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Biomedical subjects

J Simon

Publications and source records attributed to J Simon.

At least 397 records · Page 22Linked to original sources
PubMed1989

The variable effects of angiotensin converting enzyme inhibition on myocardial ischaemia in chronic stable angina.

The effect of angiotensin converting enzyme inhibition on myocardial ischaemia was studied in 12 normotensive patients with chronic stable angina and exercise induced ST segment depression. The study was randomised, double blind, placebo controlled, and crossover with treatment periods of two weeks. Enalapril was used to inhibit angiotensin converting enzyme. Assessment was by angina diaries and maximum symptom limited treadmill exercise tests. The results for the whole group showed a significant reduction in systolic blood pressure at rest and at peak exercise. Mean total exercise duration was 466 s (95% confidence interval 406 to 525) when the patients were taking placebo and 509 s (436 to 583) when they were taking enalapril. Four patients prolonged their total exercise time (mean 450 to mean 591 s) by more than 20%. Two patients, however, developed ischaemia earlier on exercise and reduced their total exercise duration (mean 490 to mean 390 s). Although angiotensin converting enzyme inhibition tended to reduce myocardial ischaemia in the group as a whole, some patients improved while others deteriorated. Thus the effects of enalapril are variable and this may have important implications when enalapril is used to treat heart failure in patients with underlying severe ischaemic heart disease.

Aged↗
PubMed1989

L-leucine or its keto acid potentiate but do not initiate insulin release in chicken.

In the isolated perfused chicken pancreas, 20 and 40 mM L-leucine or 10-40 mM alpha-ketoisocaproic acid (alpha-KIC) did not initiate insulin release. In the presence of 14 mM glucose (a noninsulinotropic concentration), 20 mM L-leucine and 10 mM alpha-KIC evoked a slight biphasic insulin release. The response to 20 mM L-leucine was further increased when 14 mM glucose was combined with 10 mM L-glutamine (10 mM glutamine alone did not induce insulin release and did not potentiate the response to 10 mM L-leucine). At 1 mM, 8-bromo-adenosine 3',5'-cyclic monophosphate (8-BrcAMP) alone caused a slight and progressive increase in insulin secretion but did not sensitize the pancreas to either 20 mM L-leucine or 10 mM alpha-KIC, whereas it facilitated a marked insulin release in response to 14 mM glucose. On the other hand, 10-40 mM K+ or 20 mM L-arginine induced a rapid monophasic insulin output. In conclusion, L-leucine or alpha-KIC, which do not initiate insulin release alone and are not potentiated by 8-BrcAMP, may not be regarded as primary insulinotropic agents in the chicken. This result, together with the previously documented resistance of the chicken pancreas to glucose alone or to D-glyceraldehyde, strongly suggests that the mechanisms initiating insulin secretion are different in chickens and mammals, whereas potentiating mechanisms (low glucose concentration, arginine, acetylcholine, and cAMP) and membrane depolarization events (K+ and arginine) are present in both chickens and mammals.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1989

Extracorporeal shock wave lithotripsy for urinary stone disease: clinical experience with the electromagnetic lithotriptor 'Lithostar'.

400 urinary stone patients were treated with the electromagnetic lithotriptor Siemens 'Lithostar': 66.3% had renal stones and 33.7% had ureteral stones. Ninety percent of the treatments were performed under intravenous sedation only: 14.5% of the patients had more than one session. After 3 months more than 80% of the patients with a single stone smaller than 1.5 cm and 46% of the patients with stones larger than 2.5 cm were 'stone-free'.

Adult↗
PubMed1989

Bilateral extrapleural effusions complicating bilateral pneumonia.

In the case reported herein a patient developed bilateral pneumonia and septic shock and subsequently developed bilateral effusions. Chest roentgenograms, computed tomograms, and findings from analysis of the fluid within the chest were consistent with typical empyemas. When surgical decortication was attempted, the effusions were found to be anatomically extrapleural. Symptomatic improvement was noted following débridement.

Diaphragm↗
PubMed1989

Multiple concurrent stressors in chicks. 2. Effects on hematologic, body composition, and pathologic traits.

