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Biomedical subjects

J T Johnson

Publications and source records attributed to J T Johnson.

At least 163 records · Page 9Linked to original sources
PubMed1991

Factors influencing success of dietitians employed in business and industry.

Career opportunities in business and industry have been identified as one area of growth for the dietetics profession. The purposes of this study were to identify the skills, attributes, and knowledge areas dietitians need to succeed in business and industry; ascertain methods used to acquire these; assess factors that influenced career change; and determine the degree of perceived adequacy of academic preparation by practitioners employed in business and industry. A questionnaire, developed on the basis of a Delphi study involving 21 dietitians employed in business and industry, was administered to a national sample of 387 members of the Dietitians in Business and Industry (DIBI) dietetic practice group who were employed in business and industry. The overall response rate was 299 (77%); respondents were from 39 states. Skills, attributes, and knowledge areas were identified for specific employment classifications in business and industry. Self-motivation and work experience in business were identified as the most important methods for acquiring skills for this area of practice. Challenge of a new position and diversity of job responsibilities had the most influence on career change of respondents. Undergraduate and graduate education were rated somewhat inadequate and adequate, respectively, by the majority of respondents. The findings indicate that positions in business and industry require specific skills, attributes, and knowledge that may not necessarily be attained through traditional approaches. Self-assessment and appropriate self-development activities are essential for success.

Career Choice↗
PubMed1990

The absence of lymphoid suppressor cells in tumor-involved lymph nodes of patients with head and neck cancer.

Patients with head and neck cancer often have decreased local or regional immunocompetence. Lymphocytes obtained from tumor-involved or -uninvolved lymph nodes (LNL) of these patients showed low or undetectable levels of antitumor cytotoxicity and low proliferative responses in vitro to interleukin 2 (IL2) or mitogens in comparison to peripheral blood lymphocytes (PBL). Lymphokine-activated killer (LAK) cell activity of LNL was lower (P less than 0.05) than that of autologous PBL. Fresh LNL were neither enriched in cells with the CD8+ CD11b+ "suppressor" phenotype nor did they suppress proliferative or cytotoxic responses of autologous PBL in mixing experiments. LNL did not inhibit LAK cell generation from autologous PBL in the presence of IL2. Also, no evidence for the inhibition of autotumor-restricted responses by IL2-activated LNL was obtained. Spontaneous or in vitro-induced production of IL1 beta. TNF alpha, and IFN-tau was low or undetectable in LNL from tumor-involved and -uninvolved lymph nodes in comparison to that in normal or autologous PBL. Mitogen-induced IL2 production was normal in LNL. The depressed ability to produce certain cytokines may be in part responsible for a state of unresponsiveness present in lymph nodes obtained from patients with head and neck cancer. No evidence for the presence of lymphoid suppressor cell in LNL of these patients was obtained.

Aged↗
PubMed1990

Local adoptive immunotherapy of human head and neck cancer xenografts in nude mice with lymphokine-activated killer cells and interleukin 2.

The efficacy of local adoptive immunotherapy with human lymphokine-activated killer cells and recombinant interleukin 2 (rIL-2) in growth inhibition of established squamous cell carcinoma of the head and neck (SCCHN) was evaluated in a nude mouse model. The model of xenografted SCCHN was established by s.c. injections of in vitro maintained tumor cells (2-10 x 10(6) cells/mouse) into the flank of splenectomized animals pretreated with cyclophosphamide (200 mg/kg). The SCCHN line used was tumorigenic in 95% of the appropriately conditioned nude mice. Inhibition of tumor growth by locally administered effector cells was the end point of the study, since the tumors did not metastasize within 6 weeks of tumor challenge. Either i.p. or local administration of rIL-2 alone (1000 units/day) to the tumor site daily for 2 weeks resulted in a significant inhibition of tumor growth. In the absence of detectable natural killer activity in these mice, a modest dose of rIL-2 had a direct antitumor effect on SCCHN cells in vivo. In addition, complete inhibition of tumor growth was achieved with 3 times weekly injections of 5-10 x 10(6) lymphokine-activated killer cells delivered to the tumor site and 1000 units of rIL-2 administered locally every day for 2 weeks. Our data indicate that local or systemic immunotherapy with rIL-2 alone or local adoptive immunotherapy with an adequate dose of lymphokine-activated killer cells plus rIL-2 may be effective in preventing the growth of established SCCHN tumors in vivo.

