Vascular Disturbances Research Articles

ANALYSIS OF DISEASE MODIFYING DRUGS ADMINISTRATION FREGUENCY AND CAUSES OF THEIR WITHDRAWAL IN RHEUMATOID ARTHRITIS

Система комплексной поддержки и сопровождения научного журнала Elpub позволяет запустить двуязычный сайт журнала со встроенной системой электронной редакции в соответствии с лучшими издательскими практиками, а так же предусматривает техническую и методическую поддержку со стороны специалистов НЭИКОН.

Congenital malformations of middle and inner ears of parabiotic twins

We describe herein the congenital malformations of the middle and inner ears in temporal bones of parabiotic, monozygotic twins. Temporal bones were removed from twin B, who had no fetal cardiac activity and was born dead at 23-4/7 weeks, and twin A, the donor or "pump" twin in intrauterine life, who died shortly after birth at 20-6/7 weeks. The temporal bones were processed routinely in celoidin, stained with hematoxylin and eosin, and examined by light microscopy. We found that twin B had Mondini's dysplasia with associated deformities of the middle ear and in general showed more developmental anomalies than twin A, and we conclude that Mondini's dysplasia with anomalies of the middle ear may occur in the parabiotic twin syndrome, and the abnormalities may be explainable as the result of vascular disturbance, which also causes other lesions in these unusual cases.

Endothelial vasodilatory dysfunction in primary hyperparathyroidism is reversed after parathyroidectomy.

Primary hyperparathyroidism (HPT) is accompanied by hypertension and a cardiovascular mortality. Impaired endothelium-dependent vasodilatation (EDV) occurs in hypertension but has not been fully investigated in HPT despite the vasoactive influences of parathyroid hormone. Twenty-five HPT patients and 25 normocalcemic control subjects, matched for age and gender, underwent forearm venous occlusion plethysmography. EDV and endothelium-independent vasodilatation (EIDV) were evaluated during local infusion of metacholine (2 and 4 micrograms/min) and nitroprusside (5 and 10 micrograms/min), respectively. The endothelial function index was calculated as the ratio of forearm blood flows during the high doses of metacholine and nitroprusside. Ambulatory 24-hour blood pressures and thickness of the intima-media complex of the carotid arteries were also measured; the latter is considered an early marker of atherosclerosis. Endothelial function index was lower in the HPT patients compared with control subjects (1.01 +/- 0.26 vs 1.27 +/- 0.31, P = .003). Reinvestigation 10 months after parathyroidectomy showed normalization of the index (1.31 +/- 0.39, P = .01) due to a numeric increase in EDV and decrease in EIDV. The carotid intima-media thickness and blood pressure were similar in the groups and unaltered postoperatively. Endothelial vasodilatory dysfunction is another indicator of the vascular disturbance of HPT and can be normalized by parathyroidectomy.

Hypocalcemia in piglets reduces cardiac and pulmonary vascular disturbance after hypoxemia and reoxygenation during cardiopulmonary bypass.

