Biomedical subjects
Publications and source records attributed to G C Lee.
A series of 4-substituted 2-thiophenesulfonamides was prepared from 3-thiophenecarboxaldehyde using metalation chemistry developed for 3-furaldehyde. Several of these compounds inhibit carbonic anhydrase II in vitro at concentrations of less than 10 nM. In addition, none of these compounds exhibit sensitization potential as determined from in vitro measurement of cysteine reactivity.
A 37 year-old-woman was admitted to the hospital because of 15 days' duration of continuous fever. Routine studies for detection of fever foci were negative. Imaging studies revealed giant hemangioma of the liver with central thrombosis. The fever persisted for a period of 4 weeks, and subsided after conservative management. We report a case of hepatic hemangioma presenting with fever of unknown origin. The condition is very rare, but should be regarded as one of the causes of fever of unknown origin.
Echinostomiasis is an endemic intestinal trematodiasis of humans in Korea. We observed a human case of Echinostoma hortense infection who had ulcerations on the duodenal mucosa. A 55-year old man living in Hamyang-gun, Kyongnam, complained of epigastric pain with hematemesis in April 1994. Endoscopy revealed lesions of early gastric cancer and duodenal ulcerations. A penetrating parasite into the duodenal mucosa was picked out, and identified as E. hortense. As the patient was treated with praziquantel 10 mg/kg single dose, 3 more E. hortense and 7 Metagonimus worms were recovered. This case demonstrates that echinostomiasis causes gross ulcerations in the duodenum.
A rare case of coexisting multiple myeloma and non-Hodgkin's lymphoma at the time of diagnosis is presented. The patient presented with petechiae, melena and weight loss. IgA lambda monoclonal gammopathy in the serum and free lambda chain in urine were documented. Bone marrow biopsy demonstrated an interstitial infiltration of neoplastic plasma cells coexisting with localized collection of neoplastic lymphoid cells composed of monotonous small lymphocytes with occasional cleaved nuclei. Immunophenotype of plasma cell was IgA lambda. The patient also had a jejunal mass, with biopsy proven malignant lymphoma, diffuse small cleaved cell type. The tumor was diffusely positive for pan-B marker. After chemotherapy, the IgA lambda monoclonal protein decreased and the patient improved. This case suggest, that the seound B-cell neoplasm may have evolved by transformation of an original neoplastic clone, or that malignant tumors may be polyclonal at onset. Definitive diagnosis and staging of each disorder is important for proper management.
Antimicrobial resistance of bacterial pathogens usually varies from one geographic location to another. During the last 20 years, outbreaks of disease caused by multiresistant bacteria have occurred with higher frequency in developing countries. We investigated the antimicrobial resistance patterns of bacteria isolated in 1992 from two tertiary-care centers, in Riyadh and Texas. Of the 8841 strains used, 5318 were isolated from clinical specimens of patients at King Faisal Specialist Hospital and Research Centre, Riyadh, and 3523 were from Olin E. Teague Veterans Medical Center, Temple, Tex. Members of Enterobacteriaceae at the King Faisal hospital were significantly more resistant to frequently prescribed antimicrobials than were those at the Olin Teague center. Susceptibility to less frequently used agents like ciprofloxacin and ceftazidime was similar at both hospitals. Resistance patterns of Pseudomonas aeruginosa, Haemophilus influenzae, and coagulase-negative staphylococci were similar at both medical centers. The Olin Teague center encountered significantly more methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci.
Although most respiratory tract infections are caused by viruses, bacterial pathogens are responsible for higher morbidity and mortality. Because virtually nothing is known about the etiology of bacterial respiratory pathogens in Saudi Arabia, this study examined the incidence of these organisms in 5426 patients over a 1-year period. Of the bacterial pathogens isolated from 904 patients, the most common organism was Hemophilus influenzae (31%), followed by pneumococci (22%), Pseudomonas aeruginosa (16%), and others (31%). Because the first two organisms accounted for more than 50% of isolates, their susceptibility to commonly used antibiotics was also reviewed. The results are presented here.