Effects of multiple concurrent stressors on Hubbard x Hubbard chicks (Days 10 to 17 posthatch) were studied in a 2(6)-factorial experiment employing as treatments aerial ammonia (A, 0 or 125 ppm), beak trimming (B, sham handled or beak trimmed/cauterized), coccidiosis (X, gavage with 0 or 6 x 10(5) sporulated Eimeria acervulina oocysts), intermittent electric shock (E, 0 or between 2.9 and 8.7 mA), heat stress (H, 30.4 or 34.8 C), and continuous noise (N, 80 or 95 dB). Packed-cell volume (PCV) was decreased by X and increased by A and H. A quadratic relationship between PCV and number of simultaneous stressors (order) was detected. Heterophil percentage was increased and lymphocyte percentage decreased by A, E, H, and order. Monocyte percentage was increased by N, eosinophil percentage increased by X, and basophil percentage decreased by A, X, and H. Basophil percentage decreased linearly with increasing order. Whole carcass water percentage was increased by X, chloroform-methanol extract percentage (dry matter) (CME) decreased by X, and CP percentage (dry matter) increased by A. Neither water, CME, nor CP percentage changed in relation to order. Lesion severity did not change in any tissue as stressor order increased. With few exceptions, each stressor affected hematologic, body composition, and pathologic traits in a similar manner whether imposed singly or concurrently with up to five other stressors. The results suggest that in practical production situations, where ordinarily poultry experience more than one stressor at the same time, effects of multiple concurrent unrelated stressors on performance traits can be estimated to a first approximation by summing effects of respective stressors when acting alone.

Ammonia↗
PubMed1989

[Intra- and postoperative effect of various plasma substitutes on blood rheology and conjunctival oxygen partial pressure in microsurgical intervertebral disk operations].

In a prospective, randomized, controlled, parallel group study the effect of different infusion solutions (HES 200/0.5 10%, dextran 40 10% and electrolyte solution) during and after intervertebral disc microsurgery on blood fluidity and conjunctival partial oxygen pressure was measured. At the beginning of the operation all patients showed a reduction in conjunctival oxygen pressure - independent of the infusion solution. Both fluidity of blood and oxygen partial pressure changed according to the plasma substitute used. Thus after the administration of medium molecular weight hydroxyethyl starch an improvement in the fluidity of blood with a consecutive significant increase in the conjunctival oxygen pressure could be observed, whereas there was no increase after the administration of electrolyte solution and only a slight one (according to tendency) after infusion of dextran.

Adult↗
PubMed1989

[Reliability of endorectal echography of the prostate in the screening and staging of prostatic cancer].

1433 transrectal ultrasonographies were performed for prostatic disease. In 453 cases, histopathologic correlation was obtained and compared to digital rectal examination and transrectal ultrasonography done after the clinical examination. The sensitivity of digital rectal examination was 91% and the specificity was 85%. The sensitivity and the specificity of ultrasonography were respectively 95 and 81%. 4 prostatic cancers, not suspected by digital rectal examination, were diagnosed by ultrasound (0,9%). The total number of subclinical cancer was 9 (2%). Interest of ultrasound compared to digital rectal examination concerns less than 1% of the total number of controlled patients. The staging of local extension of prostatic cancer is better by ultrasound than by the digital rectal examination. On 9 cases of clinical unsuspected extracapsular invasion, 6 were diagnosed by ultrasound.

Humans↗
PubMed1989

[Super-paramagnetic iron oxide: an MRI contrast media for the reticuloendothelial system].

In this preliminary study, the authors studies MR imaging in four patients with malignant hepatic tumours before and after intravenous injection of 20 mumols/kg of superparamagnetic iron oxide (SIO). They obtained spin-echo sequences (SE 500/28/4, SE 2 000/28, 56/2) before and after injection and systematically compared the results with ultrasonography and computed tomography data. In every case, superparamagnetic iron oxide (SIO) resulted in a marked decrease in T2 and consequently in the signal of healthy hepatic and splenic tissue, considerably improving the visualisation of malignant lesions which remained unchanged. If the detectability of lesions is considered to depend on the contrast obtained between tumours and healthy tissue, these preliminary results are very promising.

Adenocarcinoma↗
PubMed1989

Cation and guanine nucleotide effects on ligand binding properties of mu and delta opioid receptors in rat brain membranes.

Monovalent cations such as Na+, K+ and Li+ at 100 mM concentration inhibit the binding of mu and delta opioid agonists (e.g. (3H) dihydromorphine and (3H) D-Ala2-Leu5-enkephalin), enhance opioid antagonist [(3H) naloxone] binding in rat brain membranes. Divalent cations have an opposite effect: Mg2+ or Mn2+ (2mM) increase both mu and delta agonist binding, and decrease the antagonist binding. The effect of guanosine 5'-triphosphate and its non-hydrolysable analogue 5'-guanylyl-imidodiphosphate at micromolar concentrations is similar to that of sodium ion. In kinetic experiments, guanine nucleotides promote the dissociation of radiolabelled agonists from their binding sites by increasing the rate of dissociation. Equilibrium saturation binding studies show that only binding of the opioid agonist ligands are significantly inhibited by 5'-guanylyl-imidodiphosphate.