Placing cyanotic newborns on cardiopulmonary bypass (CPB) and performing abrupt reoxygenation affects myocardial performance. This study tests the hypothesis that hypocalcemia is beneficial in this circumstance of reoxygenation. Twenty-one newborn piglets (anesthetized, open-chests) were placed for one hour on CPB. Seven piglets under normoxic and normocalcemic conditions were the controls. The other piglets underwent hypoxemia and subsequent reoxygenation, for periods of 30 minutes each, under normo-calcemic (Normo-Ca++, n= 7) or hypocalcemic conditions (Hypo-Ca++, n=7). Thirty minutes after discontinuation of CPB, the hemodynamic function was assessed taking into account stroke work indices (SWI), end systolic elastance (EES), pulmonary vascular resistance index (PVRI), cardiac release of conjugated dienes (CD) and creatine phosphokinase (CK), and myocardial oxygen consumption (MVO2). These parameters were expressed as a percentage of the pre-CPB value. The endogenous antioxidant reserve capacity (AORC) of ventricular wall specimens was determined by in-vitro lipid peroxidation forming malondealdehyde (nmol MDA/g protein). After one hour of CPB the cardiac performance returned to normal range without any functional or metabolic disturbance. The normocalcemic condition resulted in a hardly impaired cardiac performance (42%**SWI; 67%**EES), an augmented PVRI (more than 4-fold**), and highly elevated release of CD and CK (3-fold** each). The Normo-Ca++ group's MVO2 (95 +/- 14%) was unaltered. The hypocalcemic condition improved the myocardial function to near control value (85% SWI; 91 % EES) and attenuated the augmentation of the PVRI (n.s. vs. Control group) down to 64% of the Normo-Ca++ group's level. The release of CD and CK in the Hypo-Ca++ group (both n. s. vs. Control group) only minimally increased. The Hypo-Ca++ group's MVO2 improved (137+/-8%*). The MDA formation was worse (344+/-38**) in the Normo-Ca++ group, but unaltered in the Hypo-Ca++ group (203+/-9; n.s. vs. Control group (218+/-20)). * =p<0.05 vs. Controls and Normo-Ca++, ** =p<0.05 vs. Controls and Hypo-Ca++, using ANOVA. Hypocalcemia during hypoxemia and subsequent reoxygenation highly attenuates myocardial and pulmonary vascular disturbance in newborn piglets. This condition of low blood calcium protects cardiac function and metabolism as well as the pulmonary vascular tone due to diminished myocyte membrane damage, reduced cellular membrane lipid peroxydation, and improved endogenous antioxidant reserve capacity.

Pathological changes of the spinal cord in centenarians.

In order to study the changes that occur in the spinal cords of the aged, 19 centenarian spinal cords from two men and 17 women (age range, 100-116 years at death; mean, 103 years) were pathologically examined. Cross-sections at each segmental level of the 19 autopsied spinal cords were examined for histopathological changes. The cross-sectional area and flattening ratio at the level of the C7 segment were measured. The size of the cords had some negative correlation with age, but the individual variation was considerably large. Among the 19 centenarians, macroscopic anteroposterior flattening appeared in the lower cervical cords in six individuals. In these cases, various degrees of neuron loss were observed in the anterior horn. White matter degeneration appeared frequently, especially in the posterior column. In 12 cases, myelin loss in the fasciculus of Goll at the cervical level was observed. The degeneration of the fasciculus of Goll was considered to be upward wallerian degeneration secondary to posterior root damage at the lumbosacral level. These changes seemed to be produced by disorders in the spinal canal or surrounding tissue, such as cervical spondylosis, degeneration of the intervertebral disk and spinal canal stenosis. Argyrophilic structures such as neurofibrillary tangles and neuropil threads were observed in 16 cases; however, this incidence was less than in the brain. Medial thickening of the anterior spinal artery was found in four cords. Amyloidangiopathy was noted in only one cord. Necrosis and hemorrhage due to vascular disturbance were not found.

A four-year follow-up study on subjective symptoms and functional capacities in workers using hand-held grinders.

Fifty-three grinders in the metal industry were re-examined 4 years after their first examination. Information about age, occupation, daily vibration exposure, drinking and smoking habits, and presence of subjective symptoms such as vibration-induced white finger (VWF), and numbness and pain in the fingers was collected during the first and second examination. Cold provocation test (10 degrees C/10 min) was also employed to evaluate disturbances in the peripheral circulatory and peripheral nerves in all subjects. The frequency-weighted vibration acceleration of various types of hand-held tools was measured. There was no subject with VWF at the first examination; however, during the course of follow-up, two cases (3.8%) of VWF with latent interval of more than 25 years were diagnosed. Prevalence of numbness in the fingers and shoulder stiffness was significantly higher at the second examination. When the prevalence of subjective symptoms was tested by the subjects' total operating time (TOT) during the 4-year follow-up period, those whose TOT was equal to or more than 2500 hours showed higher prevalence compared to the other subgroup. The paired values of recovery rate of finger skin temperature and vibration sensation threshold after the cold water immersion test were significantly different at the first and second examination. On average, the diminution of hand-grip force during the 4-year follow-up course was 7.4%; the difference being significant at 0.01 level. Significant differences in the paired data of pinching power and tapping ability could be detected. The frequency-weighted vibration acceleration of various tools was in the range of 1.1-4.6 m/s2. It was concluded that: (1) prolonged occupational exposure to the vibration of hand-held grinding tools should be considered as a risk factor causing disturbances in the hand-arm system of the operators; (2) the results of recovery rate of finger skin temperature and the vibration sensation threshold seemed to be appropriate indicators for the assessment of peripheral vascular and peripheral nerve disturbances in workers exposed to hand-arm vibration; and (3) to reduce the subjects' physical stress, attention should be paid to ergonomic factors.

