shukoor65/lab-rag-model huggingface dataset:
Acid secretion and suppression. Hydrochloric acid is involved in the causation of peptic ulcer, but the exact role has not been defined. Suppression of acid secretion is associated with ulcer healing. The acid secreting cell is the parietal cell, which possesses a proton pump in the secretory membrane; morphologic changes accompany and facilitate the active secretion of hydrochloric acid. Stimulation of acid secretion occurs by three major pathways, which utilize acetylcholine, histamine, and gastrin. The predominant effects of histamine are mediated by adenylate cyclase, whereas those of gastrin and acetylcholine involve cytosolic calcium. There is a complicated arrangement of receptors and pathways that culminate in the activation of the proton pump. The parietal cell is influenced by neurocrine, hormonal, and paracrine mechanisms. Peptides join the more familiar neurotransmitters in affecting the parietal cell. Somatostatin is present in the gut and acts to decrease acid secretion. The hormone gastrin is released, in a feedback fashion, when the antrum is alkalinized. Most stimuli of acid secretion are blocked by H2-antagonists. Inhibitory hormones are released when acid arrives in the intestine. Inhibition of acid secretion can be achieved by influencing the parietal cell at the level of histamine, gastrin, and muscarinic receptors. The proton pump itself can be blocked by drugs that inhibit the final phase of acid secretion.
Platelet emboli in rat brain cross when the contralateral carotid artery is occluded. The pathogenesis of embolic events ipsilateral to an occluded carotid artery is uncertain. To examine this question we combined occlusion of the left common carotid artery with embolism from the right common carotid artery in rats. Following ligation of the left carotid artery in 20 experimental rats, we irradiated the right carotid artery with a laser (632 nm, 200 mW/cm2, 12-15 minutes) following the intravenous injection of 12.5 mg/kg of the photosensitizing agent Photofrin II. Controls had left carotid artery occlusion with (n = 13) or without (n = 6) Photofrin II. Fifteen of the 20 experimental rats survived to be perfused at 24 hours; cerebral infarcts were identified in 12 rats, with bilateral infarcts in 10. There were 112 infarcts (101 small [less than 2.5 mm] and 11 large [greater than 2.5 mm] on the right and 103 (93 small and 10 large) on the left. Emboli were seen in association with some infarcts and were evenly distributed in the two hemispheres (37 emboli on the right and 40 on the left, with the midline azygous artery occluded in four animals). Left carotid artery occlusion did not produce infarcts or emboli in the controls. We conclude that cerebral infarcts in the distribution of an occluded common carotid artery may be caused by emboli from the contralateral carotid artery in rats.
Traditional first-line therapy. Overview of medical benefits and side effects. When diuretic-based stepped care was first advocated for the treatment of hypertension, there were fewer classes of antihypertensive medication than there are today. In 1984, the third Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC) for the first time suggested an alternative initial treatment with a beta-blocker in selected hypertensive patients, and the fourth JNC report has recommended the alternatives of calcium channel blockers or angiotensin converting enzyme inhibitors for step-one therapy as well. However, only the diuretic drugs and beta-blockers have been shown to reduce cardiovascular morbidity and mortality in prospective, long-term, controlled trials. Moreover, 30 years' experience with diuretic agents and 20 years' experience with beta-blockers have defined the advantages, disadvantages, and potential side effects of these drugs more precisely than is possible for newer agents. The diuretic drugs and beta-blockers remain excellent choices in the management of hypertension.
Timing of invasive procedures in therapy for primary and secondary spontaneous pneumothorax. Timing of invasive procedures during chest tube therapy in spontaneous pneumothorax is undefined. Evaluation of 115 patients with primary and secondary spontaneous pneumothorax treated with tube thoracostomy revealed nearly maximal healing rates after 48 hours without a relevant increase if drainage was maintained for up to 10 days. In secondary spontaneous pneumothorax, a significantly lower healing rate was observed after 48 hours compared with primary spontaneous pneumothorax (60% vs 82%). Therapeutic success was not predictable by single clinical variables available at admission (eg, age, gender, and smoking habits) nor by their combinations. Recurrence rates were 30% in both primary and secondary spontaneous pneumothorax. Hospital stay averaged 6 days in primary and 15 days in secondary spontaneous pneumothorax. Considering their efficacy and the low incidence of complications, the early use of invasive procedures such as surgical pleurectomy, after 48 hours of persistent gas leaking, seems justified. Shorter in-patient care and lower recurrence rates may result.
