a role of the pathogenesis in some of the adult patients with IgA nephropathy associated with chronic hepatitis B virus infection.

Adolescent↗
PubMed1989

Immunotactoid glomerulopathy with fingerprint immune deposits. A variant of lupus nephritis?

Immunotactoid glomerulopathy is a distinct clinico-pathological entity which has recently been defined. The term immunotactoid refers to highly organized immune depositions appearing as rod-like microtubular structures in ultrastructural examination. We describe a patient with mixed connective tissue disease who demonstrates characteristic features of immunotactoid glomerulopathy. The diagnosis was made after excluding amyloidosis, cryoglobulinaemia and lupus nephritis. In addition to immunotactoid microtubules, ultrastructural examination also demonstrated presence of fingerprint depositions which were intimately mixed with immunotactoid structures. Fingerprint deposits have been described in lupus nephritis and cryoglobulin-related nephropathy, but rarely in other glomerulonephritis. These unique findings in our patient may suggest a previously unsuspected relationship between the syndrome of immunotactoid glomerulopathy and systemic lupus erythematosus.

Adult↗
PubMed1989

Replication of hepatitis B virus with corticosteroid therapy in hepatitis B virus related membranous nephropathy.

The therapeutic effect of corticosteroid in hepatitis B virus (HBV) related membranous nephropathy was investigated in a 29-year-old chronic HBV carrier. Prednisolone (60 mg/day) was given for eight weeks and gradually reduced over the subsequent four months. In the renal biopsies taken before and after corticosteroid therapy, light microscopy revealed progression of sclerosis. Immunofluorescent staining showed glomerular capillary deposition of hepatitis B core antigen (HBcAg) by polyclonal antisera and hepatitis B e antigen (HBeAg) by monoclonal antibodies. Electron microscopy revealed 40-50 nm diameter virus-like particles in the glomeruli only from the biopsy performed after corticosteroid therapy. The serum concentrations of alanine aminotransferase, HBeAg, and HBV DNA increased with corticosteroid therapy suggesting active viral replication despite the absence of overt clinical hepatitis. Renal function did not improve and corticosteroid therapy was apparently not helpful in this patient. Our results conflict with the earlier notion that short-term corticosteroid does not interfere with a favorable outcome of the infection of the related renal disease.

Adrenal Cortex Hormones↗
PubMed1989

T-lymphocyte activation in IgA nephropathy: serum-soluble interleukin 2 receptor level, interleukin 2 production, and interleukin 2 receptor expression by cultured lymphocytes.

The present study was undertaken to examine the T-lymphocyte activation in IgA nephropathy. Serum-soluble interleukin 2 receptor (sIL2R) levels were studied in 29 IgA nephritic patients, 17 patients with chronic glomerulonephritis (non-IgA nephropathy), and 30 healthy controls during an infection-free period. No difference in serum sIL2R level was demonstrated among these three groups of subjects. However, the serum sIL2R levels of IgA nephritic patient rose significantly during clinical exacerbation with synpharyngitic macroscopic hematuria and the serum sIL2R levels fell when hematuria subsided. Mitogen-stimulated cellular interleukin 2 receptor (IL2R) expression, sIL2R release, and interleukin 2 (IL2) production were also examined in peripheral blood mononuclear cells (PBMC) cultured for 24-48 hr in 21 patients with IgA nephropathy, 17 patients with chronic glomerulonephritides, and 17 healthy controls. The total cellular IL2R expression and sIL2R release did not differ among these three groups of subjects. However, the individual T-cell subsets bearing IL2R were distinctly different between IgA nephritic patients and the other two groups of controls. IgA nephritic patients had increased activated CD4+ lymphocytes and reduced activated CD8+ lymphocytes. Furthermore, IL2 production in response to phytohemagglutinin and pokeweed mitogen stimulation was increased in lymphocytes from patients with IgA nephropathy. The IL2 production did not correlate with the quantities of cellular and sIL2R yet the cellular IL2R expression paralleled the sIL2R released by cultured lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Endothelium-dependent basilar and aortic vascular responses in normotensive and coarctation hypertensive rats.

