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Biomedical subjects

J R Cohn

Publications and source records attributed to J R Cohn.

At least 37 records · Page 2Linked to original sources
PubMed1989

Persistent severe asthma in an adult from transient dog exposure: a brief communication.

While atopy is commonly found without signs of asthma, it has been proposed that in some settings, allergen exposure itself can lead to the development of the asthmatic diathesis. To date, this theory has been primarily supported by cases of occupational asthma, where prolonged symptoms have persisted following termination of exposure to the suspect allergen. This model is complicated by associated medicolegal implications, as well as by the generally long-term nature of the exposure, raising questions about the concurrent natural history of a given patient's illness. We report a case of non-occupational dog dander-induced asthma. Exposure was on an intermittent basis over a 15-month period, with the patient exhibiting a classic late phase response. Following discontinuation of exposure to dog dander, he continued to have symptoms, considerably in excess of his findings prior to dog dander exposure.

Adult↗
PubMed1987

Obstructive emphysema due to mucus plugging in quadriplegia.

A quadriplegic patient with obstructive emphysema caused by mucus in the bronchi of the hyperinflated lung, demonstrated by chest radiograph and corrected by bronchoscopic aspiration of secretions from the hyperexpanded side, is reported. Subsequently, this phenomenon recurred in the opposite lung. This case is of particular interest, as it is the only documented report of obstructive emphysema due to mucus plugging in an adult with grossly normal airways. This case contrasts markedly with the usual picture of atelectasis and lobar or segmental collapse observed with large airway obstruction by mucus in this setting.

Adult↗
PubMed1985

Rifampicin-induced renal failure.

Renal failure is a rare complication associated with the use of rifampicin for the treatment of tuberculosis, usually occurring well into the course of therapy. The following is a report of 2 cases of rifampicin-induced renal insufficiency. In the first case oligo-anuric renal failure occurred on the thirteenth day of treatment, after the patient had taken only 9 doses of medication. The second case occurred in a patient who developed renal failure while on daily therapy in the hospital. A literature review revealed 83 other reported cases of rifampicin-induced renal insufficiency. Intermittent or interrupted therapy appears to be a significant risk factor for the development of this complication.

Acute Kidney Injury↗
PubMed1985

Localized bronchomalacia presenting as worsening asthma.

A patient with longstanding mild asthma presented with a several month history of almost continuous wheezing. Pulmonary function tests suggested large airway variable intrathoracic obstruction. At bronchoscopy, she was found to have severe bronchomalacia limited to the left main bronchus. There was almost complete obstruction of that airway during forced expiration.

Asthma↗
PubMed1984

Reactivity to spherule-derived coccidioidin in the southeastern United States.

Delayed hypersensitivity skin tests with mycelium-derived (coccidioidin) or spherule-derived (spherulin) antigens (or both) can be used to identify patients who have been sensitized to the dimorphic fungus Coccidioides immitis. Prior studies suggest that coccidioidin and spherulin skin test antigens detect comparable numbers of reactors among exposed subjects. Studies in subjects residing in areas outside the United States where C. immitis is not endemic suggest that both antigens are specific for the fungus. The specificity and reactivity of coccidioidin and spherulin have not been compared in nonendemic regions of the United States in which the skin test antigens and an appropriate travel or exposure history are used to identify patients with possible C. immitis infection. A review of delayed cutaneous reactions to coccidioidin in 6,375 patients tested between 1970 and 1979 in the southeastern United States revealed 958 (15.0%) and 234 (5.7%) positive reactions (greater than or equal to 5 mm), respectively, at 24 and 48 h. Subsequent tests with spherulin in 2,775 patients tested in 1980 and 1981 revealed 866 (31.2%) and 288 (10.3%) positive reactions, respectively, at 24 and 48 h. False-positive immediate hypersensitivity reactions contributed to the large number of spherulin reactors at 24 h. Differences among the patients sampled, work exposure, and travel history were excluded as causes of this surprising and highly significant (P less than or equal to 0.0001) difference in the 48-h delayed cutaneous reaction. These observations suggest two possibilities: (i) spherulin is less specific than coccidioidin, or (ii) a surprising prevalence of C. immitis sensitization exists among patients in nonendemic regions of the United States.

Antigens, Fungal↗
PubMed1984

Simplified screening for immune complexes by laser nephelometry of ultracentrifuged serum.

Serum samples were drawn from 14 healthy volunteers after an overnight fast and again after a meal. Each sample was divided into two aliquots. One aliquot was centrifuged at 20,000 rpm for 20 min, and a portion from the middle of the tube was removed by puncturing the tube's side. All samples were then added to cuvettes containing 0.14 M NaCl alone or 1, 2, 3, or 4% polyethylene glycol in 0.15 M KCl. The light scattering of each tube was measured. The centrifuged samples scattered 58% less light than the uncentrifuged controls. The range of values obtained with the centrifuged samples was also smaller as reflected in the standard deviation of the means obtained at each polyethylene glycol concentration. The coefficient of variation for replicate samples ranged from 0 to 16.6% (mean 5.8%), even when samples were processed differently. Storage at -70 degrees C significantly increased light scattering compared to baseline values. Serum samples were drawn from 44 patients with diseases that have been associated with immune complexes. Nephelometry selectively identified some groups of patients as abnormal. We conclude that preparative ultracentrifugation removes much of the background light scattering of serum samples, including that due to lipid, under conditions that do not sediment out immune complexes. Because it measures a physical property of immune complexes, this assay may provide information that is not available from biological receptor-based assays.

Adult↗
PubMed1983

A quantitative examination of the light scattering properties of immune complexes in polyethylene glycol.

