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Biomedical subjects

J H Nelson

Publications and source records attributed to J H Nelson.

At least 19 recordsLinked to original sources
PubMed1992

Breakthrough time and adsorption capacity of respirator cartridges.

A model developed in previous studies was applied to investigate the respirator cartridge contaminant breakthrough of 121 different chemical compounds. Included in this set of 121 contaminants are representative examples of various types of organic compounds, (e.g., acetates, ketones, aromatics, alcohols, amines, alkanes, chlorinated hydrocarbons). Intrinsic to the model are two important parameters, k' (a rate constant) and tau (50% breakthrough time). Values of the two parameters pertinent to an assault concentration of 1000 ppm were determined for each of the 121 organic compounds. These values were used to calculate the breakthrough time at specified fractional breakthrough as well as the respirator cartridge loading capacity under various conditions. An approach was presented that permits the determination of contaminant loading capacity (on carbon) as a function of breakthrough time at a specified assault concentration. The effect of contaminant assault concentration on the saturation capacity was investigated for various combinations of nine different compounds and three different types of respirator cartridges. Calculated saturation capacity data derived from application of the model compare favorably (+/- 5%) with corresponding experimental data. Saturation capacities calculated by using the model addressed in this study were compared with corresponding results previously calculated by others using the Dubinin adsorption isotherm.

Acetates↗
PubMed1992

A theoretical model for respirator cartridge service life for binary systems: application to acetone/styrene mixtures.

A theoretical model, developed previously to assess respirator cartridge service life, was applied to various acetone/styrene binary assault systems. Experimental data, collected for several binary mixtures differing only with respect to the concentration of each of the two compounds, were interpreted in terms of the model. Styrene concentrations varied from 228 to 1578 ppm; the range of acetone concentrations was 92-985 ppm. The specific influence of the compound assault concentrations on respirator cartridge service life was carefully characterized, as break-through curves were generated for both acetone and styrene for each of several different binary systems. Specifically, experimental data for each system were used to determine values of the following theoretical parameters: k'1, tau 1, k'2, tau 2, and Am. These parameters were employed with the theory to generate complete theoretical breakthrough curves and to determine the time-dependence of the weight of each compound adsorbed by the respirator cartridge carbon bed. An interesting phenomenon observed for the acetone/styrene systems was the displacement (from the carbon) of previously adsorbed acetone molecules by styrene molecules. Acetone breakthrough was observed first in each of the systems studied. Following the onset of this breakthrough, the acetone breakthrough concentration was enhanced by the displacement of acetone from the carbon bed by the adsorption of styrene. The theoretical model accurately predicts both this enhancement and the associated breakthrough characteristics of styrene. In addition, the theory is capable of predicting the ratio of the number of displaced acetone molecules to the corresponding number of displacing styrene molecules. For these studies, this ratio ranged from 0.3 to 0.7. The service life of respirator cartridges exposed to acetone/styrene mixtures depends on the assault concentration of each compound and is significantly influenced (shortened) by the displacement phenomenon.

Acetone↗
PubMed1978

An inexpensive computer-aided system for quantitative echocardiography.

A comprehensive system has been developed to quantitatively analyze standard M-mode pediatric echocardiograms. It utilizes relatively inexpensive hardware together with a telephone coupling to a time-sharing computer. A complete patient report on the study is printed out upon completion, and all the data are digitally stored for future research computations. Initial and operating costs for this system are significantly less than for any comparable one available.

Diagnosis, Computer-Assisted↗
PubMed1978

Oral calcium tolerance and urinary cyclic AMP in urolithiasis.

Oral calcium tolerance and urinary cyclic AMP testing was used in the evaluation of 61 unselected patients with stones. The oral calcium tolerance test was easy to perform and was useful in defining several distinct metabolic abnormalities contributing to calculous formation. Oral calcium tolerance testing is more precise than twenty-four-hour urinary calcium determination and should provide a means of determining proper medical treatment of urolithiasis. Urinary cyclic AMP was disappointing as a measure of parathormone activity.

Adolescent↗
PubMed1978

Child health assessment and screening using a volunteer staff.

A child health assessment and screening program, staffed by volunteers, has evaluated approximately 5,000 children in a general pediatric clinic. A sample of 500 children was studied to determine characteristics of the population served, quality of the work of the volunteers and the number of new problems identified. Use of well-trained volunteers, provided with adequate supervision and follow-up physical examination of the children, identified many new problems at minimal cost and proved an effective means of expanding quality health care.

Adult↗
PubMed1977

Observations on the surface area of the abnormal transformation zone associated with intraepithelial and early invasive squamous cell lesions of the cervix.