The responsiveness of acetylcholine (ACh), nitroglycerin (NG) and norepinephrine (NE) (aorta only) in both basilar arteries (BA) and thoracic aortic (TA) rings from coarctation hypertensive rats (CHR) were studied and compared to their sham-operated normotensive control rats (SNR). The effects of these agents were also evaluated in TA or BA with and without endothelium from naive normotensive rats (NNR). Blood pressure (BP) and plasma renin activity (PRA) of CHR were significantly higher than their time-matched SNR. Endothelium removal from TA of NNR significantly enhanced NE and NG sensitivity and reduced the maximum ACh relaxation. Removal of BA endothelium of NNR abolished ACh-induced relaxation but had no effect on NG-induced relaxation. In BA from CHR at any stage of hypertension studied, the sensitivity and maximum relaxation induced by ACh or NG were not significantly different than their respective time-matched SNR. ACh sensitivity of TA did not change in 1 Day CHR but decreased in 4 and 14 Day CHR. NG sensitivity increased, did not change and decreased in 1, 4 and 14 Day CHR, respectively. NE sensitivity increased in all stages of hypertension. These data suggest that in coarctation-induced hypertension there is a complex progression of events in TA which is modulated by different mechanisms as evidenced by the changes in the effects of NE, ACh and NG at various stages of hypertension. The results also suggest that the vascular endothelium of TA but not of BA may provide an acute protective mechanism to counteract the imbalance created by the increased sensitivity of smooth muscle cells to contractile agonists in the early stage of hypertension. However, persistent hypertension appears to override this mechanism.

Animals↗
PubMed1989

Isolated presence of antibody to hepatitis B core antigen in dialysis patients: occurrence of subclinical hepatitis?

Hepatitis B core antibody (anti-HBc) has recently been recognized as a paradoxical (surrogate) marker for non-A, non-B hepatitis agents in donated blood. We studied prospectively the hepatitis B virus antigen and antibody status and liver functions in 63 uremic patients admitted consecutively to our dialysis program. Nineteen percent of uremic patients, negative for hepatitis B surface antigen (HBsAg), hepatitis B virus surface antibody (anti-HBs), hepatitis B virus DNA, and antibody to delta agents, had anti-HBc in their sera at the time of admission to maintenance dialysis. This prevalence was significantly higher than that of the medical personnel working in the dialysis unit (P = 0.043) and healthy controls (P = 0.027). The prevalence of persistent presence of isolated anti-HBc increased to 31% in these uremic patients on long-term maintenance dialysis. Four patients had developed anti-HBc alone during their course of maintenance dialysis, and the appearance of anti-HBc was preceded by blood transfusion within 4 to 8 weeks. Transient or recurrent hepatic dysfunction occurred in three of these four patients. Patients with isolated anti-HBc were characterized by a higher incidence of repeated liver dysfunction (P less than 0.005), elevated alanine transaminase levels (P less than 0.005), and a higher transfusion requirement (P less than 0.01). Our data strongly suggest that these patients with isolated anti-HBc may have acquired either hepatitis B virus infection or non-A, non-B hepatitis through repeated blood transfusions despite careful screening of the donated blood to exclude transmission of hepatitis B virus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

High prevalence of hepatitis B surface antigenaemia in nephrotic syndrome in Hong Kong.

Of 61 boys and girls with relapsing or steroid-resistant nephrotic syndrome admitted for renal biopsy, 22 had persistent hepatitis B virus surface antigenaemia despite normal liver function and an absence of previous transfusion. The prevalence of hepatitis B virus surface antigenaemia amongst nephrotic patients is significantly higher than that of the general population. Membranous nephropathy remains the commonest glomerulopathy associated with hepatitis B virus antigenaemia, and boys predominate.

Adolescent↗
PubMed1989

Comparison of polyclonal and monoclonal antibodies in determination of glomerular deposits of hepatitis B virus antigens in hepatitis B virus-associated glomerulonephritides.

