[Telemedicine in stroke-pertinent to stroke care in Germany]

BACKGROUND AND OBJECTIVE

Telemedical stroke networks improve stroke care and provide access to time-dependent acute stroke treatment in predominantly rural regions. The aim is a presentation of data on its utility and regional distribution.

METHODS

The working group on telemedical stroke care of the German Stroke Society performed a survey study among all telestroke networks.

RESULTS

Currently, 22 telemedical stroke networks including 43 centers (per network: median 1.5, interquartile range, IQR, 1-3) as well as 225 cooperating hospitals (per network: median 9, IQR 4-17) operate in Germany and contribute to acute stroke care delivery to 48 million people. In 2018, 38,211 teleconsultations (per network: median 1340, IQR 319-2758) were performed. The thrombolysis rate was 14.1% (95% confidence interval 13.6-14.7%) and transfer for thrombectomy was initiated in 7.9% (95% confidence interval 7.5-8.4%) of ischemic stroke patients. Financial reimbursement differs regionally with compensation for telemedical stroke care in only three federal states.

CONCLUSION

Telemedical stroke care is utilized in about 1 out of 10 stroke patients in Germany. Telemedical stroke networks achieve similar rates of thrombolysis and transfer for thrombectomy compared with neurological stroke units and contribute to stroke care in rural regions. Standardization of network structures, financial assurance and uniform quality measurements may further strengthen the importance of telestroke networks in the future.

Deletion of Uncoupling Protein-2 reduces renal mitochondrial leak respiration, intrarenal hypoxia and proteinuria in a mouse model of type 1 diabetes

AIM

Uncoupling protein-2 (UCP-2) can induce mitochondrial uncoupling in the diabetic kidney. Although mitochondrial uncoupling reduces oxidative stress originating from the mitochondria and can be regarded as a protective mechanism, the increased oxygen consumption occurring secondarily to increased mitochondria uncoupling, that is leak respiration, may contribute to kidney tissue hypoxia. Using UCP-2^-/- mice, we tested the hypothesis that UCP-2-mediated leak respiration is important for the development of diabetes-induced intrarenal hypoxia and proteinuria.

METHODS

Kidney function, in vivo oxygen metabolism, urinary protein leakage and mitochondrial function were determined in wild-type and UCP-2^-/- mice during normoglycaemia and 2 weeks after diabetes induction.

RESULTS

Diabetic wild-type mice displayed mitochondrial leak respiration, pronounced intrarenal hypoxia, proteinuria and increased urinary KIM-1 excretion. However, diabetic UCP-2^-/- mice did not develop increased mitochondrial leak respiration and presented with normal intrarenal oxygen levels, urinary protein and KIM-1 excretion.

CONCLUSION

Although functioning as an antioxidant system, mitochondria uncoupling is always in co-occurrence with increased oxygen consumption, that is leak respiration; a potentially detrimental side effect as it can result in kidney tissue hypoxia; an acknowledged unifying pathway to nephropathy. Indeed, this study demonstrates a novel mechanism in which UCP-2-mediated mitochondrial leak respiration is necessary for the development of diabetes-induced intrarenal tissue hypoxia and proteinuria.

Altered response in renal blood flow and oxygen tension to contrast media in diabetic rats

Purpose: To investigate the effect of the contrast medium (CM) iopromide on renal microcirculation and oxygen tension in non-diabetic control and streptozotocin-diabetic Wistar Furth rats.

Materials and Methods: Oxygen tension was measured with Clark-type microelectrodes and blood flow with laser-Doppler flow probes. In order to differentiate between an acutely increased blood glucose concentration and a long-term diabetic state, some of the non-diabetic control rats were intravenously infused with glucose.

Results: CM decreased the medullary oxygen tension in control (non-diabetic normoglycemic) rats (∼35%) but not in diabetic rats. Medullary blood flow in control rats increased after CM administration and remained elevated, while it was unchanged in the diabetic rats. In response to CM, glucose-infused control rats responded similarly to control animals in medullary oxygen tension, but similarly to diabetic rats in medullary blood flow. Contrary to in control rats, medullary oxygen tension was unchanged in diabetic animals after CM administration.

Conclusion: Streptozotocin-diabetic rats have an altered response to intravenous injection of the CM iopromide compared to non-diabetic rats. The unaltered medullary oxygen tension, seen in the diabetic group after injection of CM, suggests that non-hemodynamic mechanisms are responsible for the increased frequency of renal failure commonly seen among diabetic patients.

ET-A receptor antagonist BQ123 prevents radiocontrast media-induced renal medullary hypoxia

Purpose: Renal vasoconstriction with resultant tissue hypoxia, especially in the renal medulla, has been suggested to play a role in contrast media (CM)-induced nephropathy. Endothelin (ET) is released into the blood stream following CM injection and has been proposed as a potential mediator through its vasoconstrictive properties.

Material and Methods: To investigate the possible protective influence of ET-receptor antagonists against CM-induced reduction in renal function, we studied the effects of injection of iopromide with and without pretreatment with BQ123 (ET-A antagonist) or BQ788 (ET-B antagonist) on renal superficial cortical flow (CBF), outer medullary blood flow (OMBF) and outer medullary oxygen tension (pO2) in normal rats.

