Time interval between the onset of symptoms and diagnosis of multiple sclerosis and the influential factors: A national registry-based study

OBJECTIVE

The time to diagnosis of multiple sclerosis (MS) is of great importance for early treatment, thereby reducing the disability and burden of the disease. The purpose of this study was to determine the time from the onset of clinical symptoms to the diagnosis of MS and to evaluate the factors associated with a late diagnosis in Iranian MS patients.

METHODS

The present cross-sectional study was conducted on patients with MS who were registered in the National MS Registry System of Iran (NMSRI).

RESULTS

Overall, 23291 MS patients registered in 18 provinces of Iran were included in this study. The mean (standard deviation) interval between the onset of the disease and diagnosis of MS was 13.42 (32.40) months, and the median was one month. The diagnostic interval of 41.6% of patients was less than one month, and 14.8% of them had a one-month time to diagnosis. Patients with an age of onset below 18 years and those diagnosed after the age of 50 years had a longer time to diagnosis (P<0.001). Patients with primary progressive MS (PPMS) had the longest time to diagnose and those with relapsing-remitting MS (RRMS) had the shortest time (P<0.001). The results of negative binominal regression showed that the average rate of delay in diagnosis in women was 12% less than that in men. The average delay in diagnosis in patients with a positive family history of MS was 23% more than that in others. The rate of delay in the diagnosis of patients with PPMS and secondary progressive MS was 2.22 and 1.66 times higher, respectively, compared with RRMS.

CONCLUSION

The findings of the present study revealed that more than half of the MS patients were diagnosed within a one-month interval from the symptom onset, which is an acceptable period. More attention should be paid to patients' access to medical facilities and MS specialists.

Economic and Social Standing of Individuals in Iran Diagnosed with Multiple Sclerosis

BACKGROUND

Multiple sclerosis (MS) may be affected by socioeconomic status (SES). This study aims to explore the determinants of SES among Iranian patients with MS and examine how these factors relate to disability and disease progression.

METHODS

All patients with MS listed in the nationwide MS registry of Iran (NMSRI) until January 8, 2022, were included in this population-based study.

RESULTS

Among the 5153 patients, most were female (74.5%), married (70.8%), and did not hold an academic degree (53.8%). Unemployment (OR: 3.75) and being unmarried (OR: 2.60) were significantly associated with Expanded Disability Status Scale (EDSS)≥6, and the time to progression was shorter in the unemployed group (P value: 0.03). There was also a significant negative correlation between the time to progression and the age at disease onset.

CONCLUSION

The study suggests that providing financial and social support to MS patients and their families through investment could reduce both individual and societal burdens.

Epidemiological parameters of multiple sclerosis in Chaharmahal and Bakhtiari Province, Iran

Background: Multiple sclerosis (MS) is a neurological disease with a high burden and disability. There are reports of various medications' side effects on patients with MS. The aim of the study is to determine the characteristics and medicine usage distribution among patients with MS in Chaharmahal and Bakhtiari Province in Iran. Methods: This registry-based cross-sectional study was performed among MS cases in Chaharmahal and Bakhtiari Province. The epidemiological data were collected from the nationwide MS registry of Iran (NMSRI) from 2019 to 2022. The information collected included age, sex, family history, type of MS, age at MS onset and diagnosis, MS symptoms, physical condition, and history of medication use. All tests were performed at a significance level of 0.05 using SPSS software. Results: A total of 416 patients included in this study. Among them, 325 individuals (78%) were women with mean ± standard deviation (SD) of age of 37.35 ± 8.51 years. No significant difference was observed between men and women in terms of age, type of MS disease, family history of MS, and physical condition (P > 0.05). The results showed that the Expanded Disability Status Scale (EDSS) score in female patients (1.41) was different from the EDSS score in male patients (1.77) (P < 0.05). Most of the patients often used interferon beta (IFN-β). Conclusion: The results provided new insight into the epidemiology and medicine patterns of patients with MS in Chaharmahal and Bakhtiari Province. The epidemiological situation of MS in this province is similar to other parts of Iran. Planning according to national programs is suggested for the management and control of MS.

Late-onset multiple sclerosis in Iran: A report on demographic and disease characteristics

BACKGROUND

Today, it is estimated that around 5% of multiple sclerosis (MS) patients are in the late-onset category (age at disease onset ≥ 50). Diagnosis and treatment in this group could be challenging. Here, we report the latest update on the characteristics of Iranian patients with late-onset MS (LOMS).

METHODS

This cross-sectional study used the information provided by the nationwide MS registry of Iran (NMSRI). The registrars from 14 provinces entered data of patients with a confirmed diagnosis of MS by neurologists. Patients with disease onset at or later than 50 years of age were considered LOMS.

RESULTS

Of 20,036 records, the late-onset category included 321 patients (1.6%). The age-standardized LOMS prevalence was around 75 per 100,000 people. 215 patients (67%) were female. Median Expanded Disability Status Scale (EDSS) was 3 (interquartile range: 1.5-5). The majority of the cases (56%) suffered from relapsing-remitting (RR) course while 20% were diagnosed with primary progressive (PP) MS. Significantly higher proportion of male sex, PPMS, and higher EDSS were seen in the late-onset group compared with early-onset and adult-onset cases (p-value < 0.05). Seventy-five (23%) patients did not receive any disease-modifying treatment.

