Foveal retinoschisis associated with senile retinoschisis in a woman.
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Aging↗
Biomedical subjects
M W Johnson
Publications and source records attributed to M W Johnson.
Hospital risk management: the second decade.
Risk management is defined as the systematic process of identifying, evaluating and addressing potential and actual risk. Although introduced to the hospital industry nearly a decade ago, it status in Canadian hospitals remains uncertain, a position that is in sharp contrast to the American situation. Chiefly as a result of the medical malpractice crisis and associated circumstances in the mid-1970s, risk management has emerged as an integral element in the operational activities of American hospitals. The process is a mechanism for self-protection in co-operative, self-insurance arrangements and to secure commercial premium adjustments. Many trends have been recognized in canada that would suggest a predisposition toward the proliferation of risk management programs. These indicators include an increase in the number and size of claims against hospitals and physicians, a reduction in the availability of commercial health care insurance, and an increase in alternative insurance arrangements. Despite these indicators, movement toward risk management by Canadian hospitals has been minimal. A prime reason appears to be lack of financial incentives to stimulate the development of risk management programs. There is also an absence of specific accreditation standards pertaining to such programs. The case in support of risk management for Canadian hospitals continues to grow. The basic assumptions associated with a program are board, medical and staff support; a concerted effort to recognize and reduce potentially litigious situations and occurrences; and an ability to adapt. The initial steps to develop a risk management program include assessing current risk control activities and implementing structural elements. As well, a program must address its relationship to Quality Assurance activities in the hospital.
Canada↗
Hydroxychloroquine therapy in massive total doses without retinal toxicity.
To assess the relationship between hydroxychloroquine retinal toxicity and total dose, we selectively reviewed the histories of patients who had received an additive dose exceeding 1,000 g. No retinopathy was found in nine patients treated with massive total hydroxychloroquine doses ranging from 1,054 to 3,923 g. Eight of these patients were taking recommended daily doses of 400 mg/day or less and showed no evidence of toxicity. The remaining patient treated with 600 mg/day showed evidence of preretinopathy in one eye.
Adult↗
Bilateral retrobulbar optic nerve infarctions after blood loss and hypotension. A clinicopathologic case study.
A 59-year-old woman with anemia became totally blind after repeated gastrointestinal bleeding and acute hypotension. Neuropathologic examination was normal apart from bilateral infarctions centered on the orbital portion of the optic nerves. This is the only "pure" histopathologic study of visual loss after hemorrhage and hypotension in the recent literature, the single previous case being complicated by arteriosclerosis and vasculitis. The authors suggest that visual loss after hypotension is of three types. Profound hypotension in patients with neither anemia nor arteriosclerosis generally causes water-shed infarctions in the parietal and occipital lobes. Brief hypotension combined with arteriosclerosis favors juxtalaminar optic nerve infarction indistinguishable from spontaneous anterior ischemic optic neuropathy. In anemic patients without arteriosclerotic risk factors, hypotension is likely to cause infarction in the orbital optic nerve, where pial end vessels are subject to compression from hypoxic edema.
Blindness↗
Design considerations in development of a prototype, piezoelectric internal fixation plate: a preliminary report.
The piezoelectric internal fixation plate represents a new concept in orthopaedic implants. The purpose of this device is to provide stable bone fixation while delivering internally generated, microampere direct currents to prevent or treat nonunion of a fracture or osteotomy. Clinically, currents of this type have been effective in treatment of nonunion, but application has required separate, implanted, or external battery or radiofrequency powered circuits. The "piezoplate" being developed contains an integral piezoelectric element that generates current in response to either physiological loading such as weightbearing or to externally applied ultrasound. Currents are processed by a rectifying circuit for delivery to bone by electrodes. Specially designed series/parallel piezoelectric elements and dual processing circuits are required to generate optimum rectified currents from the low-frequency, high-voltage signals generated by weightbearing, as well as the high-frequency, low-voltage signals produced by ultrasound. This paper reports on the current status of development and describes design parameters of this device which combines the modalities of mechanical fixation and electrical stimulation in a single implant.
Animals↗
The impact of a drug information sheet on the understanding and attitude of patients about drugs.
A proposed Food and Drug Administration program to require written information with prescription drugs could cost $500 million annually; the American Medical Association has implemented a similar, voluntary program costing more than $3 million. However, the educational impact of written drug information has not been studied. We evaluated one-page drug information sheets using an objective examination. The baseline score of 71 patients was 3.9 of 6.0. Patients tested before and one day after receiving the drug sheet improved their score by +1.4. In the second phase, patients randomized to receive the drug sheet improved their score after one month by +1.1; those not given the sheet had no improvement. Changes in attitudes and incidence of reported adverse effects seemed to be random and unrelated to the information sheet. Thus, a drug information sheet may be a useful adjunct to patient education.