Results: Administration of CM (1600 mg I/kg b.w.) did not affect CBF in any of the groups. However, a transient decrease in OMBF occurred, which was unaffected by both BQ123 and BQ788. Also a transient decrease in outer medullary pO2 was induced by CM administration. The pO2 reduction was significantly smaller after pretreatment with BQ123, than after injection of CM alone or together with BQ788, and pO2 returned more rapidly to the control level. Neither receptor antagonist had an effect on CM-mediated increases in electrolyte excretion.

Conclusion: In the normal rat, activation of ET-A receptors is partly involved in the depression of outer medullary pO2 caused by injection of iopromide. However, the decrease in OMBF after iopromide injection is not mediated by ET receptors. The beneficial effects of the ET-A receptor antagonist on CM-induced changes in outer medullary pO2 seem therefore not primarily mediated on the hemodynamic level but may rather involve tubular transport mechanisms.

9 ENDOSCOPY-MEDIATED INTRATUBAL INSEMINATION IN THE COW – A PRELIMINARY REPORT ABOUT THE APPLICATION OF A NOVEL MINIMALLY INVASIVE INSEMINATION TECHNIQUE

On their long path through the female reproductive tract to the fertilization site, spermatozoa are exposed to diverse influences and hazards of the cervical, uterine, and oviducal environment that naturally select viable sperms for the following fertilization. Consequently, this results in a reduction from several billions of sperms in the ejaculate to a functional sperm reservoir within the range of 102 in the isthmus of the Fallopian tube. A technique to deposit spermatozoa directly into the ampulla, thus bypassing most of the reproductive tract, enables a rigorous reduction in number of sperms deposited. Furthermore, it provides a direct assessment of sperm fertility. The aim of our study was to establish an endoscopy-assisted intratubal insemination technique using different sperm dosages, fresh or cryopreserved, to determine adequate conditions for optimal fertilization. Eighteen Simmental heifers were inseminated with fresh semen, and 9 heifers were inseminated with frozen semen using this novel technique. The heifers were synchronized using a modified Ovsynch protocol, and insemination was conducted 18 to 20 h after the second gonadotropin-releasing hormone application. Insemination of heifers was performed under epidural anaesthesia. A tubing system bearing the endoscope and an insemination device was introduced through the vaginal wall into the peritoneal cavity. The insemination device consisted of a tube connected to a curved glass capillary tube loaded with semen. After a visual examination of the ovaries for the presence of an ovulatory Graafian follicle, the capillary tube was inserted directly via the infundibulum into the ipsilateral ampulla and the semen dose was deposited. The entire procedure took ~10 min. Two days later the oviduct was flushed by the same technique. A tubing system connected to a metal catheter served for flushing the embryos and unfertilized oocytes from the oviduct into the uterine horn. Afterward, embryos and oocytes were collected by flushing the uterine horn using an embryo flushing catheter and an embryo filter (EmCon). Embryos were stained using a Hoechst dye to visualise the numbers of attached spermatozoa to the zonae pellucidae. From 18 inseminations with fresh semen doses of 7 to 28 million sperms, 7 embryos at the 2- to 8-cell stage were found. Two of these embryos had more than 10 accessory sperms (AS), 3 had 3 to 6 AS, and 2 were without AS. From 9 inseminations with frozen semen doses containing 1.5 million sperms, we obtained 2 embryos, one at the 4-cell stage without AS and one at the 8-cell stage with 5 AS. Additionally, 3 unfertilized oocytes were collected. In conclusion, these preliminary results demonstrate a promising technique for intratubal AI, which has to be further optimized by studying numbers and treatment of spermatozoa and time of insemination.

232 EFFECT OF SUPEROVULATION PRETREATMENT ON DEVELOPMENTAL CHARACTERISTICS OF IN VITRO-FERTILIZED BOVINE EMBRYOS TRANSFERRED TO THE OVIDUCT-UTERUS ENVIRONMENT

Superovulation is a routine procedure to stimulate growth and ovulation of multiple follicles. However, the hormonal changes in the reproductive tract after superovulation treatment affect the environment and subsequently the early embryo development. The aim of the study was to examine the effect of superovulation pretreatment on embryo development and gene expression of IVM/IVF derived embryos subsequently cultured in vivo. The cumulus‐oocyte complexes derived from slaughterhouse ovaries were in vitro matured and fertilized. The denuded presumptive zygotes were cultured in CR1 medium with 5% oestrous cow serum. A total of 788 cleaved embryos at Day 2 were transferred by transvaginal endoscopy into the oviduct of synchronized and superovulated heifers (superstimulated group, SS) and 784 cleaved embryos were transferred into the ipsilateral oviduct of single ovulated synchronized heifers (single ovulation group, SO). In total, 10 Simmental heifers were used for in vivo culture in a crossover design. The in vivo culture was repeated once at an interval of at least 6 weeks in the same animal. At Day 7, embryos were recovered by combined flushing of the oviducts by endoscopy and the adjacent part of the uterine horns by conventional procedure. The numbers of recovered blastocysts were recorded and the embryos were cultured for the following 48 h to determine the blastocyst rate at Days 8 and 9. Simultaneously, 410 cleaved embryos were cultured in vitro for 9 days (control group, C). Triplicate pools of 10 blastocysts recovered at Day 7 from each treatment group were used for RNA isolation. Real-time PCR using sequence specific primers was performed in StepOnePlus™ real time PCR system (Applied Biosystem, Foster City, CA, USA). A comparative threshold cycle method was used to quantify expression levels of the candidate genes compared to the internal control GAPDH gene. The number of recovered embryos after in vivo culture was significantly lower in the SS group compared with the SO group (66.9 v. 79.5%, respectively; P < 0.05). The blastocyst rates at Days 7, 8, and 9 in the SS, SO, and C groups were not significantly different (31.9, 43.3, and 47.1% v. 35.2, 48.5, and 53.5% v. 37.8, 50, and 56.1%, respectively). Molecular analysis of selected genes playing important roles during pre-implantation development revealed significantly lower expression levels of IL6, IL18, and ABCC2 between both experimental in vivo culture groups and the C-group. The IL18 was also significantly down-regulated in the SS-group compared to the SO-group. The transcription factor NFκB was found to be down-regulated in the SS-group compared to the SO and C groups (P < 0.05). In conclusion, we showed that the superovulation pretreatment did not affect blastocyst yield during the culture period but seemed to influence the expression of developmentally important genes in the resulting embryos.

