Endometrial blood perfusion as assessed using a novel laser Doppler technique in Angus cows.

Previous studies have characterized ovarian steroid synthesis which directly affects uterine environment and blood flow. Clearance of steroids occurs primarily in hepatic tissues, however, it was discovered that there is an abundant activity of the phase II steroid metabolizing enzyme UDP-glucuronosyltransferase (UGT) in uterine biopsies. No minimally invasive techniques for collecting endometrial perfusion, which is affected by steroids and indicative of reproductive health, have been developed for livestock. The objective of the present study was to characterize UGT activity and endometrial blood perfusion during a normal estrous cycle of cattle. It was hypothesized that there would be increased steroid metabolism during the luteal phase of the estrous cycle and in the uterine horn ipsilateral to the corpus luteum (CL). During the first synchronized estrous cycle, progesterone and UGT activity increased on Day 6 compared with 0 and 3, with the first day of estrus being considered Day 0 of the study. Endometrial perfusion was greater ipsilateral to the CL compared with contralateral on Day 12, and was less ipsilateral to the CL compared with contralateral on Day 18. Similar to perfusion results, nitric oxide metabolites (nitrites) were greatest in the endometrium ipsilateral as compared with contralateral to the CL. Moreover, there was a positive correlation (r = 0.28; P = .04) between endometrial perfusion and nitrite concentration. It is concluded that activity of UGT within the endometrium is affected by the contralateral or ipsilateral location of the CL, and collection of endometrial perfusion data using a laser Doppler probe could be a viable measurement technique as indicated by associated nitrite concentrations in the present study.

A simple, reliable M'Fadyean stain for visualizing the Bacillus anthracis capsule.

The simple polychrome methylene blue (PMB) staining procedure for blood or tissue smears from dead animals (M'Fadyean reaction) established in 1903 remained accepted as a highly reliable, rapid diagnostic test for anthrax for six decades while that disease was still common in livestock throughout the world. Improvements in disease control led to anthrax becoming rare in industrialized countries and less frequent in developing countries with the result that quality controlled, commercially produced PMB became hard to obtain by the 1980s. Mixed results with alternative methylene blue-based stains then led to diagnosis failures, confusion among practitioners and mistrust of this procedure as a reliable test for anthrax. We now report that, for laboratories needing a reliable M'Fadyean stain at short notice, the best approach is to have available commercially pure azure B ready to constitute into a solution of 0.03 g azure B in 3 ml of 95% ethanol or methanol to which is then added 10 ml of 0.01% KOH (0.23% final azure B concentration) and which can then be used immediately and through to the end of the tests. Stored in the dark at room temperature, the shelf life is at least 12 months. Smears should be fixed with ethanol or methanol (95-100%), not by heat, and the stain left for 5 min before washing off for optimum effect.

Acute oxalate nephropathy causing late renal transplant dysfunction due to enteric hyperoxaluria.

Calcium oxalate (CaOx) deposition in the renal allograft is an under recognized and important cause of acute tubular injury and early allograft dysfunction. We present a case of late transplant dysfunction due to acute oxalate nephropathy. The patient presented with diarrhea and deteriorating graft function, and a diagnosis of enteric hyperoxaluria secondary to pancreatic insufficiency was made. This had occurred, as the patient had been noncompliant with his pancreatic enzyme replacement therapy. Treatment to reduce his circulating oxalate load was initiated, including twice-daily hemodialysis, low fat and oxalate diet and appropriate administration of pancreatic enzyme supplements. Graft function subsequently recovered. The possibility of fat malabsorption leading to enteric hyperoxaluria should be considered in renal graft recipients presenting with loose stools and graft dysfunction.

Similarities and differences in the postjunctional role for neuropeptide Y in sympathetic vasomotor control of large vs. small arteries of rabbit renal and ear vasculature.