The apparent area of the abnormal transformation zone (TZ) of the cervix was measured in a total of 104 patients by a simple method with the use of the 1 and 5 mm. diameter circle in the center of the field of the Leisegang colposcope and the field of the colposcope itself. The visible area (mean +/- S.E.M.) of the abnormal TZ for five patients with microinvasive or occult carcinoma of the cervix (180.8 mm.2 +/- 62.2) was significantly larger (p less than 0.01) than that of 64 patients with major intraepithelial lesions (62.5 sq. mm.2 +/- 7.3) and 35 patients with minor intraepithelial lesions (45.8 sq. mm.2 +/- 11.7). The visible area of the abnormal TZ measured over 40 mm.2 in each of the five patients with invasive lesions but in only 42 of 99 (42%) patients with intraepithelial lesions. The TZ extended into the endocervical canal and could not be fully visualized in four (80%) of the patients with invasive lesions, 24 (38%) of patients with major intraepithelial lesions, and 11 (31%) of patients with minor intraepithelial lesions. The implications of these findings are discussed.

Adolescent↗
PubMed1977

Oral contraceptives and cervical carcinoma.

In a case-control study, 689 consecutive patients with cervical carcinoma were studied for their use of oral contraceptives. The control patients were matched for age, ethnic origin, age at first pregnancy, age at first coitus, and socioeconomic status. There was no significant difference between case and control subjects in the duration or oral contraceptive use, the type of estrogen used, or the years in which oral contraceptives were used. The mean duration of oral contraceptive use was 30.9 months by the case subjects and 30.2 months by the control subjects.

Adolescent↗
PubMed1977

Some observations on the value of endocervical curettage performed as an integral part of colposcopic examination of patients with abnormal cervical cytology.

A total of 259 patients underwent endocervical curettage as an integral part of colposcopic examination of patients with abnormal cervical cytology. The transformation zone was entirely visualized in 140 patients (54.1 per cent), and, in 8.6 per cent of this group, the endocervical curettings were abnormal. On no occasion did the endocervical curettage harbor the worst lesion when compared to the histology of the ectocervical biopsy, cone biopsy, and hysterectomy specimens. In 117 patients (45.2 per cent), the transformation zone could not be visualized in its entirety, and in 57.3 per cent the endocervical curettings were abnormal. In one patient of this group invasive carcinoma was present in the endocervical curettage, and in another patient invasive carcinoma was present in both the ectocervical biopsy and the endocervical curettage. Thus, when the entire transformation zone is not visualized in its entirety or at all, endocervical curettage appears to be of value since a frank invasive carcinoma may be diagnosed and a cone biopsy avoided.

Biopsy↗
PubMed1977

Evaluation of a carbamate-impregnated flea and tick collar for dogs.

To acquire information regarding the potential hazard of pesticide-impregnated collars to dogs, 13 male Beagles were allotted to 2 groups; 8 of the dogs were fitted wtih propoxur-impregnated tick and flea collars and the other 5 were fitted with placebo collars. All dogs wore their collars for 42 consecutive days. The dogs wearing test collars had significant (P less than 0.01) depression of erythrocyte and plasma cholinesterase activities at day 1 after collar application; however, the enzyme activity values returned to the preexposure range within 3 days. Miosis, with decreased pupillary response, was noticed during the 1st week of exposure. Irritation of the skin of the neck was mild and transient in both the test and control groups from the 2nd week onward.

Animals↗
PubMed1977

Incidence, significance, and follow-up of para-aortic lymph node metastases in late invasive carcinoma of the cervix.

One hundred and four patients with Stages II and III of cervical carcinoma underwent para-aortic node biopsies. Of these, 12.5 per cent of patients with Stage IIA, 14.9 per cent of patients with Stage IIB, and 38.4 per cent of patients with Stage III carcinoma of the cervix had positive para-aortic nodes. They subsequently recieve 6,000 rads to the para-aortic area. The radiotherapy complication rate was high. Within four years, 50 per cent of the patients with positive para-aortic nodes had other distant metastases. The two- and four-year follow-up is presented. Only one of 13 patients with positive para-aortic nodes was alive at the end of four years.

Aorta, Abdominal↗
PubMed1977

Plasma ribonuclease: a marker for the detection of ovarian cancer.

There were no significant differences between the mean blood plasma (leukocyte-free) RNAase activity among 128 healthy women volunteers age 13-70 and 49 women with benign gynecological tumors. Exceptions to this finding were three apparently healthy women volunteers who had plasma enzyme activity which was higher than two standard deviations from the mean of the control subjects. Increased plasma RNAase activity was also demonstrated for 21 of 22 patients with ovarian carcinomas of differential histological types. This group included two patients with Stage IA, two patients with Stage IC ovarian carcinoma, and 17 patients with advanced ovarian carcinoma. The one exception was a patient with a well encapsulated, mucinous cystadenocarcinoma, Stage IA. The plasma RNAase activity returned to normal values in all of the cancer patients who had no clinical evidence of residual malignant tissue after surgical treatment. However, the enzyme activity also returned to a normal value in one of the 17 women in whom all of the malignant tissue was not removed. These data indicate that plasma RNAase activity can be utilized as a tumor marker for the presence of ovarian malignancies of various histological types, and to differentiate between malignant and benign neoplasms.

Female↗
PubMed1977

Priapism: evolution of management in 48 patients in a 22-year series.