Attitude↗
Piezoelectric internal fixation devices: a new approach to electrical augmentation of osteogenesis.
Prototype testing has been accomplished on a piezoelectric, internal fixation plate. This device combines a piezoelectric material with an internal fixation device as an integrated structure that provides mechanical stability, together with self-generated electrical stimulation, for treating fractures and nonunion. In bench and animal tests we have demonstrated that cyclical loading can cause a device of this type to generate electrical charge while attached to bone. After rectification, direct currents within the range known to stimulate osteogenesis can be produced by weight-bearing loads. Furthermore, electrical output of the implants can be increased by externally applied ultrasonic energy. These twin developments add significantly to the potential armamentarium of devices to enhance bone healing.
Animals↗
Behavior of fluid in stressed bone and cellular stimulation.
The behavior of the fluid in stressed bone is examined in order to determine what stimuli cells in bone would experience when bone is stressed. It is found that the fluid pressure in the vascular channels should have a very short relaxation time, on the order of milliseconds in vivo. The case for the lacunar-canalicular systems is more difficult to analyze, but the fluid pressure in these pore systems may not relax as rapidly. The experimental evidence concerning fluid flow is difficult to interpret because of the complicated porosity in bone and the dependence of the permeability on sample preparation techniques. Nevertheless, the data are consistent with a fast relaxation time for the vascular channels in vitro, which means that the long relaxation time observed in the electromechanical effect is due either to the flow in the lacunar-canalicular systems or to the flow in the microporosity.
Animals↗
The relationship between base composition and codon usage in bacterial genes and its use for the simple and reliable identification of protein-coding sequences.
Bacterial genes that code for proteins appear to possess a codon usage characteristic of their overall base composition. This results in different but predictable non-random distributions of nucleotides within codons, permitting the recognition of protein-coding sequences in a wide range of bacterial species. The nature of this distribution depends on the base composition of the coding sequence. The position-specific differences are especially conspicuous in genes of extreme G + C content, allowing the particularly reliable prediction of the reading frame and coding strand of experimentally determined DNA sequences. This finding has been exploited to identify the coding sequence of the viomycin phosphotransferase (vph) gene of Streptomyces vinaceus. An easily applied computer program ("Frame") has been written to carry out and display such analyses.
Bacterial Proteins↗
Accessory muscle activity during sleep in chronic obstructive pulmonary disease.
Hypoventilation contributes to oxyhemoglobin desaturation during rapid-eye-movement (REM) sleep in patients with severe chronic obstructive pulmonary disease (COPD). Due to hyperinflated lungs these patients have mechanically impaired diaphragms and increased activity of other inspiratory muscles while awake. We speculated that rib cage (RC) inspiratory muscles might lose activity during REM, thereby contributing to hypoventilation. We therefore recorded scalene (SCA) and sternocleidomastoid (SCM) electromyorgrams in six subjects with severe COPD. SCA activity decreased 76% (P less than 0.001), from non-REM (NREM) to tonic REM and decreased an additional 17% during phasic REM. SCM activity was much more variable during NREM but when present also decreased during REM. SCA activity correlated strongly with RC excursion. SCA and SCM activity, RC excursion, estimates of minute ventilation, and oxyhemoglobin saturation all decreased in parallel. Expiratory activity of the SCA and SCM, present during wakefulness and NREM, disappeared during REM. We conclude that loss of inspiratory activity of rib cage muscles during REM causes chest wall distortion and hypoventilation in patients with severe COPD. Loss of expiratory activity of these muscles may contribute to a decrease in end-expiratory volume and thereby to a deterioration of pulmonary gas exchange.
Diaphragm↗
Induction of the obstructive sleep apnea syndrome in a woman by exogenous androgen administration.
We documented airway occlusion during sleep and an abnormally high supraglottic resistance while awake in a 54-yr-old woman who had developed physical changes and the syndrome of obstructive sleep apnea while being administered exogenous androgens. When the androgens were withdrawn, the patient's physical changes, symptoms, sleep study, and supraglottic resistance all returned to normal. A rechallenge with androgen produced symptoms of obstructive sleep apnea that abated upon withdrawal of the hormone. Previous reports have favored a role of androgens in the pathogenesis of sleep apnea. Our report provides direct evidence for this role. Structural and functional measurements indicate that androgens exert a permissive or necessary action on the structural configuration of the oropharynx that predisposes to obstruction during sleep. Development of the obstructive sleep apnea syndrome must be considered a possible side effect of androgen therapy.