Animals↗
PubMed1989

[Relation between salt intake and blood pressure].

We investigated in a population group of 78 middle-aged men urinary sodium and potassium excretion per 24 hours under normal living conditions and the relationship to blood pressure. The mean urinary Na excretion in 24 hours was 241.3 mmol which corresponded to an intake of 14 g NaCl per day. The maximum NaCl consumption was as high as 30 g/day. The urinary Na excretion correlated in a linear fashion with the K excretion but not with the blood pressure. The blood pressure in the investigated group correlated with age, body mass index (kg/m2) and serum creatinine level. The body mass index and serum creatinine participated significantly in the blood pressure level, when multiple linear regression was used, where the urinary Na and K excretion per 24 hours were insignificant factors. In the investigated group a direct correlation of Na intake and blood pressure was not found, the investigation provided, however, information on the variability of urinary Na and K excretion/24 hours in the population and enables to estimate the necessary sample size to resolve this problem.

Adult↗
PubMed1988

[Acupuncture meridians demythified. Contribution of radiotracer methodology].

Radioactive trajectories can be visualized by injecting a radioactive tracer, technetium 99 m, at the site of acupuncture points. To determine the exact nature of these trajectories we performed several experiments on healthy volunteers, and our results may be summarized as follows. The target organs of technetium 99 m, and notably the thyroid gland, were always visualized. The circulating radioactivity, visible on scintiscans and confirmed by venous blood counts, was not negligible. The radioactive trajectories we observed were often divided at their starting point and did not extend along the whole length of the acupuncture meridians they might have made visible. The radioactive trajectories disappeared after venous blockade to reappear when the blockade was lifted. Finally, the radioactive trajectories obtained were very similar after injection at the acupuncture point and at a control point. These findings indicate a lymphatic and venous drainage of the radioactive tracer at the site of injection followed by transportation through the veins, rather than visualization of acupuncture meridians as suggested by some authors.

Acupuncture Therapy↗
PubMed1988

Insulin binding and insulin receptor tyrosine kinase activity are not altered in the liver of rats with non-insulin-dependent diabetes.

Using the insulin-glucose clamp technique, we have previously shown that an increased sensitivity to insulin in vivo is a characteristic of the liver in rats with non-insulin-dependent diabetes induced by neonatal streptozotocin administration. We have thus studied the properties of liver insulin receptor in that model. 125I-porcine insulin binding was found normal both in isolated plasma membranes and in solubilized, wheat germ agglutinin purified receptors prepared from livers of rats with non-insulin-dependent diabetes, when compared to controls. Basal and insulin-stimulated insulin receptor kinase activities were also found normal for both the autophosphorylation of the beta subunit of the insulin receptor and the phosphorylation of the artificial substrate poly (Glu-Tyr) 4:1. Thus, in that model of chronic insulin deficiency and mild hyperglycemia: 1) liver insulin receptors are not up-regulated; 2) tyrosine kinase activity remains unaffected. This last observation supports the hypothesis that the increased insulin effect in the liver of rats with non-insulin-dependent diabetes is probably distal to the insulin receptor kinase.

Animals↗
PubMed1988

Synthesis of 3H-Tyr-D-Ala-Gly-N(Me)Phe chloromethyl ketone--an opioid affinity label.

A radioactive enkephalin affinity reagent, selective for the mu opioid receptor subtype, was synthesized by a fragment condensation method. 3H-BOC-Tyr-D-Ala-Gly-OH was prepared by catalytic tritiation of the protected iodinated tripeptide. The protected tritiated tripeptide and N(Me)Phe-CH2Cl were condensed by the mixed anhydride method. The protecting group was removed by HCl/acetic acid. The tritiated tetrapeptide has a specific radioactivity of 56.8 Ci/mmole (2.1 TBq/mmole).

Affinity Labels↗
PubMed1988

Characterization of human placental opioid receptors by 3H-ethylketocyclazocine and 3H-naloxone binding.

The human placenta contains membrane bound opioid receptors. The binding of the antagonist naloxone and the fairly kappa-selective agonist EKC were studied in the microvillous membrane fraction. In both cases high affinity binding sites were detected with Kd values in the nanomolar range. A series of kappa-selective ligand (PD-117302, EKC, and U-50, 488H) were tested in displacement experiments, and found to be potent inhibitors of agonist and antagonist binding. It was confirmed that large percentage of the binding is associated with the kappa sub-type which is of current interest, in that it shows distinctive pharmacology and distribution and is selective for the natural opioid polypeptide, dynorphin.

Analgesics, Opioid↗