DISCUSSION

The more prominent degenerative pathology of LOMS may be the underlying mechanism of the observed differences in comparison to non-LOMS.

CONCLUSION

There are substantial differences and knowledge gaps regarding LOMS which could be the subject of further research.

Epidemiology of familial multiple sclerosis in Iran: a national registry-based study

Background

Admittedly, little is known about the epidemiological signatures of familial multiple sclerosis (FMS) in different geographical regions of Iran.

Objective

To determine the epidemiology and the risk of FMS incidence in several provinces of Iran with a different ethnic population including, Fars, Tehran, Isfahan (Persians), and Mazandaran (Mazanis), Kermanshah (Kurds), and Chaharmahal and Bakhtiari (Lors).

Methods

This cross-sectional registry-based study was performed on nationwide MS registry of Iran (NMSRI) data collected from 2018 to 2021. This system, registers baseline characteristics, clinical presentations and symptoms, diagnostic and treatments at regional and national levels.

Results

A total of 9200 patients including, 7003 (76.1%) female and 2197 (23.9%) male, were participated. About 19% of patients reported a family history of MS; the order from highest to lowest FMS prevalence was as follows: Fars (26.5%), Chaharmahal and Bakhtiari (21.1%), Tehran (20.5%), Isfahan (20.3%), Mazandaran (18.0%), and Kermanshah (12.5%). Of all FMS cases, 74.7% (1308 cases) were female and 25.3% (442 cases) were male. FMS occurrence was much more common in females than males (P-value = 0.001). Further, the mean age at onset was 30 years among FMS cases. A substantially higher probability of relapsing-remitting MS and secondary-progressive MS was found among FMS cases than sporadic MS (SMS) (P_value = 0.001). There was no significant difference in Expanded Disability Status Scale (EDSS) scores between FMS and SMS. The majority of FMS cases were observed among first-degree relatives, with the highest rate in siblings. There was a significant association between MS risk and positive familial history in both maternal and paternal aunt/uncle (P_value = 0.043 and P_value = 0.019, respectively). Multiple sclerosis occurrence among offspring of females was higher than males (P_value = 0.027).

Conclusions

In summary, our findings imply a noteworthy upward trend of FMS in Iran, even more than the global prevalence, which suggests a unique Atlas of FMS prevalence in this multi-ethnic population. Despite the highest rate of FMS within Persian and Lor ethnicities, no statistically significant difference was observed among the provinces.

WITHDRAWN: Incidence and mortality of COVID-19 in Iranian multiple sclerosis patients treated with disease-modifying therapies

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Comparison of Lumbopelvic and Hip Movement Patterns During Passive Hip External Rotation in Two Groups of Low Back Pain Patients with and without Rotational Demand Activities

BACKGROUND

Because different groups of people with low back pain (LBP) engage in different tasks, their lumbopelvic-hip complex may move in different ways in those groups. The purpose of this study was to quantify the differences in lumbopelvic movement pattern during the passive hip external rotation (PHER) test in LBP patients with and without rotational demand activities (RDA).

MATERIAL AND METHODS

A total of 30 subjects with LBP, including 15 patients with-RDA and 15 patients without-RDA were enrolled. A passive hip external rotation test was performed. Pelvic and hip rotation over the full range of the test, timing of hip and pelvic motion, and pelvic rotation in the first half of the movement were measured using a 3-D motion analysis system.

RESULTS

Passive pelvic rotation during the test in the group with RDA was significantly greater than in the other group. However, there was no significant difference between the groups in other kinematic variables, including hip external rotation, timing of hip and pelvic motion and pelvic rotation in the first half of the movement (p > 0.05).

CONCLUSIONS

1. A greater lumbopelvic rotation ROM during the PHER existed in LBP patients who regularly participated in RDA. 2. Different groups of patients with LBP who engage in different specific activities may have a specific lumbopelvic movement pattern impairment. Therefore, each group of LBP patients in regard to their specific activities may need a different, specific plan of treatment.

Gastrointestinal-specific anxiety: an important factor for severity of GI symptoms and quality of life in IBS

BACKGROUND

Gastrointestinal (GI)-specific anxiety (GSA) has been proposed to influence symptom severity and quality of life (QOL) in patients with irritable bowel syndrome (IBS). The Visceral Sensitivity Index (VSI) is a recently developed, reliable and valid measure of GSA. Our aim was to evaluate the association between GSA, GI symptom severity, and QOL in IBS patients.

METHODS

Sixty healthy subjects and 306 patients fulfilling the Rome II criteria for IBS were studied. Demographic and disease-related factors were assessed. Patients completed VSI and GI Symptom Rating Scale (GSRS) and questionnaires to determine psychological symptom severity (Hospital Anxiety and Depression Scale), QOL (Short form 36), and presence of functional GI disorders (Rome II Modular Questionnaire).

KEY RESULTS

Compared with healthy subjects, patients with IBS had more severe GSA (34.7 +/- 16.9 vs. 2.2 +/- 4.4 [mean +/- standard deviation]; P < 0.0001). In the IBS group, more severe GSA was seen in patients with more severe GI symptoms (P < 0.0001), general anxiety (P < 0.0001) and depression (P < 0.0001), and with lower socioeconomic status (P < 0.05). In a regression analysis, GSA was the strongest predictor for GI symptom severity (GSRS total score), followed by number of Rome II diagnoses, presence of meal-related IBS symptoms, and gender (R(2) = 0.34). Gastrointestinal-specific anxiety was also, together with general anxiety, depression, socioeconomic status, and gender, found to be independently associated with mental QOL (R(2) = 0.62).