A seroepidemiological study was carried out to explore the risk factors of a measles outbreak that occurred among school children at a rural village (Li-Tse) in Taiwan. Among the 1166 participants, the percentage susceptible before the outbreak was 10.5% (122/1158) which was estimated as the sum of measles IgG-negative (29/1158) and IgM-positive (93/1166) individuals. Among 340 vaccinated children, 16 (4.7%) were measles IgM-positive and 10 (2.9%) were measles IgG-negative; therefore the vaccine failure rate was estimated to be 7.6% (26/340) and vaccine efficacy was 79.7% (95% confidence interval [CI] : 65.0-88.5). The most important risk factors for acquiring measles infection were the presence of other measles cases in the family (Odds Ratio [OR] = 32.5, P = 0.002) and the presence of more than two cases in a class (OR = 29.1, P = 0.003). The physician reporting rate was 6.1% (4/66), and the sensitivity of passive measles surveillance was only 4.3% (4/93) by active serosurvey. A concomitant rubella epidemic also amplified the inaccuracy of a passive reporting system based only on clinical diagnosis. Five children developed measles IgM but did not experience any symptoms, indicating that asymptomatic measles infection can occur. Our experience has highlighted three important areas for future measles elimination: (1) the need for serological evaluation of vaccinees, particularly those who were born during the introduction of mass immunization; (2) improvement in measles vaccine efficacy; and (3) further investigations on the role of asymptomatic transmission and susceptibles who remain after mass immunization.
The behavior of nonlinear pulsatile flow of incompressible blood contained in an elastic tube is examined. The theory takes into account the nonlinear convective terms of the Navier-Stokes equations. The motion of the arterial wall is characterized by a set of linearized differential equations. The region bounded by the flexible arterial wall is mapped into a fixed area in which numerical discretization takes place. The finite element method (Galerkin weighted residual approach) is used for the solution of this nonlinear system. The results obtained are pressure distribution, velocity profile, flow rate and wall displacements along the elastic tube (20 cm long).
A total of 27,480 stool specimens from 15,548 patients with gastroenteritis were analyzed for bacterial enteropathogens during a 4-year period between 1986-89 at a major referral center in Saudi Arabia. Bacterial pathogens were isolated from 1,152 patients, Salmonella being the most frequent, followed by Campylobacter, Shigella, and Aeromonas hydrophila. The latter bacterium was found in 58 patients; seven of them were associated with other enteric pathogens, but A. hydrophila was the only organism in 51 patients. All had gastrointestinal symptoms, the most common being diarrhea (92%), followed by abdominal pain (68%), fever (37%), and vomiting (27%). Stool specimens from 1,368 control patients were negative for A. hydrophila.
A total of 3,144 clinical isolates from 3,011 consecutive patients were tested against lomefloxacin by the agar dilution method. They consisted of 1,380 isolates of Enterobacteriaceae, 527 pseudomonads, 47 Haemophilus influenzae, 53 Acinetobacter, 42 Brucella melitensis, 903 staphylococci and 192 strains of enterococci. In vitro activity of lomefloxacin was compared with ciprofloxacin, norfloxacin, beta-lactams and aminoglycosides. Over 98% of Enterobacteriaceae were susceptible to lomefloxacin with an MIC of 0.06-4.0 micrograms/ml. It also inhibited 93 and 85% clinical isolates of Pseudomonas aeruginosa and Xanthomonas maltophilia, respectively. All isolates of Haemophilus, Brucella and Staphylococcus aureus were susceptible to this fluoroquinolone. However, only 43% of the 192 strains of enterococci exhibited in vitro susceptibility. Lomefloxacin was found to be comparable to ciprofloxacin and norfloxacin in its in vitro activity, and superior to most penicillins, cephalosporins and aminoglycosides against both gram-negative and gram-positive bacteria except enterococci.
In this paper, a new theoretical model of nonlinear wave propagations in arteries with surrounding tissues was put forward. The equations of motion for the blood vessels and their peripheral tissues as a system have been derived. These equations were expressed in terms of the stresses of the vessel wall and fluid, and the geometry of the blood vessel. They can be used to solve numerically the problems for the propagations of nonlinear pulse waves in arteries together with the momentum and continuity equations of incompressible-viscous flow, as well as the constitutive equations of fluid and vessel wall. The numerical solutions can involve pressure, velocities and flowrate of the blood flow, as well as displacements, velocities and stresses of the vessel wall. These physical variables of propagations of pulse waves in arteries are all of significance physiologically and clinically.
Explore the source record for details and available documents.
Bone biopsies were performed in spinal cord injured patients with pressure ulcers in whom osteomyelitis was suspected. Roentogenograms and bone and gallium scans were also evaluated to determine their usefulness in diagnosing osteomyelitis. Infected bone underlying pressure ulcers revealed only mild focal inflammatory changes which did not correlate well with x-ray and nuclear scan abnormalities. Negative scans, however, essentially ruled out osteomyelitis. There was no clear association of delayed healing or recurrence of pressure sore with osteomyelitis. Antibiotic therapy of greater than three weeks' duration did not significantly affect the outcome of the disease.
