Proopiomelanocortin but not vasopressin or renin-angiotensin system induces resuscitative effects of central 5-HT1A activation in haemorrhagic shock in rats.

The aim of this study was to determine the effectory mechanisms: vasopressin, renin-angiotensin system and proopiomelanocortin-derived peptides (POMC), partaking in the effects of serotonin through central serotonin 1A receptor (5-HT1A) receptors in haemorrhagic shock in rats. The study was conducted on male Wistar rats. All experimental procedures were carried out under full anaesthesia. The principal experiment included a 2 hour observation period in haemorrhagic shock. Drugs used - a selective 5-HT1A agonist 8-OH-DPAT (5 µg/5 µl); V1a receptor antagonist [ß-mercapto-ß, ß-cyclo-pentamethylenepropionyl(1),O-me-Tyr(2),Arg(8)]AVP (10 µg/kg); angiotensin type I receptor antagonist (AT1) ZD7155 (0.5 mg/kg, i.v.); angiotensin-converting-enzyme inhibitor captopril (30 mg/kg, i.v.); melanocortin type 4 (MC4) receptor antagonist HS014 (5 µg, i.c.v.). There was no influence of ZD715, captopril or blocking of the V1a receptors on changes in the heart rate (HR), mean arterial pressure (MAP), peripheral blood flow or resistance caused by the central stimulation of 5-HT1A receptors (P≥0.05). However, selective blocking of central MC4 receptors caused a slight, but significant decrease in HR and MAP (P<0.05). POMC derivatives acting via the central MC4 receptor participate in the resuscitative effects of 8-OH-DPAT. The angiotensin and vasopressin systems do not participate in these actions.

Influence of joint position on electromyographic and torque generation during maximal voluntary isometric contractions of the hamstrings and gluteus maximus muscles.

STUDY DESIGN: Repeated measures analysis of joint angle effects on hip and knee muscle electromyographic (EMG) activity. OBJECTIVES: To simultaneously determine angle-dependent changes in maximal voluntary isometric contraction (MVIC) torque and EMG activity during hip extension and knee flexion. BACKGROUND: Procedures for normalizing EMG data and for determining torque-angle relationships for various joint motions both entail asking subjects to exert an MVIC. The implicit assumption in these paradigms is that magnitude of the EMG response is at a constant, maximum level so that observed angle-dependent variations in torque are due to mechanical factors, such as muscle length and muscle moment arm. METHODS AND MEASURES: Fifty subjects (25 men and 25 women) participated in this study (age, 23.5 +/- 4.6 y; range, 18-38 y). Subjects performed maximal isometric knee flexion at 4 knee angles and maximal isometric hip extension at 4 hip angles. The dependent variables were normalized root-mean-square EMG and torque. The process for normalizing EMG and torque data consisted of determining the largest mean value for each subject across testing positions for the muscle of interest. That value was designated as corresponding to 100% MVIC, and all other data for that muscle were expressed as a percentage of the MVIC value. Repeated measures was used to determine angle-dependent changes in normalized MVIC-torque and MVIC-EMG values for each muscle group. RESULTS: Mean torque-angle relationships were generally consistent with previous reports, though considerable intersubject variability was observed. There were significant angle-dependent differences in maximal EMG for both the hamstring and gluteus maximus muscles. Mean percentages of hamstring MVIC-EMG at knee angles of 30 degrees (81 +/- 19) and 60 degrees (82 +/- 22) were greater than at 0 degrees (68 +/- 20) or 90 degrees (74 +/- 20). The mean percentage of gluteus maximus MVIC-EMG at a hip angle of 0 degrees (94 +/- 10) was greater than at 30 degrees (84 +/- 13), 60 degrees (80 +/- 14), or 90 degrees (64 +/- 20), and gluteus maximus maximal voluntary isometric EMG at 90 degrees was less than at all other angles. These differences could not be explained solely by muscle length-dependent effects on EMG amplitude, suggesting that despite instructions for maximal effort, motor unit activation was not maintained at a constant, maximal level throughout the range of motion. The form of the EMG/angle relationships differed markedly from the torque-angle relationships. CONCLUSIONS: These findings have implications for the use of MVIC-EMG for reference values in EMG normalization procedures and for the interpretation of mechanisms underlying the torque-angle relationships observed in vivo.