CONCLUSIONS & INFERENCES

Gastrointestinal-specific anxiety seems to be an important factor for GI symptom severity and QOL in patients with IBS.

Depression prevalence and related factors in Iranian students

This study designed to determine prevalence and related factors of depression in student of Arak, Iran. An analytical cross-sectional study was conducted on 304 undergraduate medical and basic students in Arak Universities, Markazi Province, Iran from May 2008 to July 2008. GHQ-28 questionnaire has been used for data gathering and analyzed by t and Chi square tests. Mean of mental health in students was 26.18 +/- 11.02 and 52.3% of students scored above the threshold of the GHQ- 28, indicating psychiatric disorder. Female sex, uninteresting of major, an uncertain future and positive family history were the most important risk factors of depression. In results didn't observe any significant relationship between age, education major and year. The prevalence of depression was higher than as compared to all population and in female exceed to male students. But there wasn't any difference between medical and non medical students. So attention to financial and occupational future graduated and under graduated students is essential.

Heightened central affective response to visceral sensations of pain and discomfort in IBS

BACKGROUND Typically, conventional functional imaging methods involve repeated exposures to sensory stimulation. In rectal distension (RD) studies that involve multiple distensions, however, it is difficult to disambiguate the central response to RD from pathological alterations in peripheral neural responses associated with relaxation and accommodation of the rectum. METHODS This study addressed potential confounders found in previous imaging studies by collecting functional magnetic resonance imaging studies (fMRI) data during a single slow ramp-tonic distension paradigm and analysing fMRI signal changes using independent component analysis. KEY RESULTS Compared with controls, IBS participants showed increased activation of the anterior cingulate cortices, insula and ventral medial prefrontal regions suggesting heightened affective responses to painful visceral stimuli. In addition, the failure by IBS patients to down-regulate activity within ventral medial prefrontal and the posterior cingulate/precuneus regions was suggestive of reduced sensitivity to somatic changes and delayed shifts away from rest in ;default network' activity patterns. Controls showed heightened activation of the thalamus, striatal regions and dorsolateral prefrontal cortex suggesting greater arousal and salience-driven sustained attention reactions and greater modulation of affective responses to discomfort and pain. CONCLUSION&INFERENCES This work points to alterations in the central response to visceral pain and discomfort in IBS, highlighting diminished modulation and heightened internalization of affective reactions.

Effect of IFN-beta therapy on the frequency and function of CD4(+)CD25(+) regulatory T cells and Foxp3 gene expression in relapsing-remitting multiple sclerosis (RRMS): a preliminary study

Interferon-beta (IFN-beta) is an immunomodulatory drug of choice to control relapsing-remitting multiple sclerosis (RR-MS), although its function is still unclear. A reduced suppressive function of CD4(+)CD25(+) regulatory T cells (T(reg)) has been shown in RR-MS patients. In this study, to understand the effect of IFN-ss on CD4(+)CD25(+) regulatory T cells, we analyzed the frequency and function of these cells and Foxp3 gene expression before and after treatment. We evaluated the frequency and function of CD4(+)CD25(+)Foxp3(+) regulatory T cells by flow cytometry and co-culture inhibition test respectively and gene expression of Foxp3 by real-time PCR in a longitudinal follow-up study in 18 relapsing-remitting MS patients. Our data revealed that IFN-beta significantly improved frequency and suppressive function of T(reg) cells (P<0.05) without any significant effect on gene expression of Foxp3 after 6 months. The results of the present study indicate that IFN-beta therapy in some of patients with RR-MS may restore function of regulatory T cells and control the unchecked immune cascade activity. Larger longitudinal studies on more MS patients are required to confirm our findings.

Mitochondrial mutation in Iranian patients with multiple sclerosis, correlation between haplogroups H, A and clinical manifestations

As multiple sclerosis (MS) has long been known to be associated with Leber, hereditary optic neuropathy (LHON), a disease caused by mitochondrial (mtDNA) mutations, in this study we assessed possible involvement of mtDNA point mutation in MS patients. Fifty-two MS patients whose disease was confirmed with revised McDonald criteria and referred to Iranian Center of Neurological Research of Imam Khomeini hospital during 2006-2007 entered the study. Secondary mtDNA mutations, age, gender, clinical disability according to expanded disability status scale (EDSS), course of the disease, and presenting symptoms were the variables investigated in this study. DNA purification was performed by Diatom DNA Extraction Kit. Analysis of data was done by SPSS V11.5. The prevalent mutations with frequency of 19.2% were J, L, and T haplogroups. Haplotype A was more prevalent in patients with younger age of onset (P-value = 0.012) and high proportion of haplogroup H was associated with optic nerve involvement (P-value = 0.015). No motor symptoms were seen in haplogroup H patients. There is no significant relationship between duration of the disease and EDSS in different mutation of mtDNA.

