[Acute kidney failure in critically ill patients and its prevention]

Acute renal failure often complicates the course of critically illness and can contribute to high morbidity and mortality. In most cases acute renal failure represents a part of the multiple organ dysfunction syndrome and it is usually related to the ischemic and/or toxic injury of tubular cells (acute tubular necrosis, ATN). The presented paper reviews the mechanisms involved in this two types of tubular cells injury. It analyzes the measures of kidney protection during critical illness, which include optimization of systemic and intrarenal hemodynamics as well as avoidance of nephrotoxic drugs. It describes the most common nephrotoxic drugs and proposes principles of their safer use. Potential strategies to stimulate kidney function recovery are also discussed.

[Gene therapy of pain]

Possible practical applications of gene therapy for pain are at the beginning. Very intensive research on animal models has been effectuated and some partial results of clinical applications in men already exist. The article describes different possibilities of these applications, namely the application of viral vectors and antisense nucleotides as well as the first experimental results of possible gene therapy. BDNF (brain derived nervous factor), herpes simplex virus, cytokine-interleukin 10, viral mediated transfer of the decarboxylase of the glumatic acid and down--regulated genes are recently used. Experimation of beta endorphin is also possible. In the article describes also possible molecular and gene therapy of pain and the molecular neurosurgical approach to the treatment of pain, which is called the molecular neurosurgery. From all these results it is possible to conclude, that gene therapy will be definitely used for the treatment of pain and that only the intensive research in this field may bring some important results.

Differences in hormonal and inflammatory parameters in male Lewis and Long Evans rats with adjuvant arthritis

The purpose of the present study was (i) to compare secretory responses of prolactin and corticosterone to the acute stress of immobilization in male rats of the Lewis and Long Evans strains and (ii) to compare secretion of the two hormones in rats with fully developed adjuvant arthritis (AA) and their relationship with the intensity of the inflammatory reaction. A short immobilization of 5 min induced equal elevations of both hormones in both strains, but 20-min immobilization produced significantly stronger responses in Long Evans rats than in Lewis rats. AA inhibited prolactin secretion equally in both strains (from 11.6 +/- 1.3 ng/ml to 4.2 +/- 0.6 ng/ml in Lewis rats, p < 0.01, and from 3.7 +/- 0.6 to 2.12 +/- 0.1 ng/ml in Long Evans rats, p < 0.05), but caused a conspiciously larger elevation of corticosterone in the Long Evans than in the Lewis animals (11.5 +/- 1.2 microg/dl in Long Evans rats versus 5.1 +/- 0.5 microg/dl in Lewis rats, p < 0.01) while basal levels were similar. The larger corticosterone response in the Long Evans rats was associated with a stronger inflammatory reaction assessed by hind paw swelling (2.3 +/- 0.1 ml for Long Evans rats versus 1.8 +/- 0.08 ml for Lewis rats, p < 0.01) and plasma levels of nitric oxide (47.5 +/- 5.7 microM for Long Evans rats versus 28.7 +/- 2.5 microM for Lewis rats, p < 0.01) than in the Lewis males with lower corticosterone levels. In conclusion, there are significant, obviously genetically based, differences in the corticosterone responses to both immobilization and AA between the two strains, with the Long Evans rats reacting more strongly than the Lewis rats. The lack of the expected inverse relationship between corticosterone levels and the intensity of the inflammation indicates that the activity of corticosterone is not its primary determinant and that other important factors are involved.

Effect of prone position on hepato-splanchnic hemodynamics in acute lung injury

OBJECTIVE

To evaluate the effects of prone position on hepato-splanchnic hemodynamics, metabolism and gut mucosal energy balance.

DESIGN

Prospective clinical study.

SETTING

Medical intensive care unit in a university hospital.

PATIENTS

Eleven hemodynamically stable patients with acute lung injury (ALI) requiring mechanical ventilation.

INTERVENTION

Patients were studied in the supine position, after 90 min in the prone position and after 90 min of supine repositioning.