The human decidua as a passage-way for trophoblast invasion: A review

Summary Decidual changes in the endometrial stroma are regarded as highly important for placentation. During placental development the bulk of glandular tissue shows lateral displacement, and a progressive thinning of decidua occurs. While there is no evidence for a direct cytolytic action of trophoblast on maternal cells, local vascular disturbances may lead to superficial necrotic streaks of decidua which may subsequently regress or become incorporated into Nitabuch's layer or placental septa. Although in several rodent species decidua may act as a barrier to trophoblast invasion, which is gradually removed human where numerous trophoblastic cells invade the inner myometrium. Impairment of decidual function may be responsible for cases of placenta accreta, but cannot be invoked to explain histopathological defects in preeclampsia. In this case shallow invasion of spiral arteries is well documented, but there is no hard evidence of limited invasion of interstitial trophoblast. For proper understanding trophoblast-uterine interactions, attention of investigators should be broadened to include trophoblastmyometrial interactions.

The bradykinin B 2 receptor antagonist Icatibant (HOE 140) corrects avid Na + retention in rats with CCl 4-induced liver cirrhosis: possible role of enhanced microvascular leakage

Avid Na + retention is a hallmark of liver cirrhosis. The aim of this study was to investigate whether and how bradykinin is involved in Na + retention in rats with CCl 4-induced liver cirrhosis. To this end the bradykinin B 2 receptor antagonist Icatibant (HOE 140) was used. On one hand, bradykinin has a renal natriuretic action. On the other hand, bradykinin is a potent mediator of both vasodilation and microvascular leakage. Both vascular mechanisms, which are reported for cirrhosis, could cause vascular underfilling and Na + retention by activating the renin–angiotensin–aldosterone system. Icatibant normalised Na + retention and reduced the hyperactivity of the renin–angiotensin–aldosterone system, suggesting a bradykinin-induced vascular disturbance. Icatibant had no significant effect on the mild hypotension which developed with CCl 4 treatment. However, there was indirect evidence for enhanced microvascular leakage that was strongly inhibited by Icatibant. Our experimental results demonstrate that bradykinin is a key mediator of Na + retention in liver cirrhosis and suggest that a bradykinin-induced increase in microvascular leakage is mainly responsible.

Supersensitivity in rat micro-arteries after short-term denervation.

Contractile responses to phenylephrine and high-K+ were investigated in vitro in microvascular preparations from the rat medial plantar artery, a branch from the saphenous artery, obtained after short-term denervation in vivo. Two groups of animals were studied: (1) animals undergoing surgical resection of the saphenous nerve, and (2) animals undergoing surgical resection of both the sciatic and saphenous nerves. The animals were operated on one side only. Microvascular preparations (diameter about 325 microns) were obtained 10 days after surgery. Vessels from the non-operated side served as controls. Immunocytochemistry showed a decreased number of both neuropeptide Y (NPY) and calcitonin gene-related peptide (CGRP) immunoreactive nerve fibres in vessels after resection of the saphenous nerve only. Resection of both the saphenous and the sciatic nerve caused a complete loss of immunoreactive nerve fibres. Mechanical measurements were performed using a wire myograph. In vessels subjected to resection of the saphenous nerve the sensitivity to phenylephrine was similar to controls. Vessels denervated by resection of both the saphenous and sciatic nerves showed significant increases in phenylephrine and potassium sensitivity. When depolarized in high-K+ solution the denervated vessels showed an increased sensitivity to extracellular Ca2+. The results show that complete short-term denervation of the rat medial plantar artery in vivo causes a pronounced supersensitivity in the vascular smooth muscle. The supersensitivity appears not to be restricted to the sympathetic alpha-receptors but also associated with changes in the cellular excitation-contraction coupling. Such altered reactivity of the vascular smooth muscle may contribute to vascular disturbances observed in vivo after nerve damage or surgical denervation.