Involvement of kappa-opioid receptors in visceral nociception in mice

It has been shown that the behavioural responses to chemically evoked visceral nociception are increased in transgenic mice lacking the kappa-opioid receptor (KOR). The aim of the present study was to evaluate the contribution of KOR in mechanically evoked visceral pain by performing colorectal distension (CRD) and monitoring the subsequent visceromotor response (VMR) in control mice (KOR(+/+)) and in mice lacking KOR (KOR(-/-)). Pseudo-affective visceral pain responses were evoked in conscious mice using increasing (10-80 mmHg) and repeated (12 x 55 mmHg) phasic CRD paradigms. The resulting VMR was determined by monitoring the electromyographic activity of the abdominal muscle. The increasing and repeated CRD paradigms, respectively, evoked similar responses in both KOR(+/+) and KOR(-/-) mice. The selective KOR-agonists U-69593 (5 and 25 mg kg(-1), s.c.) and asimadoline (25 mg kg(-1), s.c.) significantly decreased the VMR in KOR(+/+) mice, while having no effect in KOR(-/-) mice. In contrast, the selective mu-opioid receptor agonist fentanyl significantly reduced the VMR in both types of mice and appeared more efficacious in KOR(-/-) mice. The opioid receptor antagonist naloxone (0.3-30 mg kg(-1) s.c.) did not affect the response to CRD in C57BL/6 mice at any dose tested. In conclusion, the data confirm that the KOR agonists used in this study inhibit the VMR to CRD in mice by acting via KOR receptors. In addition, the data suggest that the endogenous opioid system is not likely to modulate the VMR to mechanically evoked visceral pain in mice.

Vagal dysfunction in irritable bowel syndrome assessed by rectal distension and baroreceptor sensitivity

Autonomic nervous system dysfunction has been implicated in the pathophysiology of irritable bowel syndrome (IBS). This study characterized the autonomic response to rectal distension in IBS using baroreceptor sensitivity (BRS), a measure of autonomic function. Rectal bag pressure, discomfort, pain, ECG, blood pressure and BRS were continuously measured before, during and after rectal distension in 98 healthy volunteers (34 +/- 12 years old, 52 females) and 39 IBS patients (39 +/- 11 years old, 35 females). In comparison with the healthy volunteers, IBS patients experienced significantly more discomfort (69 +/- 2.2% vs 56 +/- 3.6%; P < 0.05), but not pain (9 +/- 1.4% vs 6 +/- 2.4%; ns) with rectal distension despite similar distension pressures (51 +/- 1.4 vs 54 +/- 2.4 mmHg; ns) and volumes (394 +/- 10.9 vs 398 +/- 21.5 mL; ns). With rectal distension, heart rate increased in both healthy volunteers (66 +/- 1 to 71 +/- 1 bpm; P < 0.05) and IBS patients (66 +/- 2 to 74 +/- 3 bpm; P < 0.05). Systolic blood pressure also increased in both healthy volunteers (121 +/- 2 to 143 +/- 2 mmHg; P < 0.05) and patients (126 +/- 3 to 153 +/- 4 mmHg (P < 0.05) as did diastolic blood pressure, 66 +/- 2 to 80 +/- 2 mmHg (P < 0.05), compared with 68 +/- 3 to 84 +/- 3 mmHg (P < 0.05) in IBS patients. The systolic blood pressure increase observed in IBS patients was greater than that seen in healthy volunteers and remained elevated in the post distension period (139 +/- 3 mmHg vs 129 +/- 2 mmHg; P < 0.05). IBS patients had lower BRS (7.85 +/- 0.4 ms mmHg(-1)) compared with healthy volunteers (9.4 +/- 0.3; P < 0.05) at rest and throughout rectal distension. Greater systolic blood pressure response to rectal distension and associated diminished BRS suggests a compromise of the autonomic nervous system in IBS patients.

Distension-induced gastric accommodation in functional dyspepsia: effect of autonomic manipulation

Functional dyspepsia (FD) is associated with impaired gastric accommodation and autonomic dysregulation. The aim of this study was to investigate the effects of autonomic manipulation on distension-induced gastric accommodation in subjects with and without FD, using a newly developed gastric barostat paradigm. Twelve healthy subjects (HS) and 18 subjects with FD had four barostat examinations each: no intervention, intravenous atropine (1 mg), vagal stimulation (mental relaxation with deep breathing) and acute stress stimulation (serial subtraction task). Intrabag pressure increased from 1 to 15 mmHg in 5 min (ramp phase), and was maintained at 15 mmHg for 5 min (tonic phase). Volume responses were analysed using predefined parameters. There were no significant group differences in accommodation variables between HS and subjects with FD. The FD group could be subdivided into two distinct subgroups: subgroup 1 (n = 7, 38%) with low maximum volume and accommodation rate, and subgroup 2 with normal accommodation (n = 11). In subgroup 1, but not in subgroup 2 atropine increased maximum volume and accommodation rate substantially. Neither mental stress nor mental relaxation changed any of the accommodation variables. In a subgroup of subjects with FD, impairment of distension-induced gastric accommodation can be improved by cholinergic blockade, but not by acute physiological autonomic manipulation.