Animals↗
PubMed1990

A comparison of male rat and human urinary proteins: implications for human resistance to hyaline droplet nephropathy.

alpha 2u-Globulin (alpha G), the major urinary protein of sexually mature male rats, is a key determinant of susceptibility to hyaline droplet nephropathy (HDN) induced by a variety of hydrocarbons in male rats. Arguments against extrapolating renal toxicity and carcinogenicity data for HDN-inducing toxicants from male rats to risk assessment for humans rely on the observation that humans do not express alpha G. Yet, human serum and urine are known to contain proteins coded for by the same gene family that also controls alpha G synthesis in the rat. Therefore, to understand some of the quantitative and qualitative differences between proteins of human and male rat urine which confer apparent resistance to HDN in humans, urinary proteins of male F344 rats (ca. 3 months old) and normal human males were compared by cation exchange, gel filtration, SDS-PAGE, and partially identified by Western blotting. We observed that (1) the protein content of human urine is only 1% that of male rat urine; (2) human urinary proteins, recovered by (NH4)2SO4 precipitation followed by dialysis, are primarily of high (greater than or equal to 75 kDa) molecular weight (MW) with minor components of 12-66 kDa; (3) male rat urine has little high-MW protein, but is rich in alpha G (18.5 kDa); (4) at pH 5, the most cationic fraction of human urinary protein constituted only about 4% of the total while the analogous fraction of rat urine, containing alpha G, contained 26% of total urinary protein; and (5) cationic (at pH 5.0) human urinary proteins included small amounts of proteins, e.g., alpha 1-acid glycoprotein, and alpha 1-microglobulin, which are products of the gene family coding for alpha G in rat. Thus, although humans excrete trace amounts of proteins similar to alpha G, the very low protein content of human urine, the relatively small proportion of cationic to total proteins, and the high MW of the most abundant human urinary proteins form a biological basis for suggesting that humans are not at risk for the type of fuel and solvent hydrocarbon-induced nephropathy, and the sequelae of such nephropathy, observed in male rats.

Adult↗
PubMed1990

Defluorination of 1,1,1,2-tetrafluoroethane (R-134a) by rat hepatocytes.

As part of its toxicological evaluation we assessed the in vitro metabolism of 1,1,1,2-tetrafluoroethane (R-134a), a non-ozone-depleting chemical likely to replace dichlorodifluoromethane (R-12) as an air-conditioning refrigerant. Hepatocyte suspensions in sealed flasks produced increasing quantities of F- (detected in the liquid media) as the headspace concentration of R-134a increased from 1% to 50% (balance of atmosphere 95% O2-5% CO2); the kinetics of defluorination suggested substrate-saturation. Little F- was detected in cultures without R-134a or in cell suspensions heated prior to addition of R-134a. Halothane (1,1,1-trichloro-2-bromo-2-chloro-ethane), although not defluorinated by hepatocytes maintained with 95% O2, inhibited defluorination of R-134a. Hepatocytes from phenobarbital-treated rats dehalogenated high (greater than or equal to 25%) concentrations of R-134a at greater rates than cells from untreated rats. These findings are consistent with the hypothesis that oxidative metabolism of R-134a by cytochrome P-450 can occur in vivo.

Animals↗
PubMed1990

Neutropenic enterocolitis. A new complication of head and neck cancer chemotherapy.

Neutropenic enterocolitis is a recognized complication of immunosuppression or chemotherapy for leukemia. It presents as severe abdominal pain and tenderness, fever, and diarrhea associated with granulocytopenia. Gastrointestinal symptoms associated with chemotherapy for head and neck neoplasms include nausea and emesis, but not acute abdominal distress. We present, to our knowledge, the first case of neutropenic enterocolitis in a patient receiving cisplatin and fluorouracil chemotherapy for metastatic head and neck cancer.

Agranulocytosis↗
PubMed1990

Extramedullary plasmacytoma of the thyroid associated with a serum monoclonal gammopathy.