Expression of von Willebrand factor, P-selectin (CD62P) and thrombomodulin in human endothelial cells in culture modulated by cyclosporin A.

Endothelial cells were isolated from human umbilical veins and from saphenous veins and were cultured in the presence and absence of cyclosporin A (CSA). Cell morphology and growth characteristics were monitored continuously by video recording microscopy. The cells and culture supernatants were analysed for von Willebrand Factor (VWF), P-Selectin (CD62P) and thrombomodulin (TM) by immunocytochemistry and immunoassay. CSA had little effect on confluent cells in culture. In contrast, the characteristics of both umbilical vein and saphenous vein cells were markedly altered when CSA was added to subconfluent cultures. Under these conditions, CSA did not appear to be directly cytotoxic at the concentrations used but marked changes in cell morphology including the appearance of large multinucleate forms were recorded. Increased amounts of VWF and TM were detected in the culture supernatants of cells grown continuously in the presence of CSA and correspondingly depressed expression of cell associated antigens was observed. Heterogeneous and depressed distribution of CD62P was seen after 5-6 days culture but cellular expression of this ligand did not appear to be affected specifically by the presence of CSA. In addition, mechanically disrupted confluent endothelial cells failed to recover in the presence of CSA as effectively as similar cells grown in the absence of CSA. The results showed that CSA disturbed actively growing cells more severely than quiescent cells and might help to clarify the role of CSA in vascular disturbances in vivo.

Transient Osteoporosis of the Hip

Transient osteoporosis of the hip is an uncommon but probably underdiagnosed condition. There appears to be a predisposition for the condition in middle-aged males and in women in their third trimester of pregnancy. The etiology remains unclear, with theories that include vascular and neurologic disturbances. Clinical signs are usually pain in the hip area with functional disability of the affected limb. Plane film radiographs may be completely normal or show only minimal osteopenia. This report describes a 40-year-old male in whom transient osteoporosis of the hip was diagnosed. The patient's symptoms were initially interpreted as being due to sciatica; however, careful evaluation, further diagnostic work-up in the form of magnetic resonance imaging, and the clinical course of the disease ultimately led to the correct diagnosis. Resolution occurred gradually with non-steroidal anti-inflammatory drug therapy and rest. This case demonstrates the need for further evaluation of patients with hip-area pain who may have negative x-rays of the hip joint but continue to be symptomatic.

Cutaneous vasomotor responses in young Type I diabetic patients

Abnormal skin temperature reactions have been reported in type I diabetic patients. Whether this is due to a primary vascular disturbance or autonomic neuropathy is unclear. The aim of this study was to clarify this issue by evaluating cutaneous circulatory reactions before and after provocation. Seventeen type I diabetic patients and 17 age-matched controls were studied by recording blood flow (laser Doppler technique) on the dorsum of the hand (before, during, and after arterial occlusion), blood flow and skin temperatures on the dorsum of the foot and on the toe (before and after cooling followed by indirect body heating) and autonomic nerve function (heart rate reaction to deep breathing and to tilting). The results showed that before [4.6 ± 0.5 perfusion units (PU) versus 6.1 ± 0.7 PU; p = 0.0356] and after arterial occlusion (17.5 ± 1.6 PU versus 25.3 ± 1.7 PU; p = 0.0024), hand skin blood flow was significantly lower in patients than in controls. On the dorsum of the foot, skin temperature was significantly lower in patients than in controls before cooling (29.2 °C ± 0.3 °C versus 30.5 °C ± 0.4 °C; p = 0.0107) whereas toe temperature and toe blood flow were similar before and after cooling in patients and controls. After body heating, however, toe temperature (after 30 min: 25.2 °C ± 1.4 °C versus 30.9 °C ± 1.2 °C; p = 0.0022) and toe blood flow (after 30 min: 10.9 ± 2.5 °C versus 22.9 ± 4.9 PU; p = 0.0313) were significantly lower in patients than in controls, especially in patients with parasympathetic neuropathy (i.e., patients with abnormal heart rate reactions to deep breathing). In conclusion, type I diabetic patients demonstrated a vascular disturbance in their skin that seemed to be exaggerated by parasympathetic neuropathy.