MEASUREMENTS AND RESULTS

In addition to global hemodynamics we measured intra-abdominal pressure (IAP, bladder), hepato-splanchnic blood flow (HSBF, steady state indocyanine green technique using a hepatic vein catheter) and gastric mucosal-arterial PCO(2) gap (PCO(2) gap, automated air tonometry). Systemic hemodynamics did not change during the whole study. Prone positioning did not significantly affect IAP. HSBF as well as splanchnic oxygen consumption remained unaltered, too. Similarly, neither liver lactate uptake nor indocyanine green extraction were influenced by positional changes. Finally, stable regional hemodynamics were accompanied by an unchanged PCO(2) gap.

CONCLUSION

We conclude that if IAP and systemic hemodynamics remain unaffected, the prone position in ALI patients compromises neither hepato-splanchnic perfusion nor gastric mucosal energy balance.

Continuous venovenous hemofiltration: effects on monocyte and lymphocyte immunophenotype in critically ill patients

The aim of this study was to test the hypothesis that continuous venovenous hemofiltration (CVVH) increases HLA-DR expression on monocytes and T lymphocytes in critically ill patients. 24 septic (SP) and 10 non-septic (NSP) medical ICU patients with acute renal failure were studied prospectively. The ultrafiltration rate was 20-30 ml.kg(-1).h(-1). The total and differential white cell counts were measured and CD3+ lymphocyte count, HLA-DR expression on CD14+ monocytes and CD3+ lymphocytes were analysed by two-colour flow cytometry before, 4 and 24 h after CVVH initiation, respectively. CVVH did not influence leukocyte, granulocyte, total lymphocyte and CD3+ lymphocyte counts in both groups of patients. The percentage of HLA-DR+/CD14+ monocytes in SP revealed no changes, whereas it decreased after 4 h of CWH in NSP (p < 0.05). The percentage of HLA-DR+/CD3+ lymphocytes in SP decreased after 24 h (p < 0.05), whereas it remained unchanged in NSP. We conclude that CWH initiation is not associated with the increase of HLA-DR expression on CD14+ monocytes and T lymphocytes in critically ill patients with acute renal failure.

[Fluid resuscitation in conditions with disorders of capillary permeability]

Fluid resuscitation remains a cornerstone in the treatment of various types of circulatory failure. Alterations in microvascular permeability are a hallmark of a number of inflammatory conditions including sepsis, septic shock, burns and the acute respiratory distress syndrome. As a result, the loss of plasma fluid into the interstitial space leads to hypovolaemia and tissue hypoperfusion. Administration of large volumes of fluids in often necessary to restore the nutritional blood flow to tissues. This strategy, however, involves the risk of interstitial edema formation, which in turn may further impair tissue oxygen distribution. The presented paper briefly reviews the principles of transvascular fluid exchange and the pathophysiology of capillary permeability. It discusses the ongoing controversy on the optimal way and the end points of volume replacement as well as the choice of fluid in conditions associated with capillary leakage.

[Free radicals and antioxidants in cerebrospinal fluid in central nervous system diseases]

Free radicals and antioxidants may play a role in the etiology and pathogenesis of some central nervous diseases. The brain tissue is relatively insufficiently protected by antioxidants against the free radical induced damage. The brain situation may be reflected by the cerebrospinal fluid examination, which has not enough attention. It seems, that from this point of view subarachnoical hemorrhagy, meningitis, hydrocephalus, Alzheimer's, Parkinson's and Huntington's diseases, multiple sclerosis and probably schizophrenia should receive a special attention.

Does exogenous melatonin influence the free radicals metabolism and pain sensation in rat?

Melatonin has been shown to play a role in antioxidative defence. We therefore studied its effect on oxidative damage to the rat cerebral cortex evoked by painful stimulation and immobilization-induced stress. Moreover, the effect of melatonin on chronic pain perception was examined. Rats were injected with either a high dose of melatonin (100 mg/kg i.p.) or a vehicle for five days and were subjected to painful stimulation or immobilization stress 30 min after the treatment. To determine the degree of oxidative stress, the levels of free radicals, thiobarbituric acid reactive substances (TBARS) as indicators of lipid peroxidation and glutathione peroxidase (GSHPx) were estimated in somatosensory cortex. Pain perception was measured by the tail-flick and plantar test. Melatonin reduced the level of TBARS previously increased by painful stimulation. Melatonin also exhibited a slight analgesic effect in those animals exposed to painful stimulation but its role in free radical scavenging did not contribute to this effect.