Neuropeptide Y (NPY) coexists and is coreleased with norepinephrine (NE) from postganglionic sympathetic nerves. A correlation between the peripheral vascular effects of NPY and the diameter of blood vessels has been proposed: NPY induces a stronger contraction in small arteries, whereas the potentiation of the contractile responses induced by other vasoconstrictors, such as NE, seems to be restricted to larger arteries where NPY exhibits little or no direct contractile activity. The purpose of the present study was to systematically characterize in vitro the contractile effects of NPY per se and the effects of NPY on contractions evoked by exogenous NE in sequential artery segments of diminishing diameter from rabbit ear and kidney. The ability of NPY to evoke vasoconstriction increased with decreasing arterial diameter. The ability of NPY to potentiate exogenous NE-induced force of contraction was restricted to larger arteries where NPY had little or no contractile effect. The velocity of NE EC50-induced force development was augmented in the presence of NPY in all ear and intrarenal arteries. This is the first report of dissociation between the potentiation of exogenous NE-induced force of contraction by NPY and the increase in velocity of NE-induced force development by NPY. If, as has been suggested by other investigators, increased rate of contraction results in potentiation of contractile responses to short trains of adrenergic nerve stimulation, this latter finding suggests that a potentiation of contractile responses to short trains of adrenergic nerve stimulation occurs at all levels of the ear and intrarenal arterial vasculature.

Functional characterization of alpha adrenoceptors on rabbit intrarenal arteries in vitro.

Vascular alpha adrenoceptors were functionally characterized in two sequential intrarenal arteries of rabbits: renal artery first order branch (IRBA) and interlobar artery (ILA). The larger diameter IRBA exhibited greater contractile sensitivity to exogenous norepinephrine (NE) and to phenylephrine than the smaller ILA. Maximum active smooth muscle cell stress to NE and phenylephrine was greater than 3 x 10(5) N/m2 for both types of vessel. The alpha-1 adrenoceptor antagonists prazosin and WB4101 shifted concentration-response curves to NE rightward, whereas the alpha-2 adrenoceptor antagonist yohimbine had no significant effect. High concentrations of clonidine and UK14304 elicited only weak contractile responses in both types of artery. Pretreatment of arteries with chloroethylclonidine significantly attenuated NE-induced contraction in the IRBA, but not in the ILA. Chloroethylclonidine and also prazosin pretreatment eliminated the difference in contractile sensitivity to NE in the two types of vessels. The combined results suggested that: 1) NE-induced vasoconstriction in rabbit intrarenal arteries (IRBA and ILA) is mediated predominantly via alpha-1 adrenoceptors; 2) a subtype (or subtypes) of alpha-1 adrenoceptor mediating vasoconstriction in the IRBA is either absent or nonfunctional in the ILA; and 3) regional differences in subtypes of alpha-1 adrenoceptor populations account for the differing functional responsiveness to NE observed in the IRBA and ILA.

Adrenergic control of intrarenal arteries of rabbits.

A comparative study of the adrenergic control of two sequential rabbit intrarenal arteries of differing diameter [intrarenal branch artery (IRBA)-unstretched lumen diameter (ULD) approximately 300 microns and interlobar artery (ILA)-ULD approximately 250 microns] has been conducted. The neurogenic contractile response of isolated segments in relation to the maximum response to l-norepinephrine (NE) was minimal (8 Hz response approximately 30% of maximum contraction) and similar in both types of arteries. Phentolamine (PTA) (10(-6) M) blocked neurally evoked contractions of the IRBAs at 2, 4, and 8 Hz and of the ILAs at 2 and 4 Hz. (8 Hz responses were not entirely blocked in 3 out of 8 ILAs.) The sensitivity to exogenous NE decreased with a decrease in intrarenal vessel diameter, whereas the maximum active smooth muscle cell stress to NE was greater than 3 X 10(5) N/m2 for each vessel. All arterial segments constricted in response to histamine (H) and NE with equal maximal effects; however, sensitivity to H was greater in the smaller artery (ILA). The comparative contractile responses to nerve stimulation and exogenous NE in sequential renal arteries contrasts to the pattern of these responses in sequential arteries in any other rabbit regional bed previously studied (pulmonary and ear vasculature).