Focal high signal on MR scans of the midbrain caused by enlarged perivascular spaces: MR-pathologic correlation. Punctate and linear foci of abnormal signal were observed near the substantia nigra in the midbrains of 32 (20%) of 157 patients undergoing high-resolution MR imaging of the brainstem. The lesions were most easily seen on long TR/long TE images, where they were of high signal intensity. Their location was consistently in the lower mesencephalon near the junction of the substantia nigra and cerebral peduncle. Unilateral lesions were observed in 18 cases, while bilateral lesions were noted in 14. A review of anatomic specimens revealed the constant presence of penetrating branches of the collicular or accessory collicular arteries in this location. Enlarged perivascular spaces around these vessels were frequently seen in the specimens and probably account for punctate and linear foci observed on high-resolution MR images of the midbrain.
Dietary calcium supplementation as a treatment for mild hypertension. The blood pressure responses of 19 mildly hypertensive (diastolic blood pressure 90-104 mmHg) individuals to treatment with either 1200 mg of elemental calcium supplementation or placebo were assessed weekly in a 6-month randomized, double-blind, placebo-controlled crossover study. Both groups showed a decrease in blood pressure (calcium treated: 6 +/- 12 mmHg systolic, 7 +/- 7 mmHg diastolic; and placebo controlled: 9 +/- 14 mmHg systolic, 9 +/- 8 mmHg diastolic). Differences between the two groups were not significant (P greater than 0.1). There were no adverse effects to either treatment. This study does not support the hypothesis that dietary calcium supplementation is more effective than placebo in reducing blood pressure in mildly hypertensive individuals.
cis-platinum ototoxicity in children. Cis-platinum is an ototoxic antineoplastic drug. Evaluation of auditory thresholds in 33 children receiving cis-platinum shows that a threshold shift at 6 and 8 kHz is first measurable after a cumulative dose of 201 to 300 mg/m2. A 35- to 40-dB high-frequency threshold shift is evident after a cumulative cis-platinum dose of 301 to 400 mg/m2. Increasing cumulative doses of cis-platinum are associated with a greater degree of hearing loss. Receiver-operator characteristic curves were used to find a criterion value that effectively identified threshold shifts that were due to cis-platinum ototoxicity. A 15-dB or greater shift in the 6- and 8-kHz threshold average identifies a high true-positive (50%) and low false-positive (0%) rate of cis-platinum-induced hearing loss. Using this criterion, cis-platinum ototoxicity affected 77% of children who received cis-platinum (median cumulative dose 360 mg/m2).
Ultrastructural localization of interferon-producing cells in the livers of patients with chronic hepatitis B. Cells expressing alpha- and gamma-interferon were localized in the liver tissue of patients with chronic hepatitis B by means of light and electron microscopy using monoclonal antibodies. Interferon-positive cells were regularly seen in the infiltrating mononuclear cells, and the number showed a good correlation with the degree of the necroinflammatory activity of the disease. In chronic persistent hepatitis and in normal livers, they were infrequent or virtually absent. alpha-Interferon was shown to be positive in lymphocytes, polymorphonuclear leukocytes and fibroblasts, Kupffer cells and, weakly, in the cytoplasm of a few hepatocytes in cases of active hepatitis, whereas gamma-interferon was demonstrated only in lymphocytes. The expression of human leukocyte class I antigens on hepatocytes showed a close association with the number of interferon-producing cells, but not with the presence of virus particles and HBcAg in liver cells, when studied using electron microscopy and double-labeling. Interferon seems to be an important regulator of the local immune response in the liver in patients with chronic hepatitis B. Its functions may play a role in inducing the human leukocyte class I antigen expression on hepatocytes, thus enhancing the elimination of virus-containing hepatocytes by major histocompatibility complex-restricted cytotoxic lymphocytes.