A new intelligent distension system for hollow organs

Controlled distension of hollow organs is an accepted technique for generating reproducible visceral stimuli. We have constructed a new, flexible and intelligent distension system in which discomfort, pain and autonomic responses are recorded online. These responses can be fed back into the system in a regulatory loop and be used to shape the distension paradigm. Consequently, it is possible to take all subjects to a state of equal, although subjective, level of discomfort or pain, even though pressure, tension and volume might be totally different. By using a variable airflow, this new distension system can be effectively used in all kinds of paradigms, e.g. phasic, tonic, or ramp distensions or customized combinations of them. The system can be used to control pressure, volume or tension. A refinement of the system is that it is possible to automatically change the controlled entity during a distension, e.g. from an isobaric ramp directly into an isovolumetric tonic phase. Furthermore, the distension device allows double distensions with independent distension paradigms.

CRF2 receptor activation prevents colorectal distension induced visceral pain and spinal ERK1/2 phosphorylation in rats

BACKGROUND AND AIMS

Activation of corticotropin releasing factor 1 (CRF1) receptors is involved in stress related responses and visceral pain, while activation of CRF2 receptors dampens the endocrine and some behavioural stress responses. We hypothesised that CRF2 receptor activation may influence visceral pain induced by colorectal distension (CRD) in conscious rats, and assessed the possible sites and mechanisms of action.

METHODS

Male Sprague-Dawley rats were exposed to CRDs (60 mm Hg, 10 minutes twice, with a 10 minute rest interval). Visceromotor responses (VMR) were measured by electromyography or visual observation. Spinal (L6-S1) extracellular signal regulated kinase 1/2 (ERK 1/2) activation following in vivo CRD and CRF2 receptor gene expression in the T13-S1 dorsal root ganglia (DRG) and spinal cord were determined. Inferior splanchnic afferent (ISA) activity to CRD (0.4 ml, 20 seconds) was assessed by electrophysiological recording in an in vitro ISA nerve-inferior mesenteric artery (intra-arterial)-colorectal preparation.

RESULTS

In controls, VMR to the second CRD was mean 31 (SEM 4)% higher than that of the first (p<0.05). The selective CRF2 agonist, human urocortin 2 (hUcn 2, at 10 and 20 microg/kg), injected intravenous after the first distension, prevented sensitisation and reduced the second response by 8 (1)% and 30 (5)% (p<0.05) compared with the first response, respectively. RT-PCR detected CRF2 receptor gene expression in the DRG and spinal cord. CRD (60 mm Hg for 10 minutes) induced phosphorylation of ERK 1/2 in neurones of lumbosacral laminae I and IIo and the response was dampened by intravenous hUcn 2. CRD, in vitro, induced robust ISA spike activity that was dose dependently blunted by hUcn 2 (1-3 microg, intra-arterially). The CRF2 receptor antagonist, astressin2-B (200 microg/kg subcutaneously or 20 microg intra-arterially) blocked the hUcn 2 inhibitory effects in vivo and in vitro.

CONCLUSIONS

Peripheral injection of hUcn 2 blunts CRD induced visceral pain, colonic afferent, and spinal L6-S1 ERK 1/2 activity through CRF2 receptor activation in rats.

Altered neuroendocrine response and gastric dysmotility in the Flinders Sensitive Line rat

In the search for animal models that can replicate some features of functional dyspepsia (FD) patients, we turned our interest to the Flinders Sensitive Line (FSL) rat. Gastric motility disturbances prevalent in FD patients as well as urine corticosterone and plasma prolactin were measured following buspirone challenge. Flinders Resistant Line (FRL) rat was used as control. The results show that the FSL rats have a disturbed gastric motility, reflected as both an increased gastric accommodation rate and gastric volume during gastric distension as well as a delayed gastric emptying, the latter possibly as a consequence of the former. Lipid administration resulted in a significant increase in maximal gastric volume only in the FRL rats. Both the corticosterone response to buspirone and the 24-h urinary output of corticosterone were normal in FSL rats. Similar to FD patients, the FSL rat showed supersensitivity to buspirone in the increase in prolactin release. Although FSL rats show some features similar to a subset of FD patients, the increased gastric accommodation contrasts to the reduced accommodation often seen in FD patients. Further studies are warranted to determine the relevance of this rat strain as a model for FD.

A model for chronic quantitative studies of colorectal sensitivity using balloon distension in conscious mice -- effects of opioid receptor agonists

In the current study, colorectal distension (CRD) was performed in conscious mice, in order to study visceral (colon) sensitivity. Electrodes were chronically implanted into the external oblique muscle to obtain the electromyographic (EMG) response to CRD. CRD was performed using a computerized system, which inflated the balloon with air to the desired pressures. An increasing (10-80 mmHg) and a repeated (12 x 55 mmHg) phasic paradigm with distensions lasting 10 s and with 5-min intervals were used. The EMG recordings were linearly correlated to intracolonic pressures between 10 and 80 mmHg, which are characteristic of the visceromotor response (VMR). Repeated phasic distensions at 55 mmHg resulted in a stable VMR in female mice, but an increasing VMR in male mice. Interestingly, the duration of the VMR was about 5 s, which is shorter than the actual duration of the distension. U-69593 and fentanyl (selective kappa and mu opioid receptor agonists) significantly reduced the VMR at subcutaneous doses of 0.5 and 0.05 mg x kg-1, respectively. In conclusion, a CRD model for repetitive quantitative studies of colorectal sensitivity and evaluation of pharmacological modulation of visceral sensitivity in conscious mice is presented.