The effect of polyethylene glycol on the light scattering properties of immune complexes prepared in vitro was examined. Immune complexes were prepared in the zone of antigen excess from purified rabbit anti-ovalbumin and ovalbumin at 2-32 times (X) the equivalence ratio. Immune complex concentration was determined by analytical ultracentrifugation. Immune complexes were then incubated for 1 h in solutions containing 0, 1, 2, 3 and 4% polyethylene glycol (PEG), and examined in a laser nephelometer. The effect of PEG on light scattering (%RLS) was different for each immune complex combining ratio, although for each immune complex combining ratio, there was a linear relationship between the light scattered and immune complex concentration. To evaluate the effect of serum proteins on the light scattered by the immune complexes, immune complexes made at 4X and 16X the equivalence ratio were placed in serum and the sera containing these immune complexes were examined in the nephelometer. The ratio of the %RLS of the immune complexes in serum to the sum of the %RLS of the same immune complexes in saline plus the %RLS of serum alone was determined. This ratio varied systematically with changes in combining ratio and PEG concentration, as well as the concentration of the immune complexes themselves. Depending on the combination of these 3 factors, serum could increase, decrease or have no effect on the quantity of light scattered by the immune complexes. Discrimination between serum alone and serum containing immune complexes was best in 3% PEG.

Animals↗
PubMed1983

The relationship between cutaneous cellular immune responsiveness and mortality in a nursing home population.

The survival over 18 months of 29 nursing home residents was compared with results of cutaneous testing of cell-mediated immunity at the start of the period of observation. Eight antigens were used to evaluate immunity by intradermal injection of each antigen and measurement of the areas of induration at 48 and 72 hours. A difference in responses was seen between the survivors and those who died, although this difference was statistically significant at 72 hours only. As expected, survivors had more (3.1, compared with 1.47) and larger (8.6 mm, compared with 3.2 mm) reactions at 72 hours than those who died.

Aged↗
PubMed1983

Persistent cutaneous cellular immune responsiveness in a nursing home population.

Mantoux-type skin tests were applied to 29 elderly residents of an intermediate care floor of a nursing home. Eight antigens were used with each resident, and the size of the reactions was measured at 6, 24, 48, and 72 hours. All but one resident had at least one response greater than or equal to 3 mm at 48 or 72 hours, and most had more than one response of that size. At 48 compared with 72 hours, there was one more responder and the mean size of the reactions to each antigen was greatest. However, there were two responders at 72 hours who did not react at 48 hours, and the total number of reactions in the group was greater at the later reading. Only one resident did not produce any response at either 48 or 74 hours. The minimum number of antigens needed to identify all responsive subjects was five (PPD-Avian, coccidioidin, histoplasmin, streptokinase-streptodornase, and trychophytin). The purified protein derivative of tuberculin skin test was repeated on subjects who had an initial response less than 10 mm, and one increase of more than 6 mm was observed in a resident who was initially unresponsive to that antigen.

Aged↗
PubMed1980

In vitro antagonism by erythromycin of the bactericidal action of antimicrobial agents against common respiratory pathogens.

Ten strains each of Staphylococcus aureus, Haemophilus influenzae, Enterobacter spp., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, and Streptococcus pneumoniae were tested in vitro against erythromycin combined with ampicillin, cefamandole, or gentamicin. Antagonism by erythromycin occurred with 47% of the combinations involving strains of S. aureus and to a lesser degree with H. influenzae. Synergy occurred most commonly with H. influenzae (27%). The high frequency of antagonism and synergy with these organisms was associated with a broad range of bacteriostatic action by erythromycin against these same bacteria. The implications for the treatment of pneumonia are discussed.

Ampicillin↗
PubMed1977

Protective action of timolol in acute myocardial ischemia.

Timolol, a beta-adrenoceptor blocking agent with little or no cardiodepressant activity, was studied in acute myocardial ischemia in cats. Timolol, at a dose of 25 mug/kg, blocked 75 to 80% of the cardiac response to isoproterenol. This dose also significantly reduced heart rate in cats subjected to acute myocardial ischemia by ligation of the left coronary artery. Timolol significantly prevented the spread of ischemic damage in the myocardium as assessed by (a) curtailing the increase in plasma creatine phosphokinase (CPK) activity, (b) preventing the loss of CPK from the ischemic portion of the myocardium, and (c) restoring the elevated S-T segment of the electrocardiogram toward normal. Timolol did not significantly retard the increase in fragility of lysosomes in ischemic myocardial tissue. The mechanism of the protective effect to timolol on the ischemic myocardium appears to be via reducing myocardial oxygen demand by decreasing heart rate.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Osteoradionecrosis of the head and neck: a case of a clavicular-tracheal fistula secondary to osteoradionecrosis of the sternoclavicular joint.

Radiation therapy is an integral part of treatment for head and neck cancer, but its use is not without complications. We describe the first reported sternoclavicular-tracheal fistula resulting from osteoradionecrosis (ORN) at the medial clavicle. This ORN resulted from definitive radiation therapy for a primary pyriform sinus squamous cell carcinoma. The diagnosis of ORN was made by fiberoptic bronchoscopy. The physiologic damage of ORN is based on a compromised blood supply and altered metabolism of bone formation secondary to effects of ionizing radiation. Treatment requires meticulous hygiene, antibiotics, and debridement as conservative therapy. Radical surgery and reconstruction may be indicated in refractory cases. A thorough preirradiation assessment of patients is mandatory to decrease the incidence of radiation-induced ORN.

Bone Diseases↗