The choice of an effective method to treat priapism is challenging because precise causes in the majority of patients have not been well defined. A review of 48 patients treated during a 22-year period shows evolution of a regimen of management that has yielded a high percentage of success. Idiopathic priapism and sickle cell disease accounted for 81 per cent of the subjects. An evaluation should include a medication history, a search for specific diseases, as well as a thorough physical examination to detect possible etiologic factors. The explanation for the frequent association of fever deserves further investigation. Initial therapy consisting of aspiration and irrigation, and intermittent pneumatic cuff compression should be undertaken for a trial period of 12 to 36 hours, repeating the aspiration 2 or 3 times if necessary. The failure of priapism to resolve after such treatment is an indication for a shunt operation. Patients with known etiology should be treated specifically for the primary disease and usually more conservatively for priapism. Resolution occurred in all patients and approximately 50 per cent regained sexual potency.

Adolescent↗
PubMed1977

Pregastric esterase and other oral lipases--a review.

The secretion of pregastric esterase and other oral lipases has been detected in 13 species. Research on secretion by the human, calf, kid goat, lamb, and rat of pregastric esterase has been significant. Secretion by calves is little affected by age or diet but is greater when calves are nipple fed than when pail fed. Whole milk sham-fed to calves exhibits immediate, sharp decreases in pH and rennet coagulation time resulting from liberation of free fatty acids by pregastric esterase. Bacterial counts in sham-fed products are higher than in control (nonfed) products, but during subsequent incubation bacterial numbers increase less rapidly in sham-fed products. Calf pregastric esterase is a major fat digestive enzyme in young calves but gradually becomes subsidiary to pancreatic lipase as secretion of the latter develops with age. Calf, kid goat, and lamb pregastric esterase exhibits optimum activity on milk fat but is capable of splitting other dietary fats. Data on oral and "gastric" lipases in calves, humans, and rats suggests that gastric lipase is oral lipase. Data on pH and temperature optima as well as activation and inhibition of oral lipases is contradictory but appears to vary considerably between species. Calf pregastric esterase exhibits a unique specificity for fatty acids 4:0 to 10:0 and preferentially hydrolyzes the primary ester position of glycerin. Preparations of calf, kid goat, and lamb pregastric esterase are used commercially to impar typical flavors to Italian-type and Feta cheeses and to accelerate flavor development in other cheeses and cheese-like products. Butterfat modified by pregastric esterase is utilized to impart dairy flavor character to a wide range of processed foods. Treatment with pregastric esterase of calf scours and human malabsorption of syndrome also has been reported.

Abomasum↗
PubMed1976

Ureterovaginal fistula as a complication of radical pelvic surgery.

The main objection to radical hysterectomy and pelvic node dissection as a method of primary treatment for cervical carcinoma is the inherent danger to the ureters that may result in ureterovaginal fistula formation. The purpose of this paper is twofold: (1) to show that with adoption of certain surgical and clinical measures our incidence of fistula formation has been significantly reduced, and (2) to discuss the management of ureterovaginal fistula when it occurs.

Female↗
PubMed1976

The barrel-shaped cervical carcinoma.

Twelve patients had barrel-shaped cervical carcinoma among 493 new patients with primary invasive cervical carcinoma, at the Downstate Medical Center, New York from January, 1964 to December, 1972. The incidence of barrel-shaped lesions among invasive carcinoma of the cervix was 2.43%. All 12 patients were treated with external radiation to the whole pelvis followed by two radium applications. In six patients an extrafascial hysterectomy was performed 6 to 12 weeks after radiation. Six patients died and six survived (50%). Six patients survived for over 2 years after therapy with no evidence of recurrence. Of these, four are alive and well for over 5 years. All six patients died within 20 months after therapy. The barrel-shaped cervical carcinoma fared poorly (six deaths among 12 patients or 50%) when compared with the over-all Stage I and Stage II cervical carcinoma (87 deaths among 339 patients or 25.5%).

Adult↗
PubMed1976

Diagnosis and management of microinvasive (stage IA) carcinoma of the uterine cervix.

One hundred and sixty-two cases of Stage IA microinvasive carcinoma of the cervix are presented. These patients represent the combined experience at the University of Miami School of Medicine, Miami, Florida, and Downstate Medical Center, Brooklyn, New York. The criteria used in both institutions are 1) penetration of invasive carcinoma beneath the basement membrane of less than 1 mm and 2) absence of invasion of blood vessel or lymphatic spaces. All tissue specimens have been measured accurately by use of calibrated optics. The literature has been reviewed for criteria of diagnosis of microinvasive cancer, as well as methods of management. Our method of accurately determining depth of penetration is described and the evolution of microinvasive cancer is presented in a series of photomicrographs in which measurements are accurate to 0.1 mm. In the literature, when depth of penetration of up to 5 mm is used as criterion for microinvasive carcinoma, the incidence of nodal metastasis may be as high as 3.5%. Since, in our combined institutions, the mortality rate with radical hysterectomy is less than 1% and the incidence of ureterovaginal fistulas is 1.2%, we conclude that simple hysterectomy is not adequate therapy for lesions with stromal invasion to a depth of 5 mm.

Biopsy↗