Biomedical subjects
Publications and source records attributed to R L Anderson.
A previously undescribed syndrome of bilateral blepharoptosis, ectopia lentis, and high myopia apparently was dominantly inherited and originated from a spontaneous genetic mutation. The syndrome seems to be caused by a decrease in the tensile strength of the levator aponeurosis, the zonules, and the sclera.
A rigid endoscope was used to directly examine, measure, and photograph the intranasal ostium created by an external dacryocystorhinostomy (DCR). This technique was used to examine 19 patients who underwent 22 standard external DCRs. All patients had clinically successful results, documented by a positive Jone I dye test following surgery. The dimension of the bony opening created at surgery was measured and averaged 11.84 mm in diameter. The average diameter of the healed intranasal ostium was only 1.80 mm. No statistically valid correlation between the size of the bony opening and the final size of the healed intranasal ostium could be established. Thus, a large surgical anastomosis did not necessarily result in a large healed intranasal ostium. Excellent functional results were obtained even when the intranasal ostium was quite small. Other indications for the use of this technique are discussed.
This study compares the size of the operative anastomosis with the size of the healed intranasal ostium resulting from 22 external dacryocystorhinostomies. The area of the healed intranasal ostium was approximately 2% of the area of the surgical anastomosis. No correlation was found between the size of the surgical anastomosis and the size of the healed ostium. In all cases, excellent functional results were obtained, regardless of the size of the healed ostium. This study suggests the size of the surgical anastomosis is not directly related to the success of the procedure, although it must be large enough to technically perform the procedure.
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Banded chromosome studies obtained at the time of diagnosis from 42 patients with the preleukemic syndrome had clonal abnormalities in fifteen. Using Kaplan-Meier product limit survival analysis, it was found that patients with chromosome abnormalities developed acute leukemia more frequently than those without (p less than 0.05). However, we noted that in a subset of patients with complex abnormalities and in a subset previously exposed to alkylating agents, almost all developed leukemia. When either subset was excluded from the larger group analysis there were no differences in leukemia-free survival between cytogenetically abnormal and normal groups. Thus, in the prognostic evaluation of our patients with the preleukemic syndrome a chromosome abnormality per se did not predict rapid evolution to acute leukemia. However, almost all preleukemic patients with complex chromosome abnormalities and almost all alkylator-exposed preleukemic patients can be expected to develop overt leukemia within 1 yr.
The reversibility of nitrilotriacetate (NTA)-associated nephrotoxicity was investigated by comparing renal tissues from rats fed nephrotoxic levels of NTA for 7 wk with those from rats allowed 5 wk of recovery after the 7-wk exposure. In addition the toxicity of 2% Na3NTA X H2O in the diet (73 mumol/g diet) was compared with that of 1.5% H3NTA (79 mumol/g diet). The two forms of NTA induced comparable renal tubular cell toxicity which was characterized by proximal convoluted cell vacuolation and hyperplasia. These effects were noted in all of the exposed animals although the extent of damage varied. This specific renal tubular cell toxicity was completely reversed during the 5-wk recovery period. Renal pelvic transitional cell toxicity was induced primarily by Na3NTA X H2O. Renal pelvic toxicity was characterized by hydronephrosis, and erosion, ulceration and hyperplasia of the transitional epithelium. All forms of renal toxicity except that accompanying hydronephrosis were reversed when Na3NTA X H2O feeding was discontinued.
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A case of metastatic carcinoid tumor presenting as a lacrimal fossa mass is described. This appears to be only the fourth case report of metastatic carcinoid to the orbit and the first to include ultrasound evaluation. the tumor mass did not regress despite radiation therapy as documented on serial ultrasound examinations. Therapeutic implications of this finding are discussed. Metastatic carcinoid tumors are reviewed.
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In this review a summary is presented of the experimental evidence that has led to the development of hypotheses to explain how the chronic ingestion of nitrilotriacetate (NTA), which is a non-mutagenic, non-metabolized and non-accumulating compound, might induce urinary tract toxicity that can lead to neoplasia. The hypotheses attribute the toxic process to alterations in divalent cation (M2+) distribution in the urinary tract during the processing of NTA for excretion in the urine. The hypotheses do not identify a 'carcinogen' per se but rather define conditions that must exist for the initiation and propagation of toxicity that is an essential precursor of and accompanies tumours associated with chronic, high dosage NTA ingestion. The proposed hypotheses are consistent with all available information on NTA toxicity and define ingestion doses that do not alter urinary tract M2+ distributions and do not initiate urinary tract toxicity after chronic exposure. The existence of no-effect doses that must be exceeded for the initiation and propagation of toxicity negates the validity of mathematical extrapolations of possible tumour incidence at doses below the threshold levels from the results obtained in chronic, high dosage experiments. The thresholds determined in the experimental animals are several orders of magnitude greater than human exposure via drinking-water based upon measured NTA concentrations in Canada where NTA has been used in detergents since 1970.
The mechanism by which cells develop thermotolerance is unknown but some previous results suggest that membranes are involved in the process. The lipid composition of membranes from Ehrlich ascites cells grown in tissue culture was analysed at times up to 24 hours after heat treatments at 42 to 44 degrees C known to induce thermotolerance. No changes were observed in the levels of free cholesterol and phospholipids in the cells, nor in the fatty acid composition of the phospholipids. In addition, no changes were observed in the level of cholesterol esters. When cells were fractionated into crude nuclear, mitochondrial and microsomal fractions by differential centrifugation, there was still no heat-induced change in the free cholesterol or phospholipid levels of these fractions. It is concluded that thermotolerance is not mediated through a compositional change in the membranes to a more thermostable form.