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Biomedical subjects

J M Chow

Publications and source records attributed to J M Chow.

At least 37 records · Page 2Linked to original sources
PubMed1994

Cytogenetic studies, ras mutation, and clinical characteristics in primary myelodysplastic syndrome. A study on 68 Chinese patients in Taiwan.

Cytogenetics and clinical features were studied for 68 Chinese patients with primary myelodysplastic syndrome (MDS). Ras mutation was analyzed in 25 of them. Thirty-four patients (50%) had clonal chromosomal abnormalities at initial analysis. The most common cytogenetic aberrations were -7, +8, 5q-, and 20q-, which occurred in 11 (16.2%), seven (10.3%), five (7.4%) and three patients, respectively. The incidence of -7 was higher and that of 5q- lower in our patients than in patients from most other geographic areas. The 17 patients with multiple chromosomal abnormalities had a significantly shorter median survival (9 months) than the 34 patients with normal karyotype (33 months) and the 17 patients with patients with single anomalies (26 months). Evolution to acute leukemia occurred in 20 patients (29%) after a median interval of 8 months following the diagnosis. Patients with multiple cytogenetic changes at initial analysis or in subsequent studies had a significantly higher frequency of acute transformation than others (55% vs. 18.6%, p = 0.007); the same was not true if only the data of initial study were considered. Serial cytogenetic studies are important in patient follow-up. N-ras mutation was detected in 5 (20%) of 25 patients within the study. There was no correlation between the gene mutation and acute transformation. But combing the data of N-ras mutation and cytogenetics, patients with either the N-ras mutation or clonal chromosomal abnormalities were at significantly higher risk for developing acute leukemia than those with neither of the changes (77% vs. 25%).

Adolescent↗
PubMed1994

A case of intractable sneezing: 'a pleasure sent from God?'.

Sneezing or sternutation is usually the physiologic response to nasal irritation. The reflex follows a very complicated pathway requiring coordinated communication between the trigeminal and nervous terminalis afferent impulses as well as from glottic and inspiratory muscles in the efferent limb. When the reflex pathway is unbalanced, sneezing can increase in frequency and severity to the extent that some patients become disabled. We present the clinical examination, differential diagnosis, and treatment modalities for the case of an adolescent male who experienced debilitating intractable sneezing for more than one year. As for many of the patients described with this elusive diagnosis, our patient appears to have a functional etiology.

Adolescent↗
PubMed1994

Vasoconstrictive effects of cocaine and lidocaine with epinephrine in the hamster cheek pouch model.

Otolaryngologists frequently use cocaine and lidocaine with epinephrine for their anesthetic and vasoconstrictive effects. However, no studies have visually compared the vasoconstrictive effects of cocaine to lidocaine with epinephrine. This study used the everted hamster cheek pouch model to assess the vasoconstrictive effects of cocaine and lidocaine with epinephrine by measuring the diameter changes of arterioles. Our results showed that locally injected 1% lidocaine with 1:100,000 units epinephrine caused the greatest diameter reduction in arterioles to 32% of the initial resting diameter. Topical 1% lidocaine with 1:100,000 units epinephrine caused a gradual reduction in diameter with findings equivalent to those of injected 1% lidocaine with 1:100,000 units epinephrine at 30 minutes. Topical 5% cocaine HCl showed a minimal response, with a reduction to only 85% of the resting arteriolar diameter. Topical NaCl and injected NaCl controls showed no significant arteriolar reduction. Vasoconstrictive differences between the preparations were statistically significant (p < 0.05). Five percent cocaine is a much weaker vasoconstrictor than locally injected 1% lidocaine with 1:100,000 units epinephrine.

Administration, Cutaneous↗
PubMed1994

Rhinologic headaches.

From January 1, 1991, to June 30, 1992, 18 patients were identified as having rhinologic sources for their primary symptom of facial pain or headache. These 18 patients satisfied certain inclusion and exclusion criteria to identify the site of origin of the headaches or facial pains as coming from the nasal cavities or paranasal sinuses. The majority of these patients (12 patients) were determined to have a septal spur causing the facial pain or headache. Other identified causes included retention cysts (3 patients), mucosal contact points (2 patients), and a dehiscent infraorbital nerve (1 patient). Fifteen of these 18 patients (83%) were significantly improved or cured of their facial pain or headache after medical or surgical therapy. The 3 patients who had either a minimal improvement or no improvement in their facial pains or headaches included 1 patient with an area of mucosal contact between the middle turbinate and the bulla ethmoidalis and 2 patients with septal spurs. In summary, medical or surgical therapy can be beneficial in the treatment of patients with headaches or facial pains of rhinologic origin.