The nature of hepatitis B virus (HBV) antigens in HBV-associated glomerulonephritides was investigated in 7 hepatitis B surface antigen (HBsAg) carriers with membranous nephropathy, 16 HBsAg carriers with mesangial IgA nephropathy, and 1 HBsAg carrier with a mixed picture of membranous and IgA nephropathies. Consecutive frozen sections of renal biopsy specimens were stained with polyclonal and monoclonal antibodies against HBV antigens. Glomerular capillary deposits of HBeAg and HBcAg were detected in 66% and 57% of renal biopsies from HBsAg carriers with membranous nephropathy by monoclonal and polyclonal antibodies, respectively. The discrepancy in the immunofluorescence findings resulted from the cross-reactivity of the polyclonal anti-HBcAg antiserum because it contains both anti-HBcAg and anti-HBeAg activities. Mesangial deposits of HBsAg were detected in 40% and 21% of renal biopsies from HBsAg carriers with mesangial IgA nephropathy by polyclonal and monoclonal antibodies, respectively. The authors' study confirms that HBeAg is the predominant HBV antigen deposited in HBV-associated membranous nephropathy, and glomerular HBsAg deposits are detected in some HBsAg carrier with mesangial IgA nephropathy. Careful testing and evaluation of each antibody are necessary to prevent misinterpretation.

Adolescent↗
PubMed1989

An unusual case of systemic lupus erythematosus with isolated hypoglossal nerve palsy, fulminant acute pneumonitis, and pulmonary amyloidosis.

A 53 year old Chinese man with systemic lupus erythematosus (SLE) had an isolated 12th nerve palsy and acute pneumonitis. He died of respiratory failure despite intensive treatment. A limited necropsy was performed, and amyloid deposits were identified in both lung and kidney tissue. This case is highly unusual because (a) to our knowledge an isolated hypoglossal nerve palsy associated with active SLE has never been reported; (b) only one of nine reported cases of amyloidosis in patients with SLE had amyloid deposits in the lung.

Acute Disease↗
PubMed1989

IgA nephropathy associated with ankylosing spondylitis: occurrence in women as well as in men.

Two patients (one male, one female) with ankylosing spondylitis (AS) and IgA nephropathy are described. The female patient is the first reported case to have AS and IgA nephropathy concurrently. Contrary to previously reported cases, her renal manifestation preceded her rheumatic symptoms. It is suggested that women with IgA nephropathy and AS may be overlooked as the severity of spondylitis and joint involvement is less than in men.

Adult↗
PubMed1989

Effect of ciclosporin on lymphocyte subpopulations and immunoglobulin production in IgA nephropathy.

The effect of ciclosporin on the cellular immunoregulation was examined in 19 patients with IgA nephropathy. The patients were randomly divided into two groups: 9 patients receiving oral ciclosporin (5 mg/kg/day) for 12 weeks and 10 patients receiving placebo and acting as controls. T lymphocyte subpopulations were determined using OKT monoclonal antibodies. The functional capability of lymphocytes was assessed by in vitro immunoglobulin synthesis of cultured peripheral mononuclear cells, thymidine uptake by cultured lymphocytes, and t lymphocyte activation with expression of interleukin-2 receptors. A fall of in vitro IgA production by cultured lymphocytes (p less than 0.05), a reduction of thymidine uptake by Staphylococcus aureus Cowan-stimulated cultured lymphocytes (p less than 0.05), and a reduction of activated lymphocytes expressing interleukin-2 receptor (p less than 0.05) were observed in patients after 12 weeks of ciclosporin therapy. The percentages of OKT4 and OKT8 lymphocytes and OKT4/8 ratios were not altered with therapy. A simultaneous reduction of proteinuria and a transient impairment of renal function were observed. Similar changes in cellular immune parameters and clinical response were not observed in the controls. Our study suggests ciclosporin could modulate the cellular immunity in IgA nephropathy.

Cyclosporins↗