Factors affecting perioperative pulmonary function in acute respiratory failure. To determine the magnitude, duration, and associated factors of perioperative changes in pulmonary function, we retrospectively reviewed the medical records of 145 patients who required preoperative mechanical ventilation for acute respiratory failure before undergoing 200 surgical procedures. Patients were grouped into five pulmonary diagnostic categories: (1) adult respiratory distress syndrome (ARDS) (n = 49); (2) pneumonia (n = 20); (3) atelectasis (n = 65); (4) congestive heart failure (n = 11); and (5) acute ventilatory failure (n = 55). Sixty patients underwent intra-abdominal surgery, 135 patients required surgery on the periphery, and five patients had a thoracotomy. For all patients, PaO2/FIO2 declined significantly from 321 mm Hg (mean) preoperatively to 258 mm Hg intraoperatively, and shunt fraction (Qs/QT) increased from 0.16 to 0.23 without a significant change in PaCO2. The magnitude of the increase in Qs/QT did not differ among pulmonary diagnostic groups. Preoperatively, patients undergoing laparotomy had lower PaO2/FIO2 (278 vs 340) and higher Qs/QT (0.19 vs 0.14) than patients requiring surgery on the periphery. Intraoperatively, Qs/QT increased more during abdominal procedures than during peripheral procedures. Intraoperative hypoxemia (PaO2/FIO2 less than 80 mm Hg) occurred during 13 procedures. Hypoxemic patients had a mean increase in Qs/QT of 0.20 (0.25 preoperatively to 0.45 intraoperatively), and a significant increase in PaCO2 from 38 mm Hg to 45 mm Hg intraoperatively). In general, these patients had ARDS (n = 10), sepsis (n = 10), a laparotomy (n = 9), and intraoperative mechanical ventilation via the Ohio Anesthesia ventilator (n = 8), a commonly used operating room ventilator. Their preoperative peak airway pressure (54 cm H2O) and minute ventilation (20 L/min) requirements exceeded the capabilities of the Ohio Anesthesia ventilator and likely contributed to impaired gas exchange intraoperatively. Within the first several hours postoperatively, PaO2/FIO2 recovered to preoperative levels in all patients, even in those who had severe intraoperative hypoxemia develop and who underwent laparotomy. We conclude that most patients with acute respiratory failure receiving preoperative mechanical ventilation experienced mild-to-moderate deterioration in intraoperative pulmonary oxygen exchange that rapidly returned to preoperative levels after surgery. We recommend that necessary surgery not be postponed by concern that pulmonary function will be worsened by surgery and anesthesia.
Cough, exertional, and other miscellaneous headaches. We have discussed several miscellaneous headache disorders not associated with structural brain disease. The first group included those headaches provoked by "exertional" triggers in various forms. These include benign cough headache, BEH, and headache associated with sexual activity. The IHS diagnostic criteria were discussed. Benign exertional headache and cough headache were discussed together because of their substantial similarities. In general, BEH is characterized by severe, short-lived pain after coughing, sneezing, lifting a burden, sexual activity, or other similar brief effort. Structural disease of the brain or skull was the most important differential diagnosis for these disorders, with posterior fossa mass lesions being identified as the most common organic etiology. Magnetic resonance imaging with special attention to the posterior fossa and foramen magnum is the preferred method for evaluating these patients. Indomethacin is the treatment of choice. The headache associated with sexual activity is dull in the early phases of sexual excitement and becomes intense at orgasm. This headache is unpredictable in occurrence. Like BEH, the headache associated with sexual activity can be a manifestation of structural disease. Subarachnoid hemorrhage must be excluded, by CT scanning and CSF examination, in patients with the sexual headache. Benign headache associated with sexual activity has been successfully treated with indomethacin and beta-blockers. The second miscellaneous group of headache disorders includes those provoked by eating something cold or food additives, and by environmental stimuli. Idiopathic stabbing headache does not have a known trigger and appears frequently in migraineurs. Its occurrence may also herald the termination of an attack of cluster headache. Indomethacin treatment provides significant relief. Three headaches triggered by substances that are eaten were reviewed: ingestion of a cold stimulus, nitrate/nitrite-induced headache, and MSG-induced headache. For the most part, avoidance of these stimuli can prevent the associated headache. Lastly, we reviewed headache provoked by high altitude and hypoxia. The headache is part of the syndrome of AMS during its early or benign stage and the later malignant stage of HACE. The pain can be exacerbated by exercise. The best treatment is prevention via slow ascent and avoidance of respiratory depressants. Acetazolamide and dexamethasone have proved useful in preventing this syndrome.