Beneficial effect induced by a beta-adrenoceptor blocker on fetal growth in streptozotocin-diabetic rats.

Treatment by a beta 1-beta 2-adrenoceptor antagonist has been much used during pathological pregnancies. These agents can reduce the oxygen consumption of the myocardium, increase the coronary blood flow towards ischemic heart areas and improve return of venous blood flow towards the heart. The aim of this study was to determine the mechanism of action of this agent and to investigate whether a total beta-adrenoceptor antagonist could reduce the fetoplacental disorders elicited in streptozotocin-diabetic pregnant rats. Diabetes was engendered on day 7.5 of pregnancy, and the animals were studied on day 21. Untreated nondiabetic rats or nondiabetic rats treated with propranolol, a total beta-adrenoceptor blocker (2 mg kg-1/ day, i.p.), had a healthy placenta without vascular disturbances, with normal arterial blood velocity in the uterine artery, placenta, umbilical cord and fetal aorta, and showed eutrophic fetuses (3.9 +/- 0.0 g, mean +/- SEM). Untreated diabetic rats had severe placental lesions, with a reduction of arterial blood velocity in the uterine artery (p < 0.01), placenta (p < 0.01) and umbilical artery (p < 0.05), and exhibited fetal hypotrophy (2.3 +/- 0.1 g, mean +/- SEM, p < 0.001) compared with nondiabetic untreated rats. Treatment of diabetic rats with propranolol (2 mg kg-1/day, i.p.) enhanced fetal weight (3.66 +/- 0.2 g) and slightly increased fetal insulin secretion, restored arterial blood velocity to control values in the uterine artery and fetal aorta and reduced placental lesions. In conclusion, our results suggest that the beneficial effects of propranolol were at least in part related to an improvement of uteroplacental hemodynamics; it induced a better redistribution of the blood towards the placenta and the fetal systemic circulation. Propranolol treatment could protect cell membranes against free oxygen radicals and lipid peroxidation, involved in the pathogenesis of ischemic injury in diabetes.

Clinico-mr-tomographic characteristics of different kinds of chronic vascular multiple brain lesions

21 patient with different clinical patterns of non-insult course of developing vascular brain disturbance were included into investigation. Standard neurological examination was fol lowed by MR-tomography. Different degress of intellectualmnestic disorders and various locomotor disturbances correspond to the depicted in tomograms multiple brain lesions with cortical and subcortical foci. Comparison of clinical and MRT-data didnt reveal in full measure correlations between them.

Reflex sympathetic dystrophy: Skin blood flow, sympathetic vasoconstrictor reflexes and pain before and after surgical sympathectomy

To examine the pathophysiological mechanisms of vascular disturbances and to assess the role of the sympathetic nervous system, 12 patients with reflex sympathetic dystrophy (RSD) of the hand were studied using laser Doppler flowmetry. Cutaneous blood flow, skin resistance and skin temperature were measured at the affected and contralateral hands. Sympathetic vasoconstrictor reflexes were induced bilaterally by deep inspiration. Four patients were treated with unilateral surgical sympathectomy and pain and vascular changes were documented in follow-up investigations. (1) After acclimatization in cold environment (≤18 °C) blood flow and skin temperature were considerably lower on the affected side in 10 patients. No additional vasoconstrictor reflexes could be elicited. (2) After acclimatization in warm environment (22–24°C) blood flow and skin temperature demonstrated no side differences in all cases. Vasoconstrictor responses were the same on both sides. (3) After sympathectomy vasoconstrictor reflexes were absent. Skin resistance was considerably higher on the affected side. In the first 4 weeks the affected hand was warmer and blood flow was higher compared with the healthy side. Thereafter, skin temperature and perfusion slowly decreased and the affected hand turned from warm to cold. Very regular high amplitude vasomotion waves occurred unilaterally. There were no signs of reinnervation. Two patients had long-term pain relief. We conclude as follows. (1) Side differences in skin temperature and blood flow are no static descriptors in RSD. They are dynamic values depending critically on environmental temperature. Therefore, they have to be interpreted with care when defining reliable diagnostic criteria. (2) Vascular disturbances in RSD are not due to constant overactivity of sympathetic vasoconstrictor neurons. Changes in vascular sensitivity to cold temperature and circulating catecholamines may be responsible for vascular abnormalities. Alternatively, RSD may be associated with an abnormal (side different) reflex pattern of sympathetic vasoconstrictor neurons due to thermoregulatory and emotional stimuli generated in the central nervous system. (3) After sympathectomy, denervation supersensitivity of blood vessels and intense vasomotion may be associated with recurrence of pain in some patients.