Visual phenomena, disturbances, and hallucinations.

The visual system and its processing of sensory information can be affected in a variety of ways that may be either normal or associated with numerous disorders and diseases. Visual images produced by the intrinsic components of the eyes are often normal and are known as entoptic phenomena. In contrast, the visual system may be disrupted by various disorders and pathologic processes, which can result in metamorphopsia, transient loss of vision, and positive scotomas. Such disruptions can be secondary to retinal and optic nerve disease, migraines associated with visual auras, and cerebrovascular and neurologic diseases; they can also be side effects of certain drugs. In addition, the visual system may process incoming sensory information in such a way that what is seen is perceived incorrectly, i.e. illusion; or the visual system may produce images of things not really there, i.e. hallucination. Various types of visual phenomena, disturbances, and hallucinations are discussed. The numerous visual presentations need to be differentiated so that appropriate treatment, management, and patient education can be rendered.

How common are renal angiomyolipomas in patients with pulmonary lymphangiomyomatosis?

Pulmonary lymphangiomyomatosis has been associated with renal angiomyolipoma in case reports, but the prevalence of this association has not been well documented. The objective of this study was to determine the frequency of renal angiomyolipoma in a series of subjects with pulmonary lymphangiomyomatosis. Eighteen consecutive patients with pulmonary lymphangiomyomatosis were seen at a single institution between 1989 and 1994. Of these, one patient was excluded because she did not have an abdominal computed tomographic (CT) scan. We found eight out of 17 (47%) patients with pulmonary lymphangiomyomatosis to have renal angiomyolipomas. These were found either at surgery or on abdominal CT scanning. Thus, renal angiomyolipomas occur commonly in association with pulmonary lymphangiomyomatosis. Consequently, the early detection of renal angiomyolipoma by abdominal CT may be important, because lesions with dimensions larger than 4 cm may present an increased risk for complications related to tumor growth or hemorrhage. Serial follow-up by ultrasonography or CT scanning is important in identifying and monitoring high-risk patients. Prophylactic treatment (partial or total nephrectomy) may be considered for patients with tumors that show significant growth or other complications, such as hemorrhage.

Detection of a novel sequence change in the major form of alpha-MSH isolated from the intermediate pituitary of the reptile, Anolis carolinensis.

Intermediate pituitaries of the reptile, Anolis carolinensis, were separately pulse labeled with [3H]Trp and [3H]Tyr. The major form of alpha-MSH was purified by immunoprecipitation and isolated by reverse phase HPLC. Tryptic peptide analysis indicated that the [3H]Trp-labeled C-terminal fragment of Anolis alpha-MSH had the same retention time as mammalian ACTH(9-13) amide; however, the [3H]Tyr-labeled N-terminal fragment did not coelute with either mammalian ACTH(1-8) or N-acetyl-ACTH(1-8). Purification of alpha-MSH from 76 Anolis intermediate pituitaries confirmed that a sequence change had occurred in the N-terminal region of Anolis alpha-MSH. The tissues were acid extracted and purified by Sephadex G-25 chromatography and reverse phase HPLC to yield 4.5 micrograms of purified Anolis alpha-MSH for amino acid composition analysis and automated Edman degradation sequence analysis. The major form of Anolis alpha-MSH is nonacetylated and has the following novel primary sequence: Ser-Tyr-Ala-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro(Val-amide). The presence of Val-amide was verified by immunological analysis, tryptic peptide analysis and amino acid composition analysis.

Analysis of ACTH-related and CLIP-related peptides partially purified from the pituitary of the Australian lungfish, Neoceratodus forsteri.