Extramedullary plasmacytoma is a malignant plasma cell dyscrasia that is most commonly found in the head and neck. Progression to disseminated disease in the form of multiple myeloma occurs in 17% to 32% of cases. Herein, we describe a patient with extramedullary plasmacytoma of the thyroid gland in whom a serum monoclonal gammopathy resolved with surgery and irradiation of the primary. Although rare, this diagnosis should be considered in patients presenting with obstructive thyromegaly and autoimmune thyroiditis.

Aged↗
PubMed1990

Modulation of glucose metabolism in isolated rat hepatocytes by 1,1,1,2-tetrafluoroethane.

The thermodynamic behavior and lack of ozone-depleting potential of 1,1,1,2-tetrafluoroethane (R-134a) suggest it as a likely replacement for dichlorodifluoromethane (R-12), now used as the refrigerant in many air-conditioning systems. To further the presently incomplete toxicological analysis of R-134a, the effects of R-134a on cell viability and functional competence of glucose metabolism were evaluated in suspension cultures of hepatocytes derived from fed or fasted rats. R-134a concentrations up to and including 75% (750,000 ppm) in the gas phase of sealed culture flasks did not produce evidence of cytolethality (LDH leakage) following 2 hr of exposure; in contrast, halothane (1,1,1-trifluoro-2-bromo-2-chloroethane) caused cell death at a gas phase concentration of only 1250 ppm. In hepatocytes isolated from fed rats. R-134a at concentrations of 12.5 to 75% increased glycolysis (production of lactate + pyruvate) in a concentration-dependent manner; no effect was observed at 5%. At 25%, R-12 and 1,1,2,2-tetrafluoro-1,2-dichloroethane (R-114) were of equal potency to R-134a in stimulating glycolysis: 1,1,1,2,2-pentafluoro-2-chloroethane (R-115) depressed glycolysis slightly. Halothane, at concentrations as low as 300 ppm, markedly increased rates of glycolysis. Glucose production by hepatocytes of fed rats was decreased by R-134, R-12, and R-114 only at concentrations of 25% or more. On the other hand, halothane (greater than or equal to 300 ppm) potently decreased glucose production by hepatocytes. In cells isolated from livers of fasted rats, R-134a exposure inhibited gluconeogenesis in a concentration-dependent manner although this effect was not significant until R-134a concentrations reached 12.5%. Comparative potency studies showed that R-134a, R-12, or R-114 (25% gas phase) inhibited gluconeogenesis about equally while as little as 300 ppm halothane was effective and R-115 (25%) was without effect. Considering that the threshold for alteration of the rate of glucose metabolism in this in vitro paradigm is about 12.5% R-134a, we conclude that toxicologically significant alteration of glucose-linked bioenergetics is unlikely at the levels of R-134a exposure anticipated in workplace or environment.

Animals↗
PubMed1990

Peritonsillar abscess. Why aggressive management is appropriate.

Peritonsillar abscess is the most common deep neck infection in adults. Infections develop from purulent material collecting in the fascial spaces lateral to the capsule of the palatine tonsil. Infections are usually polymicrobial, and a significant number of anaerobes are isolated. The cornerstone of therapy is drainage of the abscess. With cooperative patients, careful permucosal needle aspiration is an accepted method of primary therapy. Large or recurrent abscesses require otolaryngologic consultation for adequate incision and drainage. Tonsillectomy may be necessary to prevent re-formation of abscess in patients with a history of recurrent tonsillitis.

Adult↗
PubMed1990

Inhaled particle retention in rats receiving low exposures of diesel exhaust.