Antibody kinetics during allopurinol treatment in canine leishmaniasis.

Morphometry of the bovine claw MORPHOMETRIC studies were carried out on claws of slaughtered cattle, including light and transmission electron microscopy of strips of the wall from coronary segment to the sole margin. Morphometry was done on the outer, middle and inner portions of the white line structures (zona alba) of unfixed horn. Horn production increased in the distal half of the wall segment, was greatest at the wall-sole border and maximal above the abaxial end of the white line, resulting in an incompletely kera- tinised and softer horn with loose intracellular connection. This area is more susceptible to vascular disturbances as the cells develop under localised pressure or in connection with laminitis. Dyskeratosis results in poor horn quality in the abaxial and axial segments of the white line, giving rise to dehiscence and an increased susceptibility to bacterial invasion. F. Vercammen, R. De Deken, Veterinary Department, Institute of Tropical Medicine, 2000 Antwerp, Belgium 264 BUDRAS, K. D., MUELLING, C. & HOROWITZ, A. (1996) American Joumal of Veterinary Research 57, 444

The Hemodynamic Abnormalities in Short-Term Insulin Deficiency: The Role of Prostaglandin Inhibition

It has been suggested that the hemodynamic derangements present in diabetic ketoacidosis are the results not only of profound volume depletion but also of the effects of increased production of vasodilating prostaglandins (PGs), principally PGI2, released by adipose tissue. In animal and in vitro models, prostaglandin synthesis is increased during insulin deficiency. We assessed the effects of short-term ketosis on the metabolic and hemodynamic variables of 10 IDDM patients free from long-term complications and of 9 normal control subjects after a 7-day randomized double-blind indomethacin (INDO) (50 mg q.i.d.) or placebo treatment period. Calf blood flow (CBF), postocclusive reactive hyperemia (PORH), and recovery half-time (an index of overall perfusion) after PORH were measured by plethysmography. Left ventricular and myocardial functions were also studied in each different condition during placebo and INDO treatment in IDDM patients. During placebo treatment, the increase in CBF during ketosis was higher (1.75 +/- 0.29 ml / min / 100 ml muscle) than during INDO (0.85 +/- 0.17 ml / min) / 100 ml muscle; P = 0.007). PORH was similar in baseline conditions, during ketosis, and in recovery in both the placebo and INDO arms. Recovery half-time significantly increased during placebo (10 +/- 2; 200%; P < 0.01) but not during INDO (1 +/- 1; 106%; NS) treatment. In normal control subjects, insulin deficiency did not induce any significant effect on hemodynamic variables. In IDDM patients, during placebo treatment, ketosis increased both the cardiac index (from 3.4 +/- 0.7 to 4.1 +/- 0.81 / min / m; P < 0.01) and the stroke index (from 42 +/- 8 to 49 +/- 7 ml/m2; P < 0.01) without changes in left ventricular ejection fraction but with a significant increase in both left and right ventricular end-diastolic volumes. Metabolic recovery induced a normalization of these parameters. INDO treatment significantly blunted these alterations. In summary, we showed that during acute insulin deficiency, INDO-sensitive mechanisms mediate vascular disturbances. Moreover, INDO treatment was capable of completely preventing the cardiac venous return and the left ventricular alterations. INDO does not interfere with the overall ketogenetic process or with insulin-induced metabolic recovery.