Submaximal exercise in healthy volunteers: the relationship between gastric mucosal and systemic energy status

The effect of exercise on gastric mucosal energy status has not been fully elucidated. The aim of this study was to evaluate the impact of submaximal cycling on gastric mucosal energy balance and its relationship to changes in systemic energy status. Ten healthy volunteers (age 20-40 years) were investigated at rest (BL), during 30 min of submaximal exercise (E) on bicycle ergometry and during the 30 min after the completion of cycling. Gastric mucosal PCO(2) ( P(gm)CO(2)) was measured by air tonometry at 10-min intervals and the gastric mucosal-arterial PCO(2) difference ( PCO(2)gap) was calculated. Hemodynamics, arterial blood gases, lactate and pyruvate were also measured. PCO(2)gap significantly increased throughout exercise [BL: 0.2 kPa (median), -0.1-0.6 kPa (25th-75th percentiles); E(10 min): 1.0 kPa, 0.8-1.7 kPa; E(20 min): 1.35 kPa, 0.8-1.8 kPa; E(30 min): 1.5 kPa, 0.9-2.0 kPa]. The early changes in PCO(2)gap ( PCO(2)gap at E(10 min) minus PCO(2)gap at BL) correlated significantly and positively with corresponding changes in arterial lactate ( r(2)=0.58, P<0.05) and lactate-to-pyruvate ratio ( r(2)=0.72, P<0.05). On recovery, all metabolic parameters normalized within 30 min. We conclude that submaximal cycling in volunteers leads to the early derangement of gastric mucosal energy balance. The time course of PCO(2)gap parallels changes in systemic energy status.

[Gastrointestinal tract dysfunction in critical illness]

Until relatively recently, the gastrointestinal (GI) tract was considered a dormant, metabolically and immunologically inactive organ in critically illnesses. However, the GI tract provides a number of crucial functions that, in fact, may influence morbidity and mortality of many critically ill patients. Its large absorptive area provides a site for nutrient digestion and utilization and serves as an important barrier preventing the systemic absorption of intraluminal microbes and its toxic products. Moreover, the GI tract is the largest reservoir of lymphocytes in the body, which significantly contribute to the immune response of the critically ill patients. The gut dysfunction occurs frequently and early in the intensive care patients. Abnormal colonization, impaired intestinal epithelial barrier function and bacterial translocation represent the key components of gut failure implicating in the pathogenesis of sepsis and multiorgan dysfunction. This review summarizes recent insights into the role of the gut in critically ill patients with particular focus on 1) the basis of "gut-origin hypothesis", 2) pathophysiology of gut dysfunction, 3) monitoring of intestinal function, and 4) protective measures and novel therapeutic strategies.

The postnatal development of tail-flick latencies to acute and repeated stimulation in the rat

The development of the reaction to thermal nociceptive stimulation was studied in neonatal rats of two strains (albino Wistar and pigmented Long-Evans). Using the tail-flick method in neonates of both strains the effects of daily repeated thermal stimulation (sensitisation) were compared to those of acute stimulation applied on 1 day only. During the whole postnatal development period studied (3-28 days) the pigmented rat pups were more sensitive to a repeated thermal nociceptive stimulation than the albinos. The latency of the response did not change linearly during the developmental time studied, but had a pronounced peak (decreased sensitivity) in the period of eye-lid opening. In the pigmented animals the peak appeared 1 day earlier than in the albinos. At the time of the weaning period the latencies of the response were again shorter.

[Extravascular lung water in acute respiratory distress syndrome: pathophysiology, monitoring and therapeutic possibilities]

Excessive amount of extravascular lung water (EVLW) resulting from increased permeability of alveolo-capillary membrane is a pathophysiological hallmark of acute respiratory distress syndrome (ARDS). Increased EVLW produces hypoxemia by interference with gas exchange. During shock resuscitation, in disorders in which microvascular endothelial integrity is impaired, large volumes of intravenous fluids needed to restore tissue perfusion may also be associated with the risk of increased accumulation of EVLW. The presented paper briefly reviews the mechanisms involved in lung edema formation and describes current options to measure EVLW. In addition, it discusses clinical implications of EVLW measurement in intensive care setting with particular focus on transpulmonary indicator dilution technique.