Osmotic diuretics and hemodilution in postischemic renal failure

In the acute phase of ischemic renal failure, the severe depression of the glomerular filtration rate (GFR) is due to obstruction of the tubules by cells and cell debris rejected from the proximal tubules, a blockade which can be prevented at least partly, by treatment with osmotic diuretics. The isosthenuria, the second typical sign in ischemic acute renal failure, probably derives from the medullary ischemia that results from an intracapillary trapping of red cells. This, in turn, is suggested to be caused by oxygen-derived free radicals, which via increasing the capillary macromolecular permeability result in a massive extravasation of plasma and hence in hemoconcentration. As expected from this hypothesis, scavengers may ameliorate both the trapping and the consequent medullary ischemia. Unfortunately, however, a therapy using both osmotic diuretics and scavengers fails to improve the long-term outcome. Hemodilution would seem more promising, since it will both prevent the medullary ischemia seen in the acute phase and substantially improve the long-term outcome. At a hematocrit of 0.30, rat kidneys exposed to 45-min ischemia will show a GFR 1 month after the insult of more than 50% of the normal GFR as against 15% in untreated animals.

Oxygen radicals in postischaemic damages in the kidney

Oxygen radicals in postischaemic damages in the kidney: M. Wolgast, A. Bayati, O. Hellberg, O. Källskog, K. Nygren and G. Ojteg, Inst. of Physiology and Medical Biophysics, University of Uppsala, Sweden; Ischemic acute renal failure is characterized by a severe depression of the glomerular filtration rate (GFR), isosthenuria and deficient potassium secretion, whereas the total renal blood flow may remain largely intact. As to these symptoms, it would seem established that the depression of GFR results from an ischaemia-induced augmented aging and hence rejection of tubular cells, which thence blocks the tubular lumen. As expected this blockade can be prevented by osmotic diuretics. The isosthenuria and the deficient potassium excretion, on the other hand, results probably from a medullary ischaemia, the latter due to the action by oxygen-derived free radicals in the sense the subsequent damage to the capillary membrane leads to a massive extravasation of plasma and consequent intracapillary trapping of red cells. In line with this idea, superoxide-dismutase (SOD) or Allopurinol may ameliorate these changes. In the recovery phase of postischaemic renal failure, the most prominent feature is the blocking of the ascending loop of Henle with Tamm/Horsfall-protein which, if not washed-out during the first week, leads to a complete degeneration of the nephron. Unfortunately, the process would seem to be unaffected by treatment with e.g. osmotic diuretics and SOD or Allopurinol.

The effect of loop diuretics on the long-term outcome of post-ischaemic acute renal failure in the rat

The effects of continuous treatment with loop-acting diuretics on the long-term functional and histopathological outcome in kidneys subjected to 45 min of warm ischaemia were studied. One month after the primary damage the inulin clearance in the untreated kidneys was 0.44 +/- 0.05 ml min-1, improving significantly to 0.69 +/- 0.11 ml min-1 in furosemide-treated animals and to 0.75 +/- 0.09 ml min-1 in those treated with piretanide. Urine osmolality increased from 986 +/- 89 mosmol kg-1 in the untreated animals to 1479 +/- 195 mosmol kg-1 in the furosemide-treated ones. At the same time the total area of the outer medulla occupied by Tamm-Horsfall protein cylinders decreased from 7.0 +/- 1.2% in the untreated animals to 3.6 +/- 0.52% in the treated ones. It is concluded that by decreasing the number of nephrons blocked by Tamm-Horsfall cylinders an improvement in the function of ischaemically damaged kidneys can be achieved. This blockade, also called secondary damage, is of critical prognostic importance for the long-term outcome of the ischaemic renal failure. Treatment of the animals with loop diuretics decreased the occurrence of these cylinders, leading to an improvement of kidney function I month after the primary damage, this despite the fact that the primary damage seen in the early recirculation period was not treated specifically.

Red cell trapping after ischemia and long-term kidney damage. Influence of hematocrit

The influence of the hematocrit (Hct) on the trapping of red blood cells (RBC) in the renal microvasculature and its effect on the long-term outcome following unilateral ischemia were investigated in the rat. The results showed that an increase in the duration of ischemia increased the RBC trapping, as measured by 51Cr-labeled erythrocytes, in a dose-dependent manner. At normal Hct (46%) the period of ischemia producing half-maximum RBC trapping was 45 minutes, whereas after hemodilution (Hct = 31%) or hemoconcentration (Hct = 60%) the corresponding periods were 80 and 25 minutes, respectively. Regarding the long-term outcome, 45 minutes of ischemia with a normal Hct was associated with a marked decrease in kidney weight, GFR and urine osmolarity after four weeks of recovery, which could be prevented to a large extent by hemodilution. Conversely, with hemoconcentration there was severe damage after only 25 minutes of ischemia. It is suggested that these long-term effects are attributable to RBC trapping in the microvasculature of the outer medulla, which may cause added ischemia in this area of the kidney. It is also suggested that cortical atrophy is secondary to the medullary injury, and is brought about to avoid extensive water and salt losses.

