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Biomedical subjects

J M Chow

Publications and source records attributed to J M Chow.

At least 19 recordsLinked to original sources
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↗
PubMed1990

Effect of rumen-protected methionine and lysine on casein in milk when diets high in fat or concentrate are fed.

To examine the effect of supplying methionine and lysine on milk N composition, isoenergetic, isonitrogenous diets containing 50:50 with 3.9% added fat or 25:75 forage to concentrate with no added fat were fed with or without rumen-protected methionine and lysine to four primiparous and four multiparous early lactation (36 d in milk) Holstein cows in two 4 x 4 Latin squares. Diets contained 1.7 Mcal NE1 and were fed for ad libitum intake. Periods were 21 d. Rumen-protected methionine and lysine increased total N and casein N percentage with the 3.9% fat, but did not increase total N and casein N percentage with the diet without fat. Whey N percentage was greater with the no fat than with the 3.9% fat diet. Whey N percentage was not affected by adding amino acids. Nonprotein N percentage was greater for the diet with the 3.9% fat than with no fat. Proportions of casein N or whey N to total N were unaffected by treatments. Adding methionine and lysine to diets did not increase yields of total N and casein N. The 3.9% fat diet increased proportions of long-chain (C18:0 and C18:1) and decreased proportions of short- to medium-chain fatty acids (C8 to C16) in milk fat. Plasma nonesterified fatty acids and triglyceride concentrations were greater with the 3.9% fat as compared to the no fat diet. Methionine and lysine decreased plasma triglyceride concentrations with the 3.9% fat diet. Milk yields, DM intakes, and plasma glucose concentrations were unaffected by treatment.

Animal Feed↗
PubMed1989

Radiotherapy or surgery for subclinical cervical node metastases.

This retrospective study compared elective neck dissection with elective neck radiotherapy for the control of subclinical nodal metastases. Four hundred ninety-eight patients with head and neck primary cancers and no clinically apparent neck metastases on initial presentation comprised the study population. Each patient was followed up for at least 5 years to detect failure to control neck metastases and control of the primary tumor at the time of neck recurrence. Analysis of neck recurrences occurring in patients with control of the primary tumor showed that there was no statistically significant difference between elective radiation therapy to the neck and elective neck dissection for oral cavity, oropharyngeal, and laryngeal cancers. The only statistically significant difference was noted for hypopharyngeal cancers, with radiation therapy being more effective than surgery.

Carcinoma, Squamous Cell↗
PubMed1989

Invasive sinonasal polyps causing ophthalmoplegia, exophthalmos, and visual field loss.

In a 20-year-old man with a history of sinonasal polyps, bilateral ophthalmoplegia, exophthalmos, and optic nerve dysfunction developed. Radiologic imaging showed a polypoid mass filling the nose and sinuses, eroding into the pituitary fossa, basal cisterns, and orbits, and compressing the cavernous sinuses. Six months after bilateral maxillary, ethmoid, and sphenoid exploration, ocular motility returned to normal, but there remained mild generalized visual field loss in the right eye. The pathologic specimen showed polypoid respiratory mucosa with acute and chronic inflammation as well as eosinophiles.

Adult↗
PubMed1989

Evaluation of CSF rhinorrhea by computerized tomography with metrizamide.

This study evaluates the ability of metrizamide computerized tomographic cisternography (MCTC) to delineate the site of leakage in patients with cerebrospinal fluid (CSF) rhinorrhea. From 1981 to 1986, thirteen patients were examined by MCTC to localize the site of CSF leakage. A total of 17 studies were performed. Thirteen scans (76%) identified the site of CSF leakage. Nine of these scans were confirmed surgically. The other four scans were performed on patients who refused surgery. Of the 15 scans in patients with active CSF leaks, 13 (87%) were positive. Of the two patients with inactive CSF leaks, neither was positive. One patient is presented in whom MCTC was both diagnostic and therapeutic. In conclusion, MCTC has a high success rate in localizing the site of active CSF leaks.

Adult↗
PubMed1989

Potential use of in vivo proton spectroscopy for head and neck lesions.

Early experience with in vivo MRS has shown its potential for obtaining biochemical information, thus enhancing the diagnostic sensitivity of MRI studies. Further work on combined MRI and in vivo MRS is needed, with the goal of characterization and abnormal conditions according to their spectral patterns and for identification of tumor markers. We presented in this communication our preliminary results. It seems that the resonance from melanin can be used as a marker for melanotic tumors.