Adenosine A2 a receptor stimulation prevents proteinuria in diabetic rats by promoting an anti-inflammatory phenotype without affecting oxidative stress

AIM

Diabetic patients are at increased risk for kidney disease. There is presently no clinical treatment available that effectively protects kidney function in diabetics. This study investigates whether chronic stimulation of the adenosine A2a receptor (A2a AR) protects kidney function in insulinopenic diabetic rats.

METHODS

Streptozotocin-induced diabetic rats and corresponding controls were chronically treated with the adenosine A2a AR agonist CGS21680 throughout the four-week diabetes duration. Kidney function was thereafter investigated, and urine and plasma samples were collected for analysis of protein, oxidative stress and inflammatory markers.

RESULTS

Glomerular filtration rate, renal blood flow, filtration fraction and diabetes-induced kidney hypoxia were all unaffected by chronic A2a AR stimulation. Furthermore, diabetic rats had increased oxidative stress, which was further increased by chronic A2a AR stimulation. However, the 10-fold increased urinary protein excretion observed in the diabetic rats was completely prevented by chronic A2a AR stimulation. These beneficial effects were accompanied by reduced levels of the pro-inflammatory TNF-α and increased levels of the anti-inflammatory IL-10 as well as decreased infiltration of macrophages, glomerular damage and basement membrane thickness.

CONCLUSION

Chronic A2a AR stimulation prevents proteinuria and glomerular damage in experimental diabetes via an anti-inflammatory mechanism independent of oxidative stress and kidney hypoxia.

A role for the extracellular matrix component hyaluronan in kidney dysfunction during ACE-inhibitor fetopathy

Despite data showing that inhibitors of the renin-angiotensin system increase the risks of fetal morbidity and dysfunctionality later in life, their use during pregnancy has increased. The fetopathy induced by angiotensin converting enzyme (ACE) inhibitors is characterized by anuria, hypotension and growth restriction, but can also be associated with pulmonary hypoplasia. In the kidney, this fetopathy includes atrophy of the medulla, reduced number of glomeruli, developmental lesions of tubules and vessels, tubulointerstitial inflammation and extracellular matrix accumulation. Although angiotensin II (Ang II) inhibition during nephrogenesis interferes with normal growth and development, this review will focus on effects of the heavily accumulated matrix component hyaluronan (HA). An important mechanism of HA accumulation during nephrogenesis is disruption of its normal reduction as a consequence of lack of Ang II activation of hyaluronidase. Hyaluronan has very large water-attracting properties and is pro-inflammatory when fragmented. The ensuing inflammation and interstitial oedema affect kidney function. Hyaluronan is colocalized with CD44 overexpression and infiltrating immune cells. These properties make HA a plausible contributor to the observed structural and functional kidney defects associated with the fetopathy. Available data support an involvement of HA in kidney dysfunction of the foetus and during adulthood due to the physico-chemical characteristics of HA. No clinical treatment for HA accumulation exists. Treatment with the HA-degrading enzyme hyaluronidase and an HA synthesis inhibitor has been tested successfully in experimental models in the kidney, heart and pancreas. Reduced HA accumulation to reduce interstitial oedema and inflammation may improve organ function, but this concept needs to be tested in a controlled study before causal relationships can be established.

Inhibition of sodium-linked glucose reabsorption normalizes diabetes-induced glomerular hyperfiltration in conscious adenosine A₁-receptor deficient mice

AIM

Glomerular hyperfiltration is commonly observed in diabetics early after the onset of the disease and predicts the progression of nephropathy. Sustained hyperglycaemia is also closely associated with kidney hypertrophy and increased electrolyte and glucose reabsorption in the proximal tubule. In this study, we investigated the role of the increased tubular sodium/glucose cotransport for diabetes-induced glomerular hyperfiltration. To eliminate any potential confounding effect of the tubuloglomerular feedback (TGF) mechanism, we used adenosine A₁-receptor deficient (A1AR(-/-)) mice known to lack a functional TGF mechanism and compared the results to corresponding wild-type animals (A1AR(+/+)).

METHODS

Diabetes was induced by an intravenous bolus injection of alloxan. Glomerular filtration rate (GFR) was determined in conscious mice by a single bolus injection of inulin. The sodium/glucose cotransporters were inhibited by phlorizin 30 min prior to GFR measurements.

