Biomedical subjects
Publications and source records attributed to C Y Chan.
Two patients who developed post-operative sternotomy infections due to Nocardia asteroides were treated successfully with ofloxacin, in vitro susceptibility of the organisms being used as a guide to dosage. The place of this drug in the treatment of infection due to Nocardia asteroides merits further investigation.
Des-gamma-carboxy prothrombin (DCP) assay was performed by a staphylocoagulase method in 35 consecutive patients with small (less than 5 cm), resectable hepatocellular carcinoma (HCC). They also simultaneously received serum alpha-fetoprotein (AFP) assay. According to diagnostic strategy, patients were divided into two groups. Group I consisted of eight patients who were candidates for a mass screening project for HCC with elevated AFP levels (greater than 20 ng/ml). Five of these patients had an increased DCP level (greater than 6 U/l). Group II included 27 victims of chronic hepatitis B or cirrhosis whose tumors were detected by ultrasonography during regular follow-up. In this group, increased DCP and AFP levels were observed in 11 and 16 cases, respectively. Of 14 patients with smaller HCC (less than 3 cm), only three had elevated DCP levels, while eight patients had an abnormal AFP level. When these two assays were combined, 18 of 27 patients in group II and nine of 14 patients with smaller HCC (less than 3 cm) revealed elevation of one or both of the two markers. A total of 16 out of 35 patients with small HCC had abnormal DCP levels. In conclusion, DCP assay is less sensitive than AFP assay in the detection of small HCC, and the combination of both markers has little complementary effect.
One hundred and eight primary school students who had been vaccinated with three doses of a plasma-derived hepatitis B vaccine were randomly divided into two groups, to receive a booster dose of either the same vaccine or of a recombinant yeast-derived vaccine. The pre-booster anti-hepatitis B surface antigen (HBs) geometric mean titres (GMT) were similar in both groups (281.8 mIU ml-1 versus 295.1 mIU ml-1, p greater than 0.5). One month after booster vaccination, all the vaccinees in both groups had a marked elevation in their anti-HBs titres, the anti-HBs GMT in group 1 and group 2 being 19,952.6 and 51,286.1 mIU ml-1 (p less than 0.05), respectively. In conclusion, the recombinant yeast-derived hepatitis B vaccine was able to elicit an excellent booster response in vaccinees who had originally received a plasma-derived vaccine.
We investigated the pharmacokinetics of two intravenous (iv) dose regimens of imipenem/cilastatin in Chinese patients on chronic ambulatory peritoneal dialysis (CAPD), who had an average creatinine clearance of 3.2 ml/min/1.73 m2. Doses of 0.5 and 1.0 g produced mean peak serum imipenem concentrations of 30 and 70 mg/l respectively, about 60% of cilastatin. Peritoneal dialysis fluid (PDF) imipenem concentrations reached 20-30% of the serum peak 4-5 h after iv injection, and the lowest maximum PDF concentrations were 2 mg/l after the 0.5 g dose and 14 mg/l after 1.0 g. Thus both regimes produced PDF imipenem concentrations above the MICs of susceptible pathogens. The half-life of imipenem was 6.4 h and the plasma clearance 66 ml/min; serum and PDF imipenem were in equilibration after about 5 h. Cilastatin had a prolonged half-life of 19 h and a plasma clearance of 10 ml/min, and accumulated in both serum and PDF. With a 0.5 g dose, the pharmacokinetics of imipenem/cilastatin suggest that the combination may prove an effective treatment for peritonitis associated with CAPD.
After 3 days of treatment with ofloxacin (300 mg given orally once daily), the drug levels in serum and pleural fluid 2 and 4 h after drug administration in patients with tuberculous pleural effusion were assessed by a rapid high-performance liquid chromatography assay. The levels in serum (mean +/- standard error of the mean [SEM]) were 4.70 +/- 0.14 and 4.63 +/- 0.09 mg/liter 2 and 4 h after administration, respectively, and the levels in pleural fluid (mean +/- SEM) were 3.82 +/- 0.09 and 4.21 +/- 0.08 mg/liter, respectively. The pleural fluid-to-serum ofloxacin ratio at 2 h was 0.82 +/- 0.02 (mean +/- SEM), and the ratio at 4 h was 0.92 +/- 0.02 (mean +/- SEM). This study demonstrated very good penetration of ofloxacin into pleural fluid in tuberculous pleuritis.
Oral phosphatidylcholine at 900 mg/day was given to 4 patients with high lymph absorption for 8 weeks. Fluid and solute transfer before and after treatment were compared to 4 similar controls given placebo. None of the patients had overt ultrafiltration problems. After treatment, overnight peritoneal effluent phospholipid content did not change significantly. Ultrafiltration as well as solute and glucose transfer remained unchanged at the end of 8 weeks. A controlled trial on patients with overt ultrafiltration problems for a longer duration is required to further elucidate the role of phosphatidylcholine supplementation in patients on continuous ambulatory peritoneal dialysis.