To study the effects of a low concentration exposure on the retention and clearance of submicron particles from the lungs, we exposed male Fisher 344 rats to diesel exhaust diluted to 50 micrograms diesel exhaust particles (DP)/m3, 20 h/d, 7 d/wk for 52 wk. Lung burdens (amount of DP in lungs) and the alveolar macrophage burdens were measured up to 52 wk postexposure. By 1 yr postexposure at least 80% of the DP was eliminated from the lungs and similarly cleared from the lavaged pool of macrophages. The DP remaining in the lungs was observed in alveolar, parabronchial and paravascular maculae. In contrast to previous high concentration exposure studies, only trace amounts of particles were observed in the mediastinal lymph nodes. To study the concentration dependence of particle retention, rats were exposed to equivalent exposures of 18 d x mg DP/m3 delivered at 5700 micrograms/m3 for 3 d, 1600 micrograms/m3 for 12 d, 250 micrograms/m3 for 72 d, or 50 micrograms/m3 for 365 d. Higher lung and macrophage burdens were initially achieved with the brief, high concentration exposures. During the postexposure period, animals exposed to the higher concentrations cleared more of the lung burden. Exposure to lower concentrations resulted in higher long-term lung burdens. These results are consistent with a model of lung clearance in which the macrophage burden and the duration of exposure are both important to the formation of the maculae. In a brief high concentration exposure, the macrophage burden rises rapidly, but then declines rapidly. However, in longer low concentration exposures, the macrophage burden will not reach the same peak, but stays at intermediate levels during the exposure and stimulates a steady development of the lung maculae from particle-laden macrophages leaving the active pool of pulmonary phagocytes.

Animals↗
PubMed1990

A surgeon looks at cervical lymph nodes.

Squamous cell carcinoma is the most commonly encountered malignant neoplasm of the upper aerodigestive tract. The most important factor that influences therapeutic outcome is the development of metastasis to the cervical lymph nodes. Traditionally, assessment and staging have been based on clinical evaluation. Studies of clinicopathologic correlation have demonstrated that both the sensitivity and the specificity of the clinical examination findings are unsatisfactorily low in that false-negative rates may be 15%-25% while false-positive rates may be similarly high. The clinician is caught in the position of having to overtreat many patients to avoid undertreating a few. The rapid advances in imaging technology introduced in the past decade have greatly affected our ability to identify cervical metastatic disease. With improved technology and increased experience, patients can be better characterized individually according to the status of the cervical lymph nodes so that therapeutic intervention can be appropriately designed.

Carcinoma, Squamous Cell↗
PubMed1990

Exercise tolerance during nasal cannula and transtracheal oxygen delivery.

Previous studies have reported that exercise tolerance improves with transtracheal oxygen delivery. However, patients were not blinded to the delivery technique used, introducing a potential source of bias. The purpose of this study was to compare exercise tolerance during nasal cannula and transtracheal delivery using a randomized double-blinded technique. Subjects (n = 11) performed 12-min walks on the same day while receiving nasal cannula and transtracheal delivery. Nine of 11 subjects walked farther with transtracheal delivery, a significant increase (p less than 0.01). Mean increase in walk distance was 95 +/- 86 feet. In addition, a trend was seen toward greater improvement in walk distance with greater flows through the catheter (r = 0.58, p less than 0.06). Time into the walk when desaturation (SaO2 less than 90%) first occurred was not significantly different. We conclude that exercise tolerance improves when oxygen is delivered by transtracheal catheter. This improvement is unrelated to an increase in SaO2. We speculate that the increase in exercise tolerance may be related to other physiologic effects of flow through the catheter.

Aged↗
PubMed1990

Supraglottic carcinoma: patterns of recurrence.

A retrospective review of 202 patients with supraglottic squamous cell carcinoma and at least 2 years of follow-up was performed. Surgery alone was used to treat 102 patients, and combined therapy in 100 patients. Local-regional failure occurred in 47 (23%) patients. Only 4 patients (2%) developed recurrence at the primary site. The neck was the most common site for recurrent disease (39/47 or 83%), which in 35 patients appeared in the undissected, contralateral side. The risk to the contralateral side of the neck in patients with midline (epiglottic) lesions was similar to that in those with unilateral (aryepiglottic fold) lesions. Supraglottic laryngectomy, when properly selected, did not compromise primary control in the larynx. Radiation therapy was ineffective in controlling metastasis to the contralateral side of the neck in 16 of 99 patients (16%). Therefore, routine bilateral neck dissection should be considered in the surgical treatment of supraglottic carcinoma for control of regional disease.

Adult↗
PubMed1990

Jejunal interposition for repair of stricture or fistula after laryngectomy.