Adult↗
PubMed1994

Binding of radiolabeled monensin and lasalocid to ruminal microorganisms and feed.

Gram-negative, ionophore-resistant ruminal bacteria and Gram-positive, ionophore-sensitive species bound similar amounts of [14C]lasalocid, but neither group bound large amounts of [14C]monensin. Membrane vesicles also bound more lasalocid than monensin (P < .05). The binding was first-order at low cell or vesicle concentrations and saturable at high cell or vesicle densities. Streptococcus bovis was inhibited by both monensin and lasalocid (5 microM), but cells that were re-incubated in medium lacking ionophore grew rapidly. Lasalocid-treated cells grew very slowly when they were resuspended in fresh medium. Based on these results, it seemed that lasalocid had a higher affinity for bacterial membranes than monensin. Mixed bacteria, however, bound nearly equal amounts of [14C]monensin and [14C]lasalocid (P > .05). Monensin binding was greatly reduced when the mixed ruminal bacteria were pretreated with Tris+EDTA (P < .05), but Tris+EDTA did not affect the binding of lasalocid. Mixed ruminal protozoa always took up more lasalocid than monensin (P < .05), but feed particles bound equal amounts of [14C]lasalocid and [14C]monensin (P > .05). Based on the binding capacity of mixed ruminal bacteria, ruminal protozoa, and feed particles, there would be little free ionophore in ruminal fluid.

Animal Feed↗
PubMed1993

Phylogeny of the ammonia-producing ruminal bacteria Peptostreptococcus anaerobius, Clostridium sticklandii, and Clostridium aminophilum sp. nov.

In previous studies, gram-positive bacteria which grew rapidly with peptides or an amino acid as the sole energy source were isolated from bovine rumina. Three isolates, strains C, FT (T = type strain), and SR, were considered to be ecologically important since they produced up to 20-fold more ammonia than other ammonia-producing ruminal bacteria. On the basis of phenotypic criteria, the taxonomic position of these new isolates was uncertain. In this study, the 16S rRNA sequences of these isolates and related bacteria were determined to establish the phylogenetic positions of the organisms. The sequences of strains C, FT, and SR and reference strains of Peptostreptococcus anaerobius, Clostridium sticklandii, Clostridium coccoides, Clostridium aminovalericum, Acetomaculum ruminis, Clostridium leptum, Clostridium lituseburense, Clostridium acidiurici, and Clostridium barkeri were determined by using a modified Sanger dideoxy chain termination method. Strain C, a large coccus purported to belong to the genus Peptostreptococcus, was closely related to P. anaerobius, with a level of sequence similarity of 99.6%. Strain SR, a heat-resistant, short, rod-shaped organism, was closely related to C. sticklandii, with a level of sequence similarity of 99.9%. However, strain FT, a heat-resistant, pleomorphic, rod-shaped organism, was only distantly related to some clostridial species and P. anaerobius. On the basis of the sequence data, it was clear that strain FT warranted designation as a separate species. The closest known relative of strain FT was C. coccoides (level of similarity, only 90.6%). Additional strains that are phenotypically similar to strain FT were isolated in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1993

Once-a-day therapy for sinusitis: a comparison study of cefixime and amoxicillin.

The efficacy and safety of a once-a-day antibiotic in the treatment of sinusitis was studied. Two randomly assigned groups were treated with either once-a-day cefixime, a third generation cephalosporin, or amoxicillin three times a day. One hundred and fourteen patients were evaluated with antral punctures, microbiologic evaluation, and radiographic studies. Cultures revealed 40% gram-negative organisms, 48% gram-positive, and 12% anaerobes. The most common bacteria were Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus and viridans group streptococci. Ninety-four percent of the cefixime group were cured compared with 96% of the amoxicillin group. Staphylococcus resistance was a problem in both groups, necessitating an occasional change to amoxicillin-clavulanate potassium in the amoxicillin group. Once-a-day antibiotics offer the potential for improved compliance in the treatment of sinusitis. Cefixime offers an additional benefit of covering beta-lactamase producing strains of bacteria which are increasing in incidence and resistant to many penicillins.