A retrospective study of 83 cases of tuberculous pleural effusion showed that the mean age of the patients was 44 years and 10 patients (12%) were over the age of 70. Pleural fluid was smear positive for tubercle bacilli in none but culture positive in 23% of the cases. Pleural biopsy was a more sensitive method of diagnosis with granulomatous inflammation seen in 97% of cases. Five patients developed significant pleural thickening during chemotherapy requiring decortication. Twenty-two patients with tuberculous effusion diagnosed and treated over 2 years previously were traced for reassessment. None of them had significant pleural thickening and lung function tests did not show significant impairment compared to matched control subjects.
Diphenhydramine hydrochloride is an antihistamine with anticholinergic properties that is frequently used both orally and topically for the temporary relief of pruritus. Significant systemic absorption may occur following topical administration of diphenhydramine in patients with varicella-zoster lesions. We describe three children with varicella-zoster infection (VZI) who developed bizarre behavior as well as visual and auditory hallucinations following topical applications of large amounts of diphenhydramine to the majority of skin surfaces. In two cases, oral diphenhydramine was also administered. Serum diphenhydramine concentrations approximated or exceeded those previously reported. In each case, a complete resolution of mental status abnormalities occurred within 24 hours after discontinuation of all diphenhydramine-containing products. Pharmacists and other health professionals should be aware of the potential toxicity of topical diphenhydramine in patients with VZI.
Detection of TBSA was attempted in pleural aspirates of 74 patients with tuberculous and 44 patients with nontuberculous pleural effusion by gas chromatography/mass spectrometry with selected ion monitoring. The results were disappointing with a test sensitivity of 67.6 percent and a specificity of 52.3 percent. In contrast, histologic examination of pleural biopsies gave a diagnostic sensitivity of 71.0 percent. Pleural biopsy remains a better investigational procedure for the diagnosis of tuberculous pleural effusion.
11/323 patients (3.4%) with symptomatic chronic hepatitis B were positive for antibody to hepatitis C virus (anti-HCV). The positive rate of anti-HCV in patients with serum alanine aminotransferase (ALT) levels greater than 200 U/l (n = 219) did not exceed that of the patients with ALT less than or equal to 200 U/l (n = 104) (2.7% vs. 4.8%). Of the 219 patients who were positive for hepatitis B e antigen (HBeAg) and/or hepatitis B virus-DNA (HBV-DNA), 5 (2.3%) had anti-HCV, while 6/104 patients (5.8%) who were positive for antibody to HBeAg (anti-HBe) had anti-HCV (p greater than 0.1). In contrast to the anti-HCV-negative patients, the patients with anti-HCV had a higher percentage of cirrhosis in their liver histological findings (36.4% vs 5.4%, p less than 0.005). In conclusion, the prevalence of HCV superinfection in symptomatic chronic hepatitis B patients is low and HCV superinfection is not an important factor in acute exacerbation of chronic hepatitis B. However, the superinfection with HCV may exacerbate the existing liver disease and accelerate its progression.
The prevalence of antibody to hepatitis C virus among Chinese subjects in Taiwan was evaluated using a commercially available enzyme immunoassay. The overall prevalence of antibody to hepatitis C virus was 0.28% among 1,419 healthy subjects, 0.8% among 500 unselected paid blood donors and 0.4% among 793 pregnant women. The three offspring of the mothers positive for antibody to hepatitis C virus were all found to be positive for antibody to hepatitis C virus at birth but all became negative by the age of 6 mo. Among healthy subjects, none of 1,000 school children and young adolescents had antibody to hepatitis C virus. Among patients in selected "high-risk" groups, antibody to hepatitis C virus was detected in 100% of 9 hemophiliac patients who were positive for antibody to human immunodeficiency virus, in 53% of 115 intravenous drug abusers, in 34.4% of 96 hemodialysis patient and in 15.8% of 19 homosexual men who were positive for antibody to human immunodeficiency virus. Only 7.1% of 196 prostitutes, 5.9% of 34 spouses of patients positive for antibody to hepatitis C virus and 0.5% of 201 brothelgoers had antibody to hepatitis C virus. These findings suggest that hepatitis C virus is transmitted mainly by the parenteral route in Taiwan. Transmission from mother to infant is not an important mode of spread of hepatitis C virus.
Over a period of 10 months, we conducted a prospective randomized controlled trial of endoscopic injection for the arrest of peptic ulcer hemorrhage in 84 patients. We injected pure alcohol (PA, 99.8%), 50% glucose in water (G/W), 3% NaCl solution, and normal saline solution (N/S, controls) to stop bleeding. The ultimate success rates in the four groups were: 81% (17/21) in the PA group, 80% (16/20) in the 50% G/W group, 65.2% (15/23) in the 3% NaCl group, and 80% (16/20) in the N/S group (p greater than 0.05). The volume of blood transfusion (mean +/- s. e. m.) for each patient was 1,200 ml +/- 433 ml in the PA group, 1,130 +/- 356 ml in the 50% G/W group, 1,704 +/- 330 ml in the 3% NaCl group, 1,400 +/- 548 ml in the N/S group (p greater than 0.05). The duration of hospitalization (mean +/- s. e. m.) was 5.7 +/- 1.5 days in the PA group, 3 +/- 1.3 days in the 50% G/W group, 6.1 +/- 1.1 days in the 3% NaCl group, and 5 +/- 1.1 days in the N/S group (p greater than 0.05). No complication of perforation or aspiration pneumonia was observed during hospitalization. We suggest that endoscopic injection with the above solutions be used as the first line of therapeutic endoscopy for arrest of peptic ulcer hemorrhage.