Differentiation therapy of acute promyelocytic leukemia with tretinoin (all-trans-retinoic acid). BACKGROUND AND METHODS. Patients with acute promyelocytic leukemia have a characteristic (15;17) translocation, with a breakpoint on chromosome 17 in the region of the retinoic acid receptor-alpha (RAR-alpha). Since this receptor has been shown to be involved with growth and differentiation of myeloid cells in vitro, and since recent clinical studies have reported that tretinoin (all-trans-retinoic acid) induces complete remission in patients with acute promyelocytic leukemia we studied the effects of tretinoin on cellular maturation and molecular abnormalities in patients undergoing the induction of remission with this agent. RESULTS. Eleven patients with acute promyelocytic leukemia were treated with tretinoin administered orally at a dose of 45 mg per square meter of body-surface area per day. Nine of the 11 patients entered complete remission. In two patients, complete remission was preceded by striking leukocytosis that then resolved despite continued drug treatment. Serial studies of cellular morphologic features, cell-surface immunophenotypic analysis, and fluorescence in situ hybridization with a chromosome 17 probe revealed that clinical response was associated with maturation of the leukemic clone. All patients who responded to treatment who were tested by Northern blot analysis had expression of aberrant RAR-alpha. As patients entered complete remission, the expression of the abnormal RAR-alpha message decreased markedly; however, it was still detectable in several patients after complete morphologic and cytogenetic remission had been achieved. CONCLUSIONS. Tretinoin is a safe and highly effective agent for inducing complete remission in patients with acute promyelocytic leukemia. Clinical response to this agent is associated with leukemic-cell differentiation and is linked to the expression of an aberrant RAR-alpha nuclear receptor. Molecular detection of the aberrant receptor may serve as a useful marker for residual leukemia in patients with this disease.
Canine myocardial creatine kinase isoenzymes after chronic coronary artery occlusion. BACKGROUND. Creatine kinase (CK) exists as three cytosolic isoenzymes, CK-MM, CK-MB, and CK-BB, and one mitochondrial isoenzyme. Animal and human observations suggest that the CK-MB content of myocardium is dynamic and may increase in response to ischemia, but the response of the myocardial CK system to chronic coronary artery occlusion is not well-defined. METHODS AND RESULTS. We measured serial changes in myocardial total CK, percent CK-MB, and percent CK-BB before and 3 weeks after coronary artery occlusion in 17 pentobarbital-anesthetized dogs. Tissue biopsies were obtained from the left anterior descending (LAD) coronary artery myocardium, the right coronary artery (RCA) myocardium, and the circumflex coronary artery myocardium at baseline and 3 weeks after LAD occlusion (n = 6), RCA occlusion (n = 5), and no coronary artery occlusion (n = 6). Tissue samples were assayed for total CK, percent CK-MB, and percent CK-BB. Samples were also examined by electron microscopy for evidence of ischemic myopathy. Total myocardial CK activity did not change over 3 weeks. Percent CK-MB increased significantly in the tissue supplied by the occluded artery (4.1-fold in dogs with LAD occlusion and 6.7-fold in dogs with RCA occlusion). Percent CK-BB did not change. Dogs with LAD occlusion had ultrastructural evidence of myopathic fibers interspersed with normal fibers in the LAD myocardium. Dogs with RCA occlusion had no ultrastructural evidence of myopathic fibers in the RCA myocardium. CONCLUSIONS. Chronic coronary artery occlusion causes a pronounced change in the canine myocardial CK system that is limited to the tissue supplied by the occluded coronary artery. These biochemical alterations do not correlate with any cellular ultrastructural changes. Myocardial CK-MB content is dynamic, varies geographically within the heart, and increases rapidly after coronary artery occlusion.