Sources of activator calcium for extrinsic vascular tone and nimodipine inhibition of that tone in proximal vs. distal rabbit ear arteries.

The contractile responses of three artery segments of diminishing diameter in the rabbit ear (i.e., unstretched lumen diameter approximately 300 mu in central ear artery, unstretched lumen diameter approximately 150 mu in main side branch off the central ear artery and unstretched lumen diameter approximately 75 mu in terminal branch off the main side branch) to high K+, norepinephrine (NE) and 5-hydroxytryptamine (5-HT) were tested before and after their incubation in Ca++-free physiologic salt solution for times varying from 3 to 60 min. The time course of reduction of the contractile responses to K+ with Ca++-free conditions in all classes of vessels could be represented by monoexponential curves that were not significantly different from each other. The contractile response of all the ear arteries to NE and 5-HT was biphasic. The first rapid transient phase (phase I) was more resistant to change upon the removal of exogenous Ca++ than the second usually equilibrium-like component (phase II), which was dramatically and rapidly reduced (but not necessarily eliminated) by this procedure. The extent of decline upon Ca++ removal in most instances was greater for 5-HT than for NE. The rate of falloff of both phases of contraction to NE and 5-HT was faster in the smaller compared with the larger arteries. These results suggest that, as vessels in the rabbit ear arterial tree get smaller, the contribution of a tightly bound or intracellular Ca++ pool to both phases of amine-induced contraction becomes smaller, but this contribution is greater to the transient compared with the equilibrium phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Phentolamine-resistant neurogenic constriction occurs in small arteries at higher frequencies.

The effect of the alpha 1, alpha 2-antagonist phentolamine (PTA) on neuromuscular transmission and exogenous norepinephrine (NE) was assessed in arteries of diminishing diameter possessing a substantial adventitiomedial junction adrenergic innervation in the rabbit ear, i.e., central ear artery (CEA), unstretched lumen diameter (ULD) approximately equal to 300 microns; main side branch (MSB) off the CEA (ULD approximately equal to 150 microns); and terminal branch (TB) off the MSB (ULD approximately equal to 75 microns). With increasing PTA concentrations, contractile responses to transmural nerve stimulation (TNS) were decreased proportionately less in TB than in MSB and CEA. PTA (4 X 10(-6) M, a competitive antagonist concentration) blocked the tetrodotoxin-sensitive TNS-induced contractions of CEA segments at 2, 4, and 8 Hz. The response at 8 Hz was reduced at least 98% in MSB and 86% in TB. However, responses to 8 Hz were not abolished in MSB and TB until 2 X 10(-5) and 3 X 10(-5) M PTA, respectively. PTA (3 X 10(-5) M) possessed nonspecific depressant properties in addition to its alpha-antagonist properties. We conclude that the sympathetic nervous system influences tone through alpha-adrenoceptors in the CEA and in the MSB and TB at lower frequencies. Responses in the MSB and TB at higher frequencies of nerve stimulation are mediated predominately through alpha-receptors. If the possibility of a nonadrenergic transmitter is discounted, the possibilities that the small PTA-resistant component of the neurogenic response is due to a high concentration of NE acting on alpha-adrenoceptors and/or a high threshold site cannot be distinguished.

Acetylcholine induced endothelial-dependent vasodilation increases as artery diameter decreases in the rabbit ear.

Isolated resistance vessels in the rabbit ear preconstricted with histamine were relaxed by acetylcholine by a proportionately greater amount than the central ear artery. The relaxation was antagonized by atropine and also by endothelium removal. Our studies represent the first direct evidence that endothelium-dependent dilation can occur in resistance vessels.

Surgical repair of large meningomyeloceles.