Acid extracts of individual lungfish pituitaries were fractionated by gel filtration on a Sephadex G-75 column and aliquots of column fractions were screened with a heterologous ACTH(1-39) radioimmunoassay (RIA). Two major, incompletely separated, peaks of ACTH-related immunoreactivity were detected. These peaks of ACTH-related material were resolved by reverse-phase high-performance liquid chromatography and were designated Peak A and Peak B. Peak A had a retention time more hydrophilic than synthetic human CLIP [ACTH(18-39)], whereas Peak B had a retention time similar to, but not identical with, human ACTH(1-39). Further analysis indicated that Peak A had an apparent molecular weight of 2.5K and an isoelectric point of 4.3. Based on these characteristics, Peak A would appear to be lungfish CLIP. Peak B had an apparent molecular weight of 4.5K. Based on chromatographic and immunological properties, Peak B would appear to be lungfish ACTH. The detection of these lungfish peptides by heterologous RIA indicates a high degree of primary sequence homology between lungfish and tetrapod ACTH-related polypeptides.

Retinal arterial macroaneurysm: a longitudinal case study.

Retinal arterial macroaneurysms are a relatively rare clinical entity that occur most frequently in the elder female population. They are strongly associated with systemic hypertension. Variable clinical presentations may occur, which may often lead to misdiagnosis. Correct diagnosis is essential for proper follow-up care and potential treatment. Differential diagnosis includes Coats' disease, angiomatosis retinae, Leber's miliary aneurysm, diabetic retinopathy, ectopic neovascular membrane, and malignant melanoma. The importance of the differential diagnosis is exemplified in a case report of a macroaneurysm which, upon initial ophthalmoscopic presentation, was concealed by surrounding retinal hemorrhage. The clinical features, differential diagnosis, management, and treatment of retinal macroaneurysms are discussed.

Anterior ischemic optic neuropathy in Buerger's disease.

A 77-year-old man with a history of Buerger's disease developed an anterior ischemic optic neuropathy. This disease, while rare in the United States at the present time, is common in other parts of the world. None the less, this appears to be the first reported case of this type of optic neuropathy in a patient with documented Buerger's disease. A possible mechanism is suggested.

Oculopharyngeal muscular dystrophy.

Oculopharyngeal muscular dystrophy (OPMD) is a rare progressive disease characterized by bilateral ptosis and dysphagia. A case report of a patient of French-Canadian descent is presented. The importance of OPMD is emphasized, not only in its differential of ptosis, but also because of the possible sequella from the dysphagia of weight loss, pulmonary infection, choking and tracheal aspiration.

Purification, characterization, substrate and inhibitor specificity of adenosine kinase from several Eimeria species.

Ribonucleosides of some pyrazolo [3,4-d] pyrimidines have been shown to be potent anticoccidial agents. To investigate their interactions with adenosine kinase, this enzyme was purified by affinity chromatography from the sporulated oocysts of 3 avian coccidia, Eimeria tenella, E. acervulina and E. brunetti as well as from chicken liver. Comparative studies revealed several differences among the enzymes. Magnesium appeared not to be inhibitor of the E. tenella enzyme but did inhibit the enzymes from the other three sources. ATP in excess of the magnesium concentration strongly inhibited the E. brunetti enzyme but had only a small effect on the other enzymes. The chicken liver enzyme utilized a broader variety of triphosphate donors than did any of the enzymes from Eimeria species. ATP, dATP, GTP, dGTP and ITP was the best substrates. Studies with pyrazolo [3,4-d] pyrimidine nucleosides revealed two groups of enzymes with similar inhibitor specificities, the chicken liver and E. Acervulina vs. the E. tenella and E. brunetti enzyme. This grouping roughly correlates with the in vivo anticoccidial specificity of these compounds. Substrate specificity studies using two 4-substituted pyrazolo [3,4-d] pyrimidine ribonucleosides (ethylthio- and cinnamylthio-), which have shown potent anticoccidial activity in vivo, revealed that each served as a substrate for the enzymes from E. tenella and E. acervulina. The E. tenella enzyme was the more efficient at the phosphorylation of those compounds. However, only the ethylthio- compound was detectably phosphorylated by the enzyme from E. brunetti. In contrast to the inhibitor specificity, the substrate activities of these nucleosides do not correlate well with their in vivo anticoccidial activity.