Anabolic Agents↗
The impact of an educational program on gentamicin use in a teaching hospital.
We evaluated the effectiveness of a structured educational program in improving the gentamicin prescribing pattern of physicians in the hospital. Predetermined criteria for acceptable use were based upon the specific indications for initiating the drug therapy, the dosage regimen, and the precautions taken to avoid toxicity. In the preeducation review period, 57 of 109 courses of gentamicin (52 percent) were found acceptable. Following the educational program, 93 of 120 courses (78 percent; p less than 0.001) were acceptable; indications for gentamicin use that were found unacceptable decreased from 11 percent to 5 percent (p less than 0.005) and the incidence of excessive doses declined from 21 to 7 percent (p less than 0.005). We conclude that a structured educational program may improve the prescribing pattern of physicians.
Adolescent↗
Fluid flow in bone in vitro.
Recent dielectric measurements suggest that the electromechanical effect in wet (fluid saturated) bone is not due to a piezoelectric effect. This would imply that the electromechanical effect observed in wet bone is due to a streaming potential and is therefore dependent on fluid flow in stressed bone. A model for fluid flow in bone in vitro is presented. This model predicts a rapid decay (of the order of a millisecond or less) for the fluid flow in Haversian systems. The implications of this result for the interpretation of the electromechanical effect in wet bone are discussed.
Biomechanical Phenomena↗
Follicular carcinoma of the thyroid metastatic to the kidney 37 years after resection of the primary tumor.
A case is described of thyroid carcinoma presenting as renal metastases 37 years after initial resection of the primary. Thyroid carcinoma metastatic to the kidney detected during life is rare, only 2 cases having been reported to date. An additional feature of this case is that the patient had donated the contralateral kidney for transplantation before discovery of the metastases. Metastatic thyroid carcinoma is reviewed and the implication of organ donation in patients with thyroid carcinoma is discussed.
Adenocarcinoma↗
Relationship between sex hormones, myocardial infarction, and occlusive coronary disease.
An alteration in sex hormones has been considered a risk factor for myocardial infarction. In this study, estradiol (E2) and testosterone (T) levels were evaluated in healthy firefighters, patients with myocardial infarction acutely and during their convalescence, patients with no evidence of occlusive coronary artery disease on arteriography, and patients with chronic angina pectoris in whom there was at least one vessel that indicated 50% occlusive coronary artery disease. Although T levels were similar in all groups, E2 levels were substantially higher in patients with myocardial infarction and in patients with chronic angina pectoris. These results support the hypothesis that elevated estrogen levels may be a risk factor for myocardial infarction and coronary artery disease, possibly by promoting clotting or coronary spasm.
Adult↗
Infection control as the focus for a new course for medical students.
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Cross Infection↗
Unique needs of women pharmacy residents.
The needs of women residents in hospital pharmacy programs are discussed with respect to the responsibilities of preceptors to help residents prepare for a successful career. Women were a small minority within the profession of pharmacy until recently. More than half of the current hospital pharmacy residents are women, while over 95% of the preceptors of residency training programs are men. Hospital pharmacy preceptors can help meet the unique needs of women residents, so that women pharmacists can achieve the career successes of which they are capable. Preceptors can help women residents make career decisions and develop career goals and strategies. Preceptors should ensure that women residents develop the broad base of knowledge and skills necessary for advancement. Women residents should be encouraged to get involved in pharmacy organizations, and the importance of networking should be stressed. It is important that women residents develop a business style so that they are perceived as confident and competent. Preceptors must recognize that most women will have conflicts in their roles of career woman, wife, and mother. Preceptors can also help women residents by making managerial changes (e.g., offering part-time positions and flexible scheduling) that will facilitate integration of the professional and personal responsibilities of women.
Day Care, Medical↗
Pressor effect of naloxone in septic shock.
Naloxone was given intravenously to thirteen patients with prolonged hypotension. Eight patients with sepsis who were not receiving corticosteroids had a 45% increase in systolic blood-pressure within minutes of receiving 0.4--1.2 mg of naloxone. The increase in blood-pressure lasted for at least 45 min. In two patients a second dose, given after recurrence of hypotension, resulted in another increase in blood-pressure. Four patients with hypoadrenocorticotropism had no pressor response to naloxone. These observations suggest that endorphins may contribute to the hypotension of sepsis and that naloxone may have therapeutic value in the treatment of septic shock.
Adrenal Insufficiency↗