Administration, Oral↗
PubMed1993

Another theory for the action of ruminal buffer salts: decreased starch fermentation and propionate production.

Sodium carbonates have been fed to ruminants for more than 20 yr and, in many cases, have alleviated milk fat depression. These effects usually have been ascribed to increased ruminal buffering capacity, but this mode of action has several problems. For the buffering capacity to increase, the concentrations of ruminal bicarbonate, dissolved CO2, and Na have to increase. Ruminal fluid already is saturated with CO2, and the cation concentration of ruminal fluid is regulated closely to prevent hemoconcentration or hemodilution. Based on these latter observations, a significant increase in ruminal buffering capacity is unlikely. The action of bicarbonates is explained more easily by increased water intake, increased ruminal fluid dilution rate, increased flow of undegraded starch from the rumen, and decreased ruminal propionate production.

Animals↗
PubMed1993

Epithelial tumors of the paranasal sinuses and nasal cavity.

This article addresses the various epithelial tumors of the nasal cavity and paranasal sinuses. It emphasizes the radiologic evaluation of patients with these tumors and the radiologic findings of importance. The advantages and disadvantages of the use of computed tomographic (CT) and magnetic resonance (MR) imaging in this evaluation are stressed.

Carcinoma↗
PubMed1992

Effect of pH and Monensin on Glucose Transport by Fibrobacter succinogenes, a Cellulolytic Ruminal Bacterium.

Fibrobacter succinogenes S85, a cellulolytic ruminal bacterium, required sodium for growth and glucose uptake. Cells which were deenergized with iodoacetate (500 muM) could not take up [C]glucose. However, deenergized cells which were treated with valinomycin, loaded with potassium, and diluted into sodium or sodium plus potassium to create an artificial electrical gradient (DeltaPsi) plus a chemical gradient of sodium (DeltapNa) or DeltapNa alone transported glucose at a rapid rate. Cells which were loaded with potassium plus sodium and diluted into sodium (DeltaPsi with sodium, but no DeltapNa) also took up glucose at a rapid rate. Potassium-loaded cells that were diluted into buffers which did not contain sodium (DeltaPsi without sodium) could not take up glucose. An artificial ZDeltapH which was created by acetate diffusion could not drive glucose transport even if sodium was present. The maximum rate and affinity of glucose transport (pH 6.7) were 62.5 nmol/mg of protein per min and 0.51 mM, respectively. S85 was unable to grow at a pH of less than 5.5, and there was little glucose transport at this pH. When the extracellular pH was decreased, the glucose carrier was inhibited, intracellular pH declined, the cells were no longer able to metabolize glucose, and DeltaPsi declined. Monensin (1 muM) or lasalocid (5 muM) decreased intracellular ATP and dissipated both the DeltaPsi and DeltapNa. Since there was no driving force for transport, glucose transport was inhibited. These results indicated that F. succinogenes used a pH-sensitive sodium symport mechanism to take up glucose and that either a DeltaPsi or a DeltapNa was required for glucose transport.

Journal Article↗
PubMed1992

Successful treatment of cytomegalovirus pneumonitis with ganciclovir and high-dose intravenous immunoglobulin in a bone marrow transplant recipient.

A 35-year-old man with acute lymphoblastic leukemia in second remission received an allogeneic bone marrow transplant from an HLA-compatible sibling donor. Unfortunately, cytomegalovirus (CMV) pneumonitis was histologically documented on Day +72. Combination therapy with ganciclovir (9-[2-hydroxy-1-(hydroxy-methyl) ethoxymethyl] guanine) and high-dose intravenous immunoglobulin (IVIG) was started immediately. The treatment comprised a three-week induction course (ganciclovir, 2.5 mg/kg q8h and IVIG, 500 mg/kg qod) and a seven-week fixed-dose maintenance course (ganciclovir 5 mg/kg thrice a week for 20 doses and IVIG 500 mg/kg twice a week for eight doses). The pneumonia resolved gradually, and he was free from symptoms within two weeks. The only significant side effect was moderately severe myelosuppression which was reversible after discontinuation of ganciclovir. The patient had a relapse of leukemia on Day +186, but there was no recurrence of CMV pneumonitis. This result confirms that such combination therapy is effective in the treatment of CMV pneumonitis in a patient with a bone marrow transplant.