Differential pulse voltammetry at a stationary glassy carbon electrode was used for the sensitive and selective analysis of a potent new antiviral analogue of 2-deoxyguanosine in a pharmaceutical formulation. In the electrochemical method for analysis of 9-[1,(3-dihydroxy-2-propoxy)methyl] guanine (1), an electroactive internal standard (uric acid) was used. Linear peak current-concentration relationships were obtained at 1 concentrations of 0.4-2.0 mM, with a quantitation limit of 0.1 mM. Degraded solutions of 1 were assayed directly by differential pulse voltammetry and also by two chromatographic methods to demonstrate the specificity of the electrochemical method. The voltammetric method reliably provides accurate and reproducible results in considerably less time than conventional chromatographic analysis.
Fava beans (Vicia faba) upon treatment with nitrite under simulated gastric conditions, form a direct-acting bacterial mutagen, comparable in specific activity to the most potent known mutagens for several strains of Salmonella typhimurium. The precursor of the mutagen was isolated and identified as 4-chloro-6-methoxyindole by u.v., i.r., m.s. and n.m.r. The precursor was dechlorinated with NaBH4 and PdCl2 as the catalyst and the product obtained from this reaction was identified as 6-methoxyindole. Since synthetic 4-chloro-6-methoxyindole was not available, structure activity studies were conducted on substituted indoles. Nitrosation of 4-chloroindole closely follows the results for nitrosation of 4-chloro-6-methoxyindole. The major product of nitrosation of 4-chloroindole is 4-chloro-2-hydroxy-N1-nitroso-indolin-3-one oxime. Thus, it appears that the major nitrosation product of 4-chloroindole and of 4-chloro-6-methoxyindole is a stable alpha-hydroxy N-nitroso compound. This is the first reported case of stable alpha-hydroxy N-nitroso compounds. In the presence of N-(1-naphthyl)ethylenediamine dihydrochloride (NEDD), the alpha-hydroxy N-nitroso compound rearranges to an aromatic diazonium ion which couples with the diamine to form an azo dye. Studies on nitrosation kinetics indicate that the nitrosation of indoles are relatively fast reactions. Both the structural and rate studies give strong support to the hypothesis that intragastric nitrosation of fava beans yield the putative gastric carcinogen in the high-risk area in Colombia.
Nonlinear viscoelasticity is important in a variety of studies in biomechanics. One of the subject areas is the necessity to characterize the dynamic properties of blood vessels. This study concerns a theoretical formulation to examine the higher order nonlinear viscoelastic relaxation functions for arterial tissue based on the assumption of transversely isotropic material properties. Simple numerical results for the first-order theory are compared with those available in the literature.
Based on the theory of Green and Adkins [9], a strain energy function is proposed to describe the nonlinear mechanical behavior of arteries. The arterial tissue is assumed to be a nonlinear elastic, incompressible material with local triclinicity and transverse isotropy. Although the arterial tissue shows viscous phenomena, experimental results have indicated that viscosity is only a second-order effect as compared to the nonlinear elasticity of the tissue. The advantage of the formulation presented herein is that it is relatively simple and results in an accurate stress-strain relation that can be used readily for the study of wave propagations in the blood vessels. For nonlinear finite strain elasticity of the order two, ten elastic constants are needed to describe the material nonlinearity of the arterial tissue. Based on the orthogonal, transverse isotropies and the incompressibility conditions, ten constraint equations may be established and the elastic constants can be uniquely determined by correlating with the experimental results. An example of calculating these elastic constants is made by using the experimental data of Patel, et al. [14-17] for the intercoastal arteries in living dogs. The predicted mechanical behavior of canine arteries is quite satisfactory as compared to the experimental data except when the longitudinal and the circumferential stretches exceed 1.60. However, such a strain magnitude may not be expected in in-vivo arteries because of the constraints of peripheral connecting tissues. Otherwise, the strain energy function including higher order strain terms should be used.(ABSTRACT TRUNCATED AT 250 WORDS)
A randomised blind controlled trial of hepatitis B immune globulin (HBIG) plus hepatitis B vaccine for the prevention of the perinatally transmitted HBsAg carrier state was conducted in Taipei. Infants of e-antigen-positive HBsAg carrier mothers were given HBIG immediately after birth, and then one of three schedules of vaccination. There was no difference in efficacy between the three schedules; the combined efficacy was 94%, compared with that of HBIG alone (71%) or of vaccination alone (75%). Persistent HBs antigenaemia developed in only 9 (6%) of the 159 infants receiving prophylaxis, but in 88% of the controls. Antibodies developed in all those who did not become antigenaemic and presumably will provide long-term protection from hepatitis B virus infection. HBIG should be given as soon as possible after birth and need not be given again if the infant is subsequently vaccinated. With HBIG coverage from birth, the timing of the start of vaccination does not seem to be of importance within the first month of life, but to maximise compliance and minimise costs hepatitis B vaccination should be initiated during the confinement.