RESULTS

Normoglycaemic animals had a similar GFR independent of genotype (A₁AR(+/+) 233 ± 11 vs. A₁AR(-/-) 241 ± 25 μL min(-1)), and induction of diabetes resulted in glomerular hyperfiltration in both groups (A₁AR(+/+) 380 ± 25 vs. A₁AR(-/-) 336 ± 35 μL min(-1); both P < 0.05). Phlorizin had no effect on GFR in normoglycaemic mice, whereas it reduced GFR in both genotypes during diabetes (A₁AR(+/+) 365 ± 18 to 295 ± 19, A₁AR(-/-) 354 ± 38 to 199 ± 15 μL min(-1); both P < 0.05). Notably, the reduction was more pronounced in the A₁AR(-/-) (P < 0.05).

CONCLUSION

This study demonstrates that increased tubular sodium/glucose reabsorption is important for diabetes-induced hyperfiltration, and that the TGF mechanism is not involved in these alterations, but rather functions to reduce any deviations from a new set-point.

Etiology of first-ever ischaemic stroke in European young adults: the 15 cities young stroke study

BACKGROUND AND PURPOSE

Risk factors for IS in young adults differ between genders and evolve with age, but data on the age- and gender-specific differences by stroke etiology are scare. These features were compared based on individual patient data from 15 European stroke centers.

METHODS

Stroke etiology was reported in detail for 3331 patients aged 15-49 years with first-ever IS according to Trial of Org in Acute Stroke Treatment (TOAST) criteria: large-artery atherosclerosis (LAA), cardioembolism (CE), small-vessel occlusion (SVO), other determined etiology, or undetermined etiology. CE was categorized into low- and high-risk sources. Other determined group was divided into dissection and other non-dissection causes. Comparisons were done using logistic regression, adjusting for age, gender, and center heterogeneity.

RESULTS

Etiology remained undetermined in 39.6%. Other determined etiology was found in 21.6%, CE in 17.3%, SVO in 12.2%, and LAA in 9.3%. Other determined etiology was more common in females and younger patients, with cervical artery dissection being the single most common etiology (12.8%). CE was more common in younger patients. Within CE, the most frequent high-risk sources were atrial fibrillation/flutter (15.1%) and cardiomyopathy (11.5%). LAA, high-risk sources of CE, and SVO were more common in males. LAA and SVO showed an increasing frequency with age. No significant etiologic distribution differences were found amongst southern, central, or northern Europe.

CONCLUSIONS

The etiology of IS in young adults has clear gender-specific patterns that change with age. A notable portion of these patients remains without an evident stroke mechanism according to TOAST criteria.

Sex-dependent insulin like growth factor-1 expression in preattachment equine embryos

An adjustment of sex ratio of offspring to the conditions present at conception is seen in many mammals including horses. This depends on preferential survival of male embryos under conditions of high energy intake. In several species, growth factors including insulin like growth factor (IGF)-1 have been shown to promote embryonic development by decreasing apoptosis and increasing cell proliferation. We hypothesized that sex-related differences in IGF-1 expression in equine embryos during the phase of maternal recognition of pregnancy might exist and thus contribute to preferential survival of embryos from either of both sexes under specific environmental conditions. Insulin like growth factor-1 mRNA expression of in vivo-produced equine embryos on different days of pregnancy (Day 8, N = 6; Day 10, N = 8; Day 12, N = 14) was analyzed. Insulin like growth factor-1 mRNA expression was evaluated by reverse transcription quantitative polymerase chain reaction. The sex of the embryo was determined by detection of X-inactivation specific transcript (Xist) RNA and equine sex determining region of the Y chromosome DNA. Embryos positive for Xist expression were classified as female, and Xist negative and equine sex determining region of the Y chromosome positive embryos were classified as male. From 28 embryos tested, 15 (54%) showed positive Xist expression and were thus classified as female. Insulin like growth factor-1 mRNA expression was influenced by sex (P = 0.01) but not by day of pregnancy (relative expression of IGF-1 in relation to β-actin, Day 8: male 5.1 ± 2.1, female 11.4; Day 10: male 5.2 ± 1.6, female 17.4 ± 6.7; Day 12: male 2.6 ± 0.3, female 11.6 ± 2.4). Results demonstrate an increased expression of IGF-1 in female equine embryos. Sex-related influences on expression of the IGF system are probably related to a gradual X chromosome inactivation.

Coenzyme Q10 prevents GDP-sensitive mitochondrial uncoupling, glomerular hyperfiltration and proteinuria in kidneys from db/db mice as a model of type 2 diabetes

AIMS/HYPOTHESIS

Increased oxygen consumption results in kidney tissue hypoxia, which is proposed to contribute to the development of diabetic nephropathy. Oxidative stress causes increased oxygen consumption in type 1 diabetic kidneys, partly mediated by uncoupling protein-2 (UCP-2)-induced mitochondrial uncoupling. The present study investigates the role of UCP-2 and oxidative stress in mitochondrial oxygen consumption and kidney function in db/db mice as a model of type 2 diabetes.

METHODS

Mitochondrial oxygen consumption, glomerular filtration rate and proteinuria were investigated in db/db mice and corresponding controls with and without coenzyme Q10 (CoQ10) treatment.