Adult↗
PubMed1991

13-cis-retinoic acid induces cellular differentiation and durable remission in refractory cutaneous Ki-1 lymphoma.

A 35-year-old man with refractory cutaneous Ki-1 lymphoma was salvaged successfully with oral 13-cis-retinoic acid (1 mg/kg/day). He had a complete remission lasting for 20 months before a single nodule recurred on his skin. Excisional biopsy of the recurrent tumor revealed a distinct morphologic change, suggesting cellular differentiation toward a more benign phenotype. No significant side effects were noted except mild xerostomia, bone pain, and hyperlipidemia. The authors believe that 13-cis-retinoic acid should be considered in the treatment of cutaneous Ki-1 lymphoma.

Adult↗
PubMed1990

The association between Chlamydia trachomatis and ectopic pregnancy. A matched-pair, case-control study.

We performed a case-control study of the association of past exposure to Chlamydia trachomatis and ectopic pregnancy with 306 case patients with an ectopic pregnancy and 266 pregnant patients who served as controls. The geometric mean antichlamydial antibody titer among cases was 75 +/- 10.2 vs 13 +/- 11.0 among controls. The matched-pair odds ratio for ectopic pregnancy and IgG titer of 1:64 or greater to C trachomatis was 3.0 (95% confidence interval, 2.1 to 4.4). Adjusting for age at first intercourse, total lifetime partners, douching, history of infertility, and parity yielded a relative risk of 2.4 (95% confidence interval, 1.5 to 3.3). Current douching remained an independent risk factor after controlling for chlamydial exposure, with an adjusted relative risk of 2.1 (95% confidence interval, 1.3 to 3.5). The population attributable fraction for chlamydial infection was 0.47 and that for douching was 0.45. The results stress the need for control of C trachomatis infections and for further study of specific douching behaviors as risk factors for ectopic pregnancy.

Adult↗
PubMed1990

Vascular changes in the nasal submucosa of chronic cocaine addicts.

A detailed, correlative, histologic evaluation of postmortem changes in the nasal mucosa of chronic cocaine users has shown characteristic mucosal and arteriolar changes as well as typical perivascular and subepithelial alterations compatible with chronic inflammation. These findings confirm and extend recent reports on the effects of cocaine in the coronary circulation and heart muscle as well as provide a new diagnostic tool to the forensic pathologist who suspects that a decedent has been a long-term cocaine abuser.

Adult↗
PubMed1990

Effect of ionophores and pH on growth of Streptococcus bovis in batch and continuous culture.

Batch cultures (pH 6.7) of Streptococcus bovis JB1 were severely inhibited by 1.25 and 5 microM lasalocid and monensin, respectively, even though large amounts of glucose remained in the medium. However, continuous cultures tolerated as much as 10 and 20 microM, respectively, and used virtually all of the glucose. Although continuous cultures grew with high concentrations of ionophore, the yield of bacterial protein decreased approximately 10-fold. When pH was decreased from 6.7 to 5.7, the potency of both ionophores increased, but lasalocid always caused a larger decrease in yield. The increased activity of lasalocid at pH 5.7 could largely be explained by an increased binding of the ionophore to the cell membrane. Because monensin did not show an increased binding at low pH, some other factor (e.g., ion turnover) must have been influencing its activity. There was a linear increase in lasalocid binding as the concentration increased, but monensin binding increased markedly at high concentrations. Based on the observations that (i) S. bovis cells bound significant amounts of ionophore (the ratio of ionophore to cell material was more important than the absolute concentration), (ii) batch cultures responded differently from continuous cultures, and (iii) pH can have a marked effect on ionophore activity, it appears that the term "minimum inhibitory concentration" may not provide an accurate assessment of microbial growth inhibition in vivo.

Culture Media↗