Rate of keratinization of the wall segment of the hoof and its relation to width and structure of the zona alba (white line) with respect to claw disease in cattle

Abstract Objectives To determine contribution of the wall segment of bovine cattle hoof to horn production, and relevance of structural differences of the wall segment and its horn production rate to claw disease. Design Epidermis and papillary body of the wall segment were examined by mesoscopy, light microscopy, and transmission and scanning electron microscopy. Morphometry of the entire length of the zona alba was examined, and the horn production rate of the wall segment was calculated. Animals Mixed-breed, dual purpose (beef and dairy) cattle of either sex, and young (20 months) Holstein-Friesian beef bulls. Procedure Blocks of a strip of the hoof from the coronary segment to the sole margin, including epidermis and dermis, were prepared for light and transmission electon microscopy. Prepared specimens of the wall-sole border were examined by scanning electron microscopy. Morphometry was performed on the outer, middle, and inner parts of the zona alba structures on unfixed horn specimens of beef bull claws. After removal of the zona alba specimens, the claw was removed and the proximodistal extent of the epidermal leaflets was measured and analyzed statistically. Results Horn production increased in the distal half of the wall segment, was greatest at the wall-sole border, and highest above the abaxial end of the zona alba. High horn production resulted in an incompletely keratinized, softer horn. Conclusions and Clinical Relevance High horn production at the zona alba increases susceptibility to vascular disturbance. Claw dyskeratoses appear first in areas of high horn production, areas which are also subject to a greater frequency of claw lesions. (Am J Vet Res 1996;57:444–455)

Remodeling of asthmatic airways by glucocorticosteroids

Airway epithelial damage and chronic inflammation are the main contributory factors in the development of asthma. Until bronchoscopic techniques were developed, clear evidence of the inflammation was relatively unknown. Today, with electron microscopy of bronchial biopsy specimens or immunohistochemistry studies, a definitive picture emerges of the cellular changes associated with the chronic inflammation of asthma, as well as evidence of the vascular disturbances that characterize this disease. 1-8 Recent studies have also shown that glucocorticoids ameliorate airways mucosal and epithelial damage by normalizing different cell types and by increasing the number of intraepithelial nerves and decreasing the number of endothelial gaps in the postcapillary venules. 9 Glucocorticoids may have an effect on the accumulation and thickening of basement membrane, thus improving intercellular communication and preventing asthma recurrences (Fig. 1). Although it is known that glucocorticoid treatment reduces the damage caused by asthma on airways mucosa and epithelium, it is difficult to envision the impact of these drugs on remodeling of asthmatic airways without current bronchoscopic techniques. This article presents an outline of airways development and the effect of glucocorticosteroids on the structural and cellular changes that occur in asthma.

A new method for measuring internal ear circulation using colored microspheres

The pathogenesis of sudden hearing loss is as yet unknown. Vascular disturbances are thought to play a major role, but they cannot be diagnosed clinically. We have therefore developed an animal model which allows measurements of the cochlear blood flow (CBF) and function. For CBF measurements a new technique based on coloured microspheres was developed. New Zealand rabbits were anaesthetised, ventilated and blood pressure and heart frequency were continuously monitored. 6 x 10(6) microspheres of one colour were injected in the left ventricle; different colours are available and allow multiple measurements. The amount of microspheres trapped in the capillary bed of the cochlea depends on the regional blood flow. An arterial reference blood sample makes it possible to calculate absolute values of the regional blood flow in the cochlea. The amount of microspheres trapped in the cochlea was determined microscopically after dissecting, dissolving and filtrating the cochlea. Measurements of the CBF in a control group (5 rabbits, 10 inner ears) at the beginning and after 120 minutes were performed. Mean CBF was 3.8 +/- 1.1 microliters/min and 4.3 +/- 1.3 microliters/min. The coloured microsphere technique allows repeated measurements of the CBF with good reproducibility and an acceptable standard deviation. CBF can be measured in absolute values, which is of advantage for determining a lower limit of the CBF for the cochlea function.