RESULTS

Untreated db/db mice displayed mitochondrial uncoupling, manifested as glutamate-stimulated oxygen consumption (2.7 ± 0.1 vs 0.2 ± 0.1 pmol O(2) s(-1) [mg protein](-1)), glomerular hyperfiltration (502 ± 26 vs 385 ± 3 μl/min), increased proteinuria (21 ± 2 vs 14 ± 1, μg/24 h), mitochondrial fragmentation (fragmentation score 2.4 ± 0.3 vs 0.7 ± 0.1) and size (1.6 ± 0.1 vs 1 ± 0.0 μm) compared with untreated controls. All alterations were prevented or reduced by CoQ10 treatment. Mitochondrial uncoupling was partly inhibited by the UCP inhibitor GDP (-1.1 ± 0.1 pmol O(2) s(-1) [mg protein](-1)). UCP-2 protein levels were similar in untreated control and db/db mice (67 ± 9 vs 67 ± 4 optical density; OD) but were reduced in CoQ10 treated groups (43 ± 2 and 38 ± 7 OD).

CONCLUSIONS/INTERPRETATION

db/db mice displayed oxidative stress-mediated activation of UCP-2, which resulted in mitochondrial uncoupling and increased oxygen consumption. CoQ10 prevented altered mitochondrial function and morphology, glomerular hyperfiltration and proteinuria in db/db mice, highlighting the role of mitochondria in the pathogenesis of diabetic nephropathy and the benefits of preventing increased oxidative stress.

Ultrasonographic evaluation of the coxofemoral joint region in young foals

The purpose of this study was to map the coxofemoral region in foals to obtain ultrasonographic reference values for the interpretation of potentially pathological findings in hip joints. Using a 7.5 MHz linear transducer, 38 examinations were carried out: 10 (20 joints) on cadavers and 28 (55 joints) on live healthy foals up to 8 weeks of age. The chosen plane of examination was caudolateral-craniomedial oblique on an imaginary line connecting the greater trochanter and the cranial edge of the tuber sacrale. The relatively thin muscular layer covering the coxofemoral joint allowed good image quality. The evaluated structures included the bone surface of the ilium and acetabulum, the subchondral bone on the femoral head and greater trochanter, the joint cartilage on the femoral head, the fibrocartilaginous acetabular labrum, the femoral capital physis, the cartilaginous layer covering the greater trochanter, the joint capsule and the presence of visible synovial fluid and the gluteal muscles. A bilateral anatomical frozen section in the plane of examination was made in one cadaver. A good correlation was found between ultrasonographic and corresponding anatomical measurements on the frozen section. This study indicated that ultrasound is a valuable diagnostic tool which can provide good image quality in neonates.

Angiotensin converting enzyme inhibition blocks interstitial hyaluronan dissipation in the neonatal rat kidney via hyaluronan synthase 2 and hyaluronidase 1

A functional renin-angiotensin system (RAS) is required for normal kidney development. Neonatal inhibition of the RAS in rats results in long-term pathological renal phenotype and causes hyaluronan (HA), which is involved in morphogenesis and inflammation, to accumulate. To elucidate the mechanisms, intrarenal HA content was followed during neonatal completion of nephrogenesis with or without angiotensin converting enzyme inhibition (ACEI) together with mRNA expression of hyaluronan synthases (HAS), hyaluronidases (Hyal), urinary hyaluronidase activity and cortical lymphatic vessels, which facilitate the drainage of HA from the tissue. In 6-8days old control rats cortical HA content was high and reduced by 93% on days 10-21, reaching adult low levels. Medullary HA content was high on days 6-8 and then reduced by 85% to 12-fold above cortical levels at day 21. In neonatally ACEI-treated rats the reduction in HA was abolished. Temporal expression of HAS2 corresponded with the reduction in HA content in the normal kidney. In ACEI-treated animals cortical HAS2 remained twice the expression of controls. Medullary Hyal1 increased in controls but decreased in ACEI-treated animals. Urine hyaluronidase activity decreased with time in control animals while in ACEI-treated animals it was initially 50% lower and did not change over time. Cells expressing the lymphatic endothelial mucoprotein podoplanin in ACEI-treated animals were increased 18-fold compared to controls suggesting compensation. In conclusion, the high renal HA content is rapidly reduced due to reduced HAS2 and increased Hyal1 mRNA expressions. Normal angiotensin II function is crucial for inducing these changes. Due to the extreme water-attracting and pro-inflammatory properties of HA, accumulation in the neonatally ACEI-treated kidneys may partly explain the pathological renal phenotype of the adult kidney, which include reduced urinary concentration ability and tubulointerstitial inflammation.

Tubular reabsorption and diabetes-induced glomerular hyperfiltration

Elevated glomerular filtration rate (GFR) is a common observation in early diabetes mellitus and closely correlates with the progression of diabetic nephropathy. Hyperfiltration has been explained to be the result of a reduced load of sodium and chloride passing macula densa, secondarily to an increased proximal reabsorption of glucose and sodium by the sodium-glucose co-transporters. This results in an inactivation of the tubuloglomerular feedback (TGF), leading to a reduced afferent arteriolar vasoconstriction and subsequently an increase in GFR. This hypothesis has recently been questioned due to the observation that adenosine A(1)-receptor knockout mice, previously shown to lack a functional TGF mechanism, still display a pronounced hyperfiltration when diabetes is induced. Leyssac demonstrated in the 1960s (Acta Physiol Scand58, 1963:236) that GFR and proximal reabsorption can work independently of each other. Furthermore, by the use of micropuncture technique a reduced hydrostatic pressure in Bowman's space or in the proximal tubule of diabetic rats has been observed. A reduced pressure in Bowman's space will increase the pressure gradient over the filtration barrier and can contribute to the development of diabetic hyperfiltration. When inhibiting proximal reabsorption with a carbonic anhydrase inhibitor, GFR decreases and proximal tubular pressure increases. Measuring intratubular pressure allows a sufficient time resolution to reveal that net filtration pressure decreases before TGF is activated which highlights the importance of intratubular pressure as a regulator of GFR. Taken together, these results imply that the reduced intratubular pressure observed in diabetes might be crucial for the development of glomerular hyperfiltration.