Biomarkers, Tumor↗
PubMed1989

Congenital neck masses.

Neck masses are frequently encountered in children. Although they are most often due to past infections, they may be of congenital origin. A neck mass in an adult may also be benign and of congenital origin. Common congenital neck masses include thyroglossal duct cysts, branchial anomalies, cystic hygromas and hemangiomas. Cysts, sinuses and fistulas may arise from the branchial apparatus.

Branchioma↗
PubMed1989

Radiologic assessment preoperative to endoscopic sinus surgery.

At our institution, the screening coronal section CT scan has largely replaced the use of the sinus series for the initial evaluation of patients suspected to have sinus pathology. However, in those patients with obvious mucosal disease on endoscopic examination, the screening coronal section CT scan is bypassed and a complete coronal section CT scan obtained. Axial section CT scans are not routinely obtained and bone windows are consistently selected for viewing.

Endoscopy↗
PubMed1988

Kinetics and subsite mapping of a D-xylobiose- and D-xylose-producing Aspergillus niger endo-(1----4)-beta-D-xylanase.

A previously described endo-(1----4)-beta-D-xylanase produced by Aspergillus niger was allowed to react with linear unlabeled and labeled D-xylo-oligosaccharides ranging from D-xylotriose to D-xylo-octaose. No evidence of multiple attack or of condensation and trans-D-xylosylation reactions was found. Maximum rates and Michaelis constants were measured at 40 degrees and pH 4.85. The former increased with increasing chain-length from D-xylotriose through D-xylohexaose to approximately 70% of that on soluble larchwood D-xylan, and then decreased slightly for D-xyloheptaose and D-xylo-octaose. Michaelis constants decreased monotonically with increasing chain-length. Bond-cleavage frequencies were highest near the reducing end of short substrates, with the locus of highest frequencies moving towards the middle of larger substrates. These data indicated that the endo-D-xylanase has five main subsites, with the catalytic site located between the third and fourth subsites, counting from the nonreducing end of the bound substrate. The subsite to the nonreducing side of the catalytic site strongly repels its corresponding D-xylosyl residue, while the two subsites farther towards the nonreducing end of the substrate strongly attract their corresponding residues. The subsite to the reducing side of the catalytic site moderately attracts D-xylosyl residues, while the next one towards the reducing end has a high affinity for them. The residual error of the numerical estimation was allocated largely to the Michaelis constants of the different D-xylo-oligosaccharides, whose calculated values were appreciably smaller than measured values, especially for shorter substrates. This suggests that the subsite model cannot fully account for the experimental data. Estimated and measured values of maximum rates, bond-cleavage frequencies, and dissociation constant when the active site is fully occupied by substrate agreed more closely with each other.

Aspergillus niger↗
PubMed1988

Sudden sensorineural hearing loss.

Sudden sensorineural hearing loss has many causes and treatments. The family physician can identify the hearing loss, perform audiometry, identify likely systemic causes and counsel the patient on the prognosis. Most patients are ultimately found to have idiopathic sensorineural hearing loss, and the spontaneous recovery rate is high. If no improvement occurs within one month, evaluation to rule out tumor is recommended.

Adolescent↗
PubMed1988

Head and neck: high field magnetic resonance imaging versus computed tomography.

A comparative review of head and neck lesions examined with both CT and MRI showed that the location and extent of lesions can be more precisely evaluated with MRI. MRI allows better differentiation of neurogenic tumors from other lesions. Vascular structures are easily visualized on MRI without intravenous contrast and can easily be differentiated from lymph nodes. However, cystic lesions and necrotic nodes sometimes could not be differentiated from solid lesions when using MRI.

Branchioma↗
PubMed1986

Primary mandibular reconstruction using the AO reconstruction plate.

Primary reconstruction of segmental defects of the mandible following cancer resection remains a major problem. In 1976, a stainless steel plate was developed by AO/ASIF (Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation) for mandibular reconstruction. This plate completely stabilizes both mandibular stumps without the need for intermaxillary or external fixation. In addition, when bone grafting is performed, the design of this plate promotes revascularization by allowing maximal contact between grafted cancellous bone and surrounding soft tissue. Since April 1985, we have used this reconstruction plate in six patients undergoing composite resection. The technique did not compromise cancer resection, excessively prolong operating time, or alter postoperative management. All six patients have retained the AO reconstruction plate and have been reconstructed successfully with achievement of satisfactory function and cosmesis.

Adult↗