Successful repair of 8 large meningomyeloceles is reported. Because these defects varied in size, shape, and location, no single procedure applied to all. Advancement flaps and both vertical and horizontal bipedicle flaps were used successfully. The latissimus dorsi and gluteus maximus muscles have been used as paired flaps. All four muscles can be mobilized simultaneously. Muscle flaps are preferable to skin flaps when feasible. The sac remnant is also available to contribute to closure when all else fails. Embryology and pathological anatomy are reviewed.

Changes in the effects of stimulation of locus coeruleus and nucleus raphe magnus following dorsal rhizotomy.

The effects of stimulating locus coeruleus (LC) and nucleus raphe magnus (NRM) on lumbar dorsal horn cells that had been denervated by dorsal rhizotomy were studied. Both LC and NRM stimulation inhibited the responses of dorsal horn cells from the side of the cord with intact dorsal roots. However, when cells from the side of the spinal cord that had had prior rhizotomies were studied, half of the units were shown to be activated by either LC or NRM stimulation.

Medial morphometry and mechanics of sequential rabbit ear arteries and myograph ring segments.

The medial structure of three different branching orders of arteries in the rabbit ear was studied to assess the possible significance with regard to mechanical behavior determined with the in vitro myograph. The central ear artery, its main side branch, and a terminal branch were fixed while dilated in situ at 100 mmHg; this resulted in internal diameters of 960, 456, and 251 micron, respectively. The average ratio of medial thickness to internal diameter was 0.0293 for arteries in situ and 0.0487 for arterial rings in vitro. Measurements undertaken for the determination of smooth muscle (SM) stress included the percentage of SM in the media (74%) and the pitch of SM (0.89 degrees). These parameters were not significantly different in the three various-sized arteries or for the two myographs. Stereological estimates of SM cell volume, length, and diameter were based on counts of SM nuclei and their length. In evaluating the ring preparation of the vessel myographs, the damage due to the wires (20%) and cut edges (6.4%) was considered. The maximum active SM stress was approximately the same in the different-sized vessels with an average value of 3.14 X 10(5) N/m2. Since this stress is comparable to measurements made by others on different mechanical apparatus and consistent for the three arterial orders, these in vitro myographs should allow for valid comparison of arterial mechanical properties over the size range studied.

Adrenergic control in three artery segments of diminishing diameter in rabbit ear.

The adrenergic neuroeffector mechanism has been assessed in three different-sized vessels of the rabbit ear, i.e., the central ear artery (CEA), which has an unstretched lumen diameter (ULD) of approximately 300 micron; a main side branch (MSB) that comes off the CEA immediately distal to the crossover position of the central vein (ULD approx 150 micron); and a terminal branch (TB) that originates from the MSB (ULD approximately 75 micron). The vessels receive adrenergic innervation limited to the adventitia as assessed by fluorescence histochemistry. Density of innervation, as indexed by neuronal uptake of tritiated norepinephrine (NE) and NE content expressed in terms of surface area of the vascular segment, appears greater in the larger vessel than in the small vessels. The neurogenic contractile response of isolated segments in relation to the maximum response to iota-NE was significantly greater in CEA than in the smaller vessels; this paralleled the neuronal density. Phentolamine (10(-6) M) blocked neurally evoked contractions of ear vessels at 2 Hz and depressed the contraction at least 90% at 4 and 8 Hz. All arterial segments constricted in response to histamine and NE with equal maximal effects. Sensitivity to NE appeared equal, whereas that to histamine appeared greater in the smaller vessels. Only the two smaller vessels possessed intrinsic tone. On the basis of the substantial innervation and neurogenic response of the vessels studied, (substantive) sympathetic control of vascular tone occurs in the three different-sized vessels of the rabbit ear, a fact that may be related to the temperature regulation role of that vascular bed.

Importance of 'cut-end' effects in in vitro artery segments.