Lack of the serotonin transporter in mice reduces locomotor activity and leads to gender-dependent late onset obesity

OBJECTIVE

Mice deficient of the serotonin transporter (5-HTT ko) mice have a reduced brain serotonin content and develop late-onset obesity. To elucidate the pathophysiology of this obesity, we analyzed the expression of the interrelated weight-regulatory molecules: brain-derived neurotrophic factor (BDNF) and leptin receptor (LR) in brain areas associated with nutrition and activity.

RESEARCH DESIGN AND METHODS

We investigated feeding behavior, physical activity and metabolic parameters of 5-HTT ko and wild-type mice and measured the expression of BDNF and LR in brain areas associated with nutrition and activity using quantitative real-time PCR. The influence of age, gender and fasting was analyzed.

RESULTS

Male 5-HTT ko mice developed obesity without hyperphagia from the age of 5 months. Physical activity was reduced in old male, but not old female, 5-HTT ko mice. The BDNF gene expression in frontal cortex was elevated in young, but reduced in old 5-HTT ko mice. Fasting failed to increase the BDNF gene expression in frontal cortex of young 5 HTT ko mice and in the hypothalamus in old 5-HTT ko mice. The fasting-induced hypothalamic increase of LR was absent in both young and old 5-HTT ko mice.

CONCLUSIONS

We propose that low brain serotonin level due to the 5-HTT ko genotype leads to reduced physical activity and low BDNF, which together with the lack of fasting-induced hypothalamic BDNF and LR production results in late-onset obesity. Although lack of the 5-HTT is a genetic vulnerability factor for obesity, female gender is protective.

Embryo transfer induces a subclinical endometritis in recipient mares which can be prevented by treatment with non-steroid anti-inflammatory drugs

We tested the hypothesis that subclinical endometritis occurs after embryo transfer (ET) in the horse. Recipient mares were treated with meclofenamic acid (M) or flunixin meglumin (F) after ET or were left untreated (n=9 per group). Embryos were re-collected 4 days after transfer. Endometrial biopsies were taken for histology and analysis of cyclooxygenase-2 (COX-2) by immunohistochemistry and for PCR. Bacteriological swabs were collected from the uterus and lavage fluid of donor and recipient mares. Progesterone and prostaglandin F(2alpha) release was analysed in recipient mares after ET. Four days after ET, four embryos were recovered from group M and three from group F and untreated mares, each. The number of polymorph nuclear neutrophils was reduced in treated mares (p<0.05). Expression of mRNA for inflammatory cytokines did not differ between groups. In group M, expression of endometrial prostaglandin-E-synthase was higher than in group F (p<0.05). Three out of nine control mares underwent preterm luteolysis (p<0.05 vs. treatment groups), prostaglandin release (p<0.05) and the number of COX-2 positive cells (p<0.01) were significantly higher than in treated mares. Only few bacteriological swabs were positive. In conclusion, treatment of embryo recipient mares with non-steroid anti-inflammatory drugs inhibits the inflammatory response of the endometrium after ET. Meclofenamic acid may have advantages in comparison to flunixin meglumin due to a different influence on prostaglandin synthesis that may not result in inhibition of embryonic mobility.

Diabetes-induced hyperfiltration in adenosine A(1)-receptor deficient mice lacking the tubuloglomerular feedback mechanism

AIMS

Glomerular hyperfiltration is commonly found in diabetic patients early after the onset of disease. This is one of the first indications of the development of progressive diabetic nephropathy. It has been proposed that glomerular hyperfiltration is caused by decreased delivery of electrolytes to the macula densa due to the increased sodium and glucose reabsorption in the proximal tubule, which would increase the glomerular filtration rate (GFR) via the tubuloglomerular feedback (TGF) mechanism. In this study, we investigated the role of TGF in diabetes-induced glomerular hyperfiltration by inducing diabetes in adenosine A(1)-receptor knockout (A1AR(-/-)) mice known to lack a functional TGF mechanism.

METHODS

Diabetes was induced by alloxan (75 mg kg(-1) bw) injected into the tail vein. The 24-hour urinary electrolyte excretion was measured in metabolic cages, the GFR determined by inulin clearance under isoflurane-anaesthesia, and histological changes evaluated.

RESULTS

All alloxan-treated animals developed hyperglycaemia (> or =20 mm). Normoglycaemic animals had a similar GFR independent of genotype (A1AR(+/+) 9.3 +/- 0.5 vs. A1AR(-/-) 10.1 +/- 0.8 microL min(-1)g(-1) bw) and diabetes resulted in similar glomerular hyperfiltration in both groups (A1AR(+/+) 14.0 +/- 1.7, n = 9 vs. A1AR(-/-) 15.3 +/- 1.9 microL min(-1)g(-1) bw). Diabetic animals had a similar tendency to develop interstitial fibrosis, whereas the glomerular volume was similar in both genotypes, and unaltered by diabetes.