A study in the maintenance phase of ischaemic acute renal failure in the rat

The fate of the trapped deformed erythrocytes seen in the early recirculation phase after ischaemia and the generation of long Tamm-Horsfall (TH) cylinders in the renal medulla during the first week after recirculation was studied in rats. In an in-vitro study the effects of different concentrations of TH protein on the permeability to Na+ of a semipermeable membrane were also investigated. The trapping of erythrocytes was found to be a reflow phenomenon, as there was no increase in the capillary area of the medulla in kidneys subjected to ischaemia but with no recirculation. This area increased to a maximum of 34.6 +/- 2.07% 20 min after recirculation and decreased to a normal value of 3.3 +/- 0.74% 1 day after the primary ischaemia. The area occupied by cylinders increased to a maximum of 19.2 +/- 1.4% 2 days after the primary damage and was as large as 16.7 +/- 1.47% after 1 week. It was also shown that the diffusion half-time of Na+ ions across a semipermeable membrane increased from 11.4 +/- 0.45 min to a maximum of 32.2 +/- 2.19 min with a protein concentration of 1 mg ml-1. It was concluded that the trapping of erythrocytes alone could not explain the decrease in renal function 1 week after the primary damage, but that the blockade of the tubules by the long homogeneous TH cylinders could be responsible for this decrease.

Mechanism of erythrocyte trapping in ischaemic acute renal failure

Forty-five minutes of warm ischaemia and 20 min of recirculation in the rat kidney was found to result in (1) a massive transient extravasation of plasma upon recirculation and (2) an increase in plasma-lymph transport of proteins during the first hours after onset of circulation. This was accompanied by trapping of erythrocytes, as determined with 51Cr-labelled erythrocytes, in the capillaries, mainly in the inner stripe of the outer medulla. At scanning electron microscopy of vibratome sections, the trapping appeared as aggregates of polygonally shaped erythrocytes. It is concluded that 45 min of ischaemia and 20 min of recirculation results in an increase in the permeability of the renal capillaries. This increase leads to extravasation of capillary plasma with consequent local haemoconcentration, causing an increase in vascular resistance and in capillary hydrostatic pressure. This elevated pressure will, in turn, lead to perpetuating extravasation of plasma, further haemoconcentration and so on, eventually resulting in dense packing of polygonal erythrocytes, obstructing the blood flow. It is believed that oxygen-derived free radicals generated in the early recirculation phase contribute to the increase in macromolecular permeability, since the scavenger bovine superoxide dismutase and allopurinol, a xanthine oxidase inhibitor, were found to prevent this unfavourable chain of events.

The long-term outcome of post-ischaemic acute renal failure in the rat. II. A histopathological study of the untreated kidney

Histopathological changes in kidneys subjected to 45 min of isothermic unilateral ischaemia in the acute phase and 1 week and 1 month after primary damage were studied at the electron microscopic level. During the first week after recirculation long homogeneous cylinders, probably consisting of Tamm-Horsfall protein, developed in the medullary parts of the nephron, and after 1 month of recirculation there were two types of nephrons: (1) nephrons with a normal histological appearance and (2) degenerated nephrons. The latter group gave rise to crypts in the outer cortical area. It is hypothesized that the generation of the long Tamm-Horsfall cylinders in the thick ascending limb of the loop of Henle plays an important role in the long-term outcome of the kidney after the primary damage. The persistent blockade caused by these cylinders will lead to precipitation of the ultrafiltrate, resulting in long cell-protein cylinders in the proximal parts of the nephron. This precipitation will proceed in the retrograde direction, reaching the mother glomeruli, eventually leading to total degeneration of the nephron.

The long-term outcome of post-ischaemic acute renal failure in the rat. I. A functional study after treatment with SOD and sucrose

The long-term outcome in rat kidneys subjected to 45 min of warm ischaemia with no treatment and after administration of 20 mg superoxide dismutase (SOD) and of SOD combined with 2 ml of a 12% sucrose solution was studied by the micropuncture technique. It was found that, although in the acute phase SOD prevented trapping of erythrocytes in the medullary vasculature and that SOD + sucrose also prevented the formation of tubular obstruction, the long-term results as studied 1 week and 1 month after the primary ischaemic insult were virtually identical. This was due to the formation of new obstructions, during the first week, mainly in the thick ascending limb of Henle's loop. After 1 month the proximal tubular free-flow pressure and the single-nephron filtration rate had returned to normal. However, since the total glomerular filtration was only one-third of that under normal conditions, it would seem that two-thirds of the nephrons had undergone complete degeneration. This degeneration was probably the result of persistent tubular obstruction. The tubular degeneration was also accompanied by a reduction in urine osmolality and potassium secretion.

Plasma elimination kinetics and renal handling of copper/zinc superoxide dismutase in the rat

The renal handling of bovine and human superoxide dismutase (SOD) was investigated in Sprague-Dawley and Munich-Wistar rats. Under normal physiological conditions the half-time of the major rapid component of the plasma elimination curve was estimated at 6.0 +/- 0.5 min, the volume of distribution at 35.7 +/- 3.3 ml kg-1, i.e. the plasma volume and the corresponding plasma clearance at 4 ml min-1 kg-1. After a single intravenous dose, most of the enzyme was distributed to and eliminated by the two kidneys, whereas the non-renal clearance was low, 0.5 ml min-1 kg-1. The single nephron filtration of SOD, as assessed from micropuncture of Bowman's space, was 10.4 +/- 1.0 nl min-1, which was 26 +/- 2% of that for inulin. The total elimination of SOD by glomerular filtration would thereby be 2.5 ml min-1 kg-1, i.e. the glomerular ultrafiltration process would account for the largest part of the elimination of SOD from circulating plasma. After the dosage of 20 mg kg-1, about two-thirds of the injected SOD was excreted as the intact molecule into the urine, whereas one-third was found to be reabsorbed and metabolized by the proximal tubular epithelial cells. In animals suffering from unilateral post-ischaemic acute renal failure, the elimination half-time was 13 +/- 1.9 min, a value which increased by 55 +/- 5 min after bilateral functional nephrectomy. By contrast, the distribution volume remained essentially unchanged.