In order to investigate the consequence of cutting a vascular segment upon its performance in vitro, the contractions of a 4-mm-long segment of ear artery to neurogenic and exogenous norepinephrine (NE) were compared to those of a similar segment cut in half. The active wall tension developed in response to exogenous NE was significantly greater in the 4-mm one-ring segment length (8.50 +/- 0.56 mN/mm) than in the two-ring 2-mm segment lengths (6.64 +/- 0.38 mN/mm) while the EC50 values were the same. The maximum tone (tension) developed at a given frequency of transmural electrical stimulation, expressed as a percentage of maximum tone developed to exogenous NE, was significantly greater (285%) in the one-ring 4-mm segment length than in the two-ring 2-mm segment lengths at the lowest frequency tested (1 Hz) while the tone was approximately equivalent at the higher frequencies (2, 4, 8 Hz). On histological examination, the internal diameter of the artery at the cut ends was less than the remainder of the segment and corresponded with a terminal zone in which the smooth muscle cells, both nuclei and cytoplasm were more deeply stained by hematoxylin and eosin. The transverse diameters of the nuclei and the cells in the end region were reduced so that the muscle cells appeared compressed. Segment 'cut-end' effects would be expected to be relatively more important in shorter ring segment lengths of vessel compared to longer segments.

Internal reflections in bleached reflection holograms.

Bleached reflection holograms produced by two plane waves in Agfa 8E56 photographic emulsion and recorded in an index-matching liquid tank at 514 nm are studied. Replay at 514 nm is both in the tank and in air, boundary reflections giving rise to multiple-output beams in the latter case. The intensities in the various output beams are measured as a function of the angle of incidence of the input beam. A simple theory based on two-wave grating diffraction and the Fresnel boundary coefficients is formulated and shown to agree with good approximation with the observed intensities of all significant output beams.

Calcium dependence of norepinephrine-induced vascular contraction in experimental diabetes.

The purpose of the study was to examine changes in the contractile responses to norepinephrine of aortas obtained from streptozotocin-induced diabetic rats and to determine the effects of changes in extracellular calcium (Ca++) concentrations on those contractile responses. Aortic rings from rats diabetic 14 to 20 days were supersensitive to norepinephrine in 0.20, 0.40 and 0.80 mM Ca++, but not in 2.50 mM Ca++. Aortas from rats diabetic 28 to 35 days showed a marked increase in contractile force to norepinephrine in 0.20, 0.40, 0.80 and 2.50 mM Ca++. The contractile force was significantly greater in the 28 to 35 day diabetic group as compared to the 14 to 20 day diabetic group. When the Ca++ concentration was changed from 2.50 mM to 0.20 and 0.40 mM, the aortas from the 28 to 35 days diabetic rats showed a significant decrease in developed tension. These data indicate that vascular reactivity is altered in experimental diabetes, and this alteration is related to the duration of the diabetic state and to the extracellular Ca++ concentration.

Influence of age on norepinephrine-induced vascular contractions as a function of extracellular calcium.

Age has been shown to produce various morphological and biochemical changes within the vasculature as well as changes in the responsiveness of the vasculature to various drugs. In the present study, the influences of age and extracellular calcium on norephinephrine-induced aortic contractions in male rats were examined. The aging process resulted in a decrease in sensitivity and responsiveness of rat aorta to norepinephrine-induced contractions. The progressive decrease in maximum contractile force (mg force/mg tissue) in response to norepinephrine as the result of aging occurred in all the different extracellular calcium concentrations used. In addition, the EC50 for norepinephrine in aortae from younger animals was directly related to the extracellular calcium concentration. As the animals, however, became progressively older (49-63 weeks) the aortic tissues became less sensitive and the calculated EC50 for norepinephrine was not altered by changes in the extracellular calcium concentration.

Excision of intramedullary arteriovenous malformation using intraoperative spinal cord monitoring.

We are presenting a patient whose intramedullary cervical arteriovenous malformation was successfully excised. The importance of monitoring somatosensory cortical evoked responses secondary to peripheral nerve stimulation is stressed.