Complications following total laryngectomy may include pharyngocutaneous fistula or pharyngeal stricture. Traditional techniques of repair of fistula and stricture with local or regional flaps lead to a high rate of failure. In this study, we report 18 patients treated by secondary jejunal interposition (JI) to rehabilitate swallowing following recalcitrant postlaryngectomy stricture or fistula. All patients had undergone total laryngectomy with or without partial pharyngectomy for treatment of squamous cell carcinoma of the larynx (8) or hypopharynx (10). Four were stage II; 5, stage III; and 9, stage IV. Thirteen patients (72%) regained swallowing function. Complications of secondary JI included perioperative death (2), flap loss (1), and persistent fistulas (3). Jejunal interposition may be the best modality in the rehabilitation of swallowing in patients with persistent fistula or stricture that fails to respond to traditional management.

Aged↗
PubMed1990

Medical complications in total laryngectomy: incidence and risk factors.

The prevention and management of medical complications are important components in the surgical treatment of head and neck malignancies. We retrospectively evaluated the postoperative medical complications in 414 patients who underwent total laryngectomy between 1973 and 1987. The mortality rate was 1.2% (five deaths); while major, nonfatal medical complications occurred in 6.3% (24 of 384 patients)--seven strokes, three myocardial infarctions, two pulmonary emboli, and 12 respiratory failures requiring mechanical ventilation. Elderly patients did not experience more frequent or more severe medical complications, and the overall pattern of complications was different from that of other surgical specialties. Only specific cardiovascular and pulmonary risk factors were associated with these complications. We conclude that medical complications are a significant cause of morbidity in total laryngectomy; a focused preanesthetic risk factor analysis by a medical team familiar with head and neck cancer patients assures prompt identification and management of these complications.

Adult↗
PubMed1990

Hemilaryngectomy for salvage of radiation therapy failures.

Radiation therapy has been the treatment most frequently used for early vocal cord cancer with surgery usually in the form of total laryngectomy held in reserve as a salvage option. We report our experience in selected patients who, having failed radiation therapy for their early vocal cord cancers, underwent frontolateral hemilaryngectomy as attempted salvage surgery. Between 1977 and 1986, fourteen patients at the University of Pittsburgh Eye and Ear Hospital underwent hemilaryngectomy for salvage of their stage I vocal cord squamous cell carcinoma after full-course radiation therapy had been unsuccessful. Over this same time period, 77 patients underwent total laryngectomy for salvage of radiation therapy failure. Three patients failed hemilaryngectomy, two of whom were ultimately salvaged with total laryngectomy. Thus a 79% salvage rate was achieved with hemilaryngectomy with an average followup of 90 months. The overall cure rate was 93% (13 of 14) with voice preservation in 86% (12 of 14). Decannulation, postoperative infection, and initiation of oral intake were not influenced by age. Such problems occurred more often in patients undergoing radiation therapy compared to those undergoing hemilaryngectomy without previous radiation therapy. These results indicate that hemilaryngectomy may be used for the salvage of radiation therapy failures of stage I vocal cord carcinoma with good success and without undue morbidity.

Aged↗
PubMed1990

Stomal recurrence after laryngectomy: interrelated risk factor study.

This study was designed to identify pathogenic factors in recurrent carcinoma at the tracheal stoma. The charts of 444 patients with laryngeal cancer who were treated surgically between 1976 and 1988 revealed stomal recurrence in 15 (3.4%). Eighty percent of the patients with stomal recurrence had tumors in the subglottis. In comparison to patients with different sites involved this was significant (p less than 0.001). Other variables examined and analyzed included primary stage, previous treatment, neck pathologic status, neck treatment, age, sex, postoperative adjunctive therapy, and timing of tracheotomy. Tumor involvement of the subglottis is the single most important variable in stomal recurrence of carcinoma. Previous conservation laryngeal surgery and preoperative/emergency tracheotomy are not related to stomal recurrence of carcinoma. Mean length of survival for patients with stomal recurrence of carcinoma in our series was 8.9 months. Two patients were successfully treated with extensive surgical resection. The dismal prognosis of stomal recurrence of carcinoma suggests that management of this condition should focus on prevention. Treatment of patients with tumors of the subglottis should include attention to the paratracheal region and superior mediastinum, in conjunction with laryngectomy immediately after initial diagnosis.

Adult↗