Tissue distribution of 125I-labelled bovine superoxide dismutase (SOD) in the rat

Bovine copper/zinc superoxide dismutase (SOD) was labelled with 125I using the chloramine-T method. The tissue distribution of 125I-SOD (dose of SOD 5 mg/kg) was studied with whole-body and microautoradiography at various times after an intravenous injection. The distribution of 125I-SOD showed a remarkable organ specificity in that the localization of the enzyme to the kidneys and the urinary tract completely dominated the autoradiograms. The time pattern of localization of 125I-SOD also gives a clear picture of the renal handling of the enzyme in that, as a consequence of the renal elimination, the enzyme rapidly disappears from the circulation with an elimination half time of about 6 min. Up to 20 min. after the injection, there were high concentrations of 125I-SOD in the renal pelvis, ureter and urinary bladder showing that in addition to renal uptake there was an initial substantial urinary excretion of the enzyme. From the microautoradiography it is clear that the grains were exclusively localized over proximal tubular cells and tended to be concentrated at the luminal rather than the peritubular side of tubule. This would be compatible with renal uptake secondary to glomerular filtration of 125I-SOD, which is what one would expect from the renal handling of a protein with a molecular weight around 31,000 and an isoelectric point around pH 5.4. Pretreatment with a large dose of SOD (88 mg/kg) tended to competitively decrease the renal uptake of labelled SOD after 5 min. and apparently further increase its renal excretion. However, a noticeable renal uptake of 125I-SOD was still apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of ischaemic acute renal failure with superoxide dismutase and sucrose

The preventive effects of intravenously administered superoxide dismutase (SOD) and of SOD combined with sucrose on acute renal failure were investigated in rat kidneys exposed to 45 min of warm ischaemia. Superoxide dismutase (20 mg) given just before primary ischaemia and in the early recirculation phase was found to ameliorate the red cell aggregation in the renal medulla, in particular, in the inner stripe of the outer zone the volume of trapped red cells decreased from 11.2 +/- 1.6% in untreated animals to 0.02 +/- 0.001%, thus allowing improved restoration of medullary blood flow. This was also accompanied by an expected restoration of the urine osmolality reaching almost 400 mOsm kg-1 after administration of SOD + sucrose. Superoxide dismutase also restored the capillary macromolecular permeability as evidenced by normalization of plasma to lymph transport of proteins. Micropuncture studies showed that in ischaemically damaged but untreated kidneys the tubules were obstructed and that the proximal tubular pressure rose to such a level that the net driving force for filtration approached zero. This explains the marked decrease in glomerular filtration rate (GFR) from a normal value of about 1 ml min-1 to 0.01 +/- 0.02 ml min-1. After treatment with SOD the tubules were still largely obstructed, resulting in a depression of the net driving force and a decrease in single nephron glomerular filtration rate (SNGFR) to about 11 nl min-1, that is, to only 25% of the normal SNGFR. The total filtration was 0.09 +/- 0.04 ml min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal capillary permeability and intravascular red cell aggregation after ischaemia. I. Effects of xanthine oxidase activity

The macromolecular permeability of renal capillaries and the intravascular red cell aggregation resulting from 45 min of warm ischaemia were investigated. The effects of the xanthine oxidase inhibitor Allopurinol on these factors and also on the post-ischaemic nephron function were also studied. Following ischaemia there was a more than 10-fold increase in the transport from plasma to renal hilar lymph both of plasma proteins and of two isomers of lactate dehydrogenase (LDH)-the nearly neutral LDH-M4 and the negatively charged LDH-H4. The ischaemia also resulted in massive intravascular red cell aggregation, especially in the renal medulla. Through reduction of plasma xanthine oxidase activity from 13.1 +/- 1.1 microU microliter-1 (mean +/- SEM) to essentially zero by Allopurinol, the capillary leakiness was substantially diminished with almost complete normalization after 120 min. At the same time the relative volume of trapped red cells was reduced; in the inner stripe of the outer medulla, for example, it decreased from 11.3 +/- 1.7% in untreated animals to 4.0 +/- 1.1% after treatment with 20 mg of Allopurinol given intravenously 3 h before the ischaemia. Oral feeding with 4 mg of Allopurinol day-1 for one week gave essentially the same result. The net driving force for filtration after treatment with this drug was thus 19 mmHg, as against 26 mmHg in the normal kidney and the resulting SNGFR was half the normal. The total filtration rate was proportionally more reduced to less than 1/3 of the normal. Tubular obstruction was still present but was not as severe as in untreated kidneys (Karlberg et al., 1982b) where the tubular fluid flow and thereby the filtration are essentially zero. It is suggested that oxygen free radicals increased the macromolecular permeability and the adhesiveness of white blood cells and that these two factors combined underlie the aggregation of red blood cells in the medullary vasa recta with consequent persistence of medullary ischaemia.