CONCLUSIONS

This study shows that the A1AR(-/-) mice develop diabetes-induced glomerular hyperfiltration, demonstrating that the TGF mechanism is not the major cause of the development of hyperfiltration. Furthermore, the hyperfiltration in the present study was not related to alterations in the glomerular filtration area.

Influence of iothalamate on renal medullary perfusion and oxygenation in the rat

PURPOSE

To evaluate controversial results regarding the effect of the contrast medium (CM) iothalamate on renal medullary blood flow by applying two different methods simultaneously.

MATERIAL AND METHODS

The outer medullary blood flow (OMBF) response was estimated using laser-Doppler flowmetry and hydrogen gas wash-out (microelectrodes) simultaneously. Outer medullary oxygen tension (PO2) was measured using Clark type microelectrodes. Iothalamate was injected i.v. at 1600 mg I/kg body weight for 2 min.

RESULTS

CM induced a transient 28% decrease in OMBF as measured with the laser Doppler. The hydrogen gas wash-out rate was reduced by 50%, indicating a reduced perfusion. CM induced a transient 60% reduction in PO2, while renal fluid and electrolyte excretion increased several fold.

CONCLUSION

The CM iothalamate reduces outer medullary perfusion as estimated by two different techniques applied simultaneously. The PO2 in the same region was also reduced. Previous controversies regarding the effect of iothalamate on OMBF can be explained by extreme dosage and injection rates greatly exceeding clinical relevance.

Polyol-pathway-dependent disturbances in renal medullary metabolism in experimental insulin-deficient diabetes mellitus in rats

AIMS/HYPOTHESIS

The renal medullary region is particularly vulnerable to reduced oxygen concentration because of its low blood perfusion and high basal oxygen consumption. This study investigated renal metabolic changes in relation to the previously observed decreased oxygen tension in streptozotocin-induced diabetic rats.

METHODS

Blood perfusion, oxygen tension and consumption, interstitial pH, and glycolytic and purine-based metabolites were determined in the renal cortex and the medulla of non-diabetic and diabetic animals by, respectively, laser Doppler flowmetry, oxygen and pH microelectrodes, and microdialysis. The importance of increased polyol pathway activity for the observed alterations was investigated by daily treatment with the aldose reductase inhibitor AL-1576 throughout the course of diabetes.

RESULTS

The diabetes-induced decrease in renal oxygen tension, due to augmented oxygen consumption, did not result in manifest hypoxia in either the cortical or the medullary region, as evaluated by microdialysis measurements of purine-based metabolites. The profound alterations in medullary oxygen metabolism were, however, associated with an increased lactate : pyruvate ratio and a concomitantly decreased pH. Notably, the renal medullary changes in oxygen tension, oxygen consumption, lactate : pyruvate ratio and pH were preventable by inhibition of aldose reductase.

CONCLUSIONS/INTERPRETATION

Substantial metabolic changes were observed in the renal medulla in diabetic animals. These disturbances seemed to be mediated by increased polyol pathway activity and could be prevented by inhibition of aldose reductase.

Quantitative analysis of MRI signal intensity as a tool for evaluating tooth pulp vitality

OBJECTIVES

To assess whether it is possible to measure tooth vitality using magnetic resonance imaging (MRI).

METHODS

Signal intensity measurements were conducted using T(1) and T(2) sequences at the region of interest in 211 teeth (35 patients).

RESULTS

Clinical findings showed that 17.3% of the teeth were avital, whereas 82.7% were found to be vital. Neither the T(2) sequence nor the non-contrast-enhanced T(1) sequence showed significant differences between vital and avital teeth. However, the contrast-enhanced sequence and, in particular, a comparison of signal intensities between the non-contrast-enhanced T(1) sequence and the contrast-enhanced sequence showed a significant difference between vital and avital teeth.

CONCLUSION

Contrast-enhanced MRI enables us to draw conclusions on pulpal perfusion in vivo.

High-resolution dental magnetic resonance imaging of inferior alveolar nerve responses to the extraction of third molars

The objective of this study was to assess whether signal changes can be detected in the neurovascular bundle of the mandibular canal after the extraction of a third molar. We retrospectively analyzed MRI scans of 30 test subjects with healthy mandibles and 41 patients who had had a wisdom tooth extracted. Signal intensities were measured at particular sites in the neurovascular bundle, which were defined as regions of interest (ROI) in the sagittal T1-weighted images before and after intravenous administration of a paramagnetic contrast agent. On the basis of the signal intensity increases that were measured after contrast agent administration, we compared the signal increases obtained for the patients who had received surgical treatment with the results obtained for the population of test subjects with unremarkable mandibles ( t-test, P<0.05). Compared with the healthy test subjects, patients who had received surgical treatment showed significantly higher signal intensity increases at two measurement sites, i.e., the second molar and the second premolar ( P<0.05). We found no significant differences when the measurements were performed at the first molar ( P=0.06), the third molar ( P=0.47) and in the area of the ascending mandibular ramus ( P=0.79). Compared with a population of healthy test subjects, patients who had their third molars surgically removed show higher signal intensity increases in the neurovascular bundle after intravenous contrast agent administration. The underlying cause may be the higher blood flow in the arteries and veins and the perineural plexus, which may give evidence of the pathophysiological mechanism of nerve damage in the narrow canal as a result of osteotomy.