Segmental neurofibromatosis. Two patients had localized multiple cutaneous neurofibromas; one had bilateral involvement of the scalp and the other had true segmental neurofibromatosis. Other signs of neurofibromatosis were absent. Segmental neurofibromatosis may not be related to the generalized types of neurofibromatosis but may be a cutaneous hamartoma.
Mandible reconstruction with vascularized bone grafts. A histologic evaluation. To our knowledge, a histologic evaluation of bone healing after mandible reconstruction with vascularized human bone grafts has not been previously reported. Serial sections through both the decalcified graft and the junction between mandible and graft were evaluated in four patients who required surgical removal of their reconstructed mandibles. A failed scapular bone graft that had been wrapped within a pectoralis major myocutaneous flap for salvage following pedicle thrombosis showed markedly resorbed but viable bone with a fibrous union to the native mandible. Viable vascularized grafts without evidence of ongoing resorption characterized an iliac osteocutaneous bone graft and two scapula osteocutaneous grafts that healed with continuity of healthy bone between graft and mandible. Observations from the evaluation of these specimens are made regarding bone circulation, bone union, and bone graft survival as they occur clinically. Implications regarding the techniques of bone plating and indications for use of vascularized bone in mandible reconstruction are discussed.
Conservative treatment and long term prophylactic thyroxine in the prevention of recurrence of multinodular goiter. It has not been universally agreed upon that there is an optimum treatment for multinodular goiter and that use of thyroxine postoperatively in preventing recurrence is effective. We have studied a group of 185 patients who underwent thyroid gland operations and who were observed for a mean period of 10.25 years. Of these, 171 patients received postoperative thyroxine in a dose of 100 micrograms per day and a small group (14 patients) received no medication. In the group receiving no thyroxine, there were six recurrences, and in the group that received postoperative prophylactic thyroxine, there were nine recurrences, which is statistically significant (p = 0.003 per cent). When recurrences did occur in the thyroxine treated group they were small and easily managed by increasing the dose of thyroxine. No patient who took thyroxine postoperatively continuously underwent a second thyroidectomy. We conclude that, in this series, our policy of resecting only macroscopically pathologic thyroid tissue and prescribing prophylactic postoperative thyroxine is successful in preventing recurrent nodular goiter.
Immunohistochemical quantification of substance P in spinal dorsal horns of patients with multiple system atrophy. Using a computer-assisted image analyser, an immunohistochemical quantification method of substance P-like immunoreactivity (SPLI) in laminae I + II of spinal dorsal horn was established and applied to 13 patients with multiple system atrophy (MSA) with no disturbance of pain sensation, including olivo-ponto-cerebellar atrophy and striatonigral degeneration, and 13 neurologically normal controls. To investigate whether alteration of SPLI is related to an autonomic disorder, myelinated fibre counts of the fourth thoracic ventral roots were performed. Eleven of 13 MSA patients showed a significant decrease in small and large myelinated fibres, and were diagnosed with definite Shy-Drager syndrome (SDS), with the exception of two who had no apparent history of autonomic dysfunction. SPLIs in laminae I + II in 10 of these 11 patients, when adjusted for age, were significantly decreased at both levels of the fourth thoracic and third lumbar spinal segments. The results suggest the disorder of SP-containing synapses of primary afferent neurons and/or those of interneurons in SDS.