Effects of ultrafiltration, dialysis, and temperature on gas exchange during hemodiafiltration: a laboratory experiment

To study gas exchange in the filter during continuous venovenous hemodiafiltration (CVVHDF), an air-tight heated mixing chamber with adjustable CO2 supply was constructed and connected to a CVVHDF monitor. Bicarbonate-free crystalloid (Part 1) and packed red blood cell (Part 2) solutions were circulated at 150 ml x min(-1). Gas exchange expressed as pre-postfilter difference in CO2 and O2 contents was measured at different CVVHDF settings and temperatures of circulating and dialysis solutions. Ultrafiltration was most efficacious for CO2 removal (at 1,000 ml x h(-1) ultrafiltration CO2 losses reached 13% of prefilter CO2 content). Addition of dialysis (1,000 ml x h(-1)) increased CO2 loss to 17% and at maximal parameters (filtration 3,000 ml x h(-1), dialysis 2,500 ml x h(-1)), the loss of CO2 amounted to 35% of prefilter content. Temperature changes of circulating and/or dialysis fluids had no significant impact on CO2 losses. The O2 exchange during CVVHDF was negligible. Currently used CVVHDF is only marginally effective in CO2 removal. Higher volume ultrafiltration combined with dialysis can be expected to reach clinical significance.

Stress of chronic food restriction attenuates the development of adjuvant arthritis in male Long Evans rats

OBJECTIVE

To study the effect of the stress of chronic food restriction on the development of adjuvant arthritis in Long Evans male rats.

METHODS

Four groups of animals were compared: non-treated control (C) and arthritic (AA) rats, both with free access to food and water and two analogous groups with a 40% food restriction, i.e. non-treated (FR) and arthritic (AA-FR) animals. All rats were killed 22 days following the injection of complete Freund's adjuvant. The parameters measured were: serum levels of albumin (ALB), nitrate, glucose, insulin, corticosterone (CORT), prolactin (PRL) and PRL mRNA in the adenopituitaries. In addition the activity of gamma-glutamyl transpeptidase (GGTP) was measured in the spleen. The pain threshold was determined by the tailflick method. The body weight of the animals was recorded on day 0, 3, 7, 11, 15 and 18 of the disease.

RESULTS

Arthritis caused swelling of the hind paw (2.37 +/- 0.15 ml vs 1.1 +/- 0.05ml in controls, p < 0.01) which was prevented in the AA-FR group (1.44 +/- 0.13 ml, not significant against controls). Arthritis increased serum NO and reduced ALB levels; both changes were significantly restored in the FR-AA group. Food restriction did not alter the activation of GGTP, or the decrease of PRL mRNA observed in the AA group. Serum CORT was elevated in rats with food restriction (15.49 +/- 2.1 vs. 3.7 +/- 0.87 microg/dL) and remained enhanced to the same extent in AA and FR-AA groups. The tailflick latency prolonged in the AA group was reduced by food restriction.

CONCLUSION

These results show that 40% food restriction associated with elevated CORT levels mitigated the inflammatory parameters activated during AA.

[Antioxidant effects of melatonin]

Increase in knowledge about reactive oxygen species action mechanisms and oxidative stress effects in living organisms led to intensive seeking for new, more effective substances, which prevent extreme development of oxidative stress or are able to decrease its negative influence, damaging cell structures and many cell functions. These substances are called antioxidants, scavengers, trappers or quenchers. In nineties, melatonin became the centre of the interest in the filed of investigation of antioxidative properties of different chemical substances. This is in living organisms ubiquitous substance with relatively simple chemical structure, good physical properties and wide physiological effects. The main role of endogenous melatonin comprises receptor-mediated biological rhythms synchronisation. Among other functions mentioned later belong anti-gonadotropic, immunotropic and non-receptor-mediated antioxidative effects. Melatonin is