MR imaging of traumatic lesions of the inferior alveolar nerve in patients with fractures of the mandible

BACKGROUND AND PURPOSE

The objective of this study was to assess whether MR imaging can image the neurovascular bundle in patients with fractures of the mandible. In addition, an attempt was made to evaluate whether MR images provide information regarding the continuity of the inferior alveolar nerve before surgery and regarding signal intensity changes after trauma.

METHODS

We analyzed preoperative MR images of 23 patients with mandibular fractures. Object-oriented sagittal view proton density- and T1-weighted sequences (before and after the administration of contrast agent) were used not only in an attempt to obtain purely qualitative information regarding nerve continuity in the neurovascular bundle (inferior alveolar nerve, artery, vein) but also to perform quantitative region-of-interest measurements of signal intensities at four defined measurement sites. The measurements were compared with those obtained for a patient population with healthy mandibles.

RESULTS

It was possible to interpret MR images in 21 cases. MR imaging findings showed that the neurovascular bundle had been cut in two patients and was intact in the remaining 19 patients. These MR imaging findings were confirmed intraoperatively in all cases. Although we found no significant signal intensity differences between patients with intact nerves and patients with cut nerves, we found significant differences between patients with mandibular fractures and patients with unremarkable mandibles.

CONCLUSION

It is possible to diagnose the interruption of nerve continuity by using MR imaging. Signal intensity measurements in the neurovascular bundle provide no information regarding nerve continuity.

Reactive oxygen species cause diabetes-induced decrease in renal oxygen tension

AIMS/HYPOTHESIS

Augmented formation of reactive oxygen species (ROS) induced by hyperglycaemia has been suggested to contribute to the development of diabetic nephropathy. This study was designed to evaluate the influence of streptozotocin (STZ)-induced diabetes mellitus, as well as the effects of preventing excessive ROS formation by alpha-tocopherol treatment, on regional renal blood flow, oxygen tension and oxygen consumption in anaesthetized Wistar Furth rats.

METHODS

Non-diabetic and STZ-diabetic rats were investigated after 4 weeks with or without dietary treatment with the radical scavenger DL-alpha-tocopherol (vitamin E, 5%). A laser-Doppler technique was used to measure regional renal blood flow, whilst oxygen tension and consumption were measured using Clark-type microelectrodes.

RESULTS

Renal oxygen tension, but not renal blood flow, was lower throughout the renal parenchyma of diabetic rats when compared to non-diabetic control rats. The decrease in oxygen tension was most pronounced in the renal medulla. Renal cellular oxygen consumption was markedly increased in diabetic rats, predominantly in the medullary region. Diabetes increased lipid peroxidation and protein carbonylation in the renal medulla. Treatment with alpha-tocopherol throughout the course of diabetes prevented diabetes-induced disturbances in oxidative stress, oxygen tension and consumption. The diabetic animals had a renal hypertrophy and a glomerular hyperfiltration, which were unaffected by alpha-tocopherol treatment.

CONCLUSIONS/INTERPRETATION

We conclude that oxidative stress occurs in kidneys of diabetic rats predominantly in the medullary region and relates to augmented oxygen consumption and impaired oxygen tension in the tissue.

High-resolution MR technique allowing visualization of the course of the inferior alveolar nerve along cystic processes

Magnetic resonance imaging is not established in the preoperative diagnosis of mandibular cystic lesions; therefore, no attempts have been made thus far to evaluate the course of the mandibular neurovascular bundle along the process. However, the radiologist can detect the neurovascular bundle along the cystic lesion by high-resolution MR imaging and convey this information to the maxillofacial surgeon. This reduces the risk of intraoperative damage of the nerve. The examination of the neurovascular bundle can easily be integrated in a tumor MRI protocol of the jaw if the slice orientation is adapted to the course of the mandibular canal.

Altered response in renal blood flow and oxygen tension to contrast media in diabetic rats

PURPOSE

To investigate the effect of the contrast medium (CM) iopromide on renal microcirculation and oxygen tension in non-diabetic control and streptozotocin-diabetic Wistar Furth rats.

MATERIALS AND METHODS

Oxygen tension was measured with Clark-type microelectrodes and blood flow with laser-Doppler flow probes. In order to differentiate between an acutely increased blood glucose concentration and a long-term diabetic state, some of the non-diabetic control rats were intravenously infused with glucose.

RESULTS

CM decreased the medullary oxygen tension in control (non-diabetic normoglycemic) rats ( approximately 35%) but not in diabetic rats. Medullary blood flow in control rats increased after CM administration and remained elevated, while it was unchanged in the diabetic rats. In response to CM, glucose-infused control rats responded similarly to control animals in medullary oxygen tension, but similarly to diabetic rats in medullary blood flow. Contrary to in control rats, medullary oxygen tension was unchanged in diabetic animals after CM administration.

CONCLUSION

Streptozotocin-diabetic rats have an altered response to intravenous injection of the CM iopromide compared to non-diabetic rats. The unaltered medullary oxygen tension, seen in the diabetic group after injection of CM, suggests that non-hemodynamic mechanisms are responsible for the increased frequency of renal failure commonly seen among diabetic patients.