Forty six patients who developed 48 episodes of peritonitis while on CAPD were randomised to receive either oral ofloxacin or intraperitoneal (i.p.) vancomycin/aztreonam. Three patients were excluded from analysis: 2 were transferred to other hospitals and 1 was later found to have candida peritonitis. Of the remainder, 22 episodes were treated with oral ofloxacin and 23 with i.p. vancomycin/aztreonam. The primary cure rate in the oral ofloxacin and i.p. vancomycin/aztreonam group was 77.3% and 87.5% respectively. There were 3 primary failures and 2 relapses in the former and 1 failure and 2 relapses in the latter group. Two of the 4 primary failures were peritonitis episodes secondary to infection with pseudomonas species. The total number of days of hospital stay was 48 and 58 respectively in the two groups. Analysis of the cost of treatment revealed that i.p. vancomycin/aztreonam was 30 times more expensive than oral ofloxacin. Despite a slightly higher cure rate with i.p. vancomycin/aztreonam, oral ofloxacin is a more cost-effective primary treatment of bacterial peritonitis in patients on CAPD especially in countries with a limited health budget.
An external electric field applied parallel to longitudinal axis of neurons selectively depolarizes either end and thereby activates voltage-sensitive conductance changes in a large population of neurons. Here, we characterized such population responses in the in vitro turtle cerebellum. The responses were recorded and analyzed using a multimodal approach: the magnetic evoked field was measured using a Superconducting Quantum Interference Device (SQUID) magnetometer, and concurrently the electric field potentials were recorded. Laminar profile and current-source density analysis were used to uncover the pattern of activation due to the applied electric field. Intracellular recording provided further information for identifying the elements producing the observed responses. Finally, pharmacological manipulations confirmed the nature of the conductance changes. Our results show that it is possible to activate a defined cell population of the cerebellum by an applied field and obtain a magnetic response of the order of 0.5-2 pT. A field applied from the dorsal to the ventral side of cerebellum produced tetrodotoxin-sensitive population spikes. This component was followed by a kynurenic acid (KYNA)-sensitive postsynaptic response, most likely comprised of Ca(2+)-mediated action potentials occurring at the proximal pole of the Purkinje cell dendrites and evoked by climbing fiber inputs. The applied electric field directed from the ventral to the dorsal side of cerebellum gave rise to a complex of responses that was made up of a KYNA-sensitive component (presumably synaptically activated) and an Mn(2+)-sensitive but KYNA-insensitive component (probably due to a directly activated calcium conductance change). This study provides insights into the effects of electric and magnetic fields applied to the nervous tissue of experimental animal and human studies.
From January 1984-December 1987, 1783 patients received combination therapy of isoniazid, rifampin, and ethambutol for the control of tuberculosis. Forty-two developed symptomatic hepatitis during the period of treatment. Fifteen were hepatitis B virus carriers, and the remaining 27 were noncarriers. The peak serum transaminase and bilirubin levels were higher in carriers. Seven carriers died of fulminant or subacute hepatic failure, and only 1 noncarrier died. Eleven carriers had detectable serum hepatitis B virus deoxyribonucleic acid during the acute stage of hepatitis. The roles of isoniazid-rifampin combination therapy and hepatitis B virus in the adverse outcomes of carriers were discussed.
A chemical marker of bacterial meningitis was sought by comparing derivatives of sterile cerebrospinal fluid (CSF) with cultures of organisms in spinal fluid and artificial media. The technique of gas chromatography-mass spectrometry with selected ion monitoring (GC-MS-SIM) was used, optimised for the analysis of fatty acids. Twenty candidate ions were screened, and an ion of mass: charge ratio (m/e) 268 was chosen for detection in clinical specimens. The origin of this marker is unknown, but it is probably the molecular ion of a C16:1 fatty acid. In 135 clinical specimens of CSF examined, the m/e 268 ion was found to be a useful marker for the common organisms that cause bacterial meningitis, giving a sensitivity of 88% and a specificity of 98%. The method was more rapid and more sensitive than conventional microscopy and culture, but CSF containing coagulase-negative staphylococci, Mycobacterium tuberculosis, Cryptococcus neoformans and some other uncommon pathogens gave inconsistent results. Many organisms produced characteristic ion profiles with multiple-ion monitoring, and this method of chemical analysis holds promise for the rapid diagnosis of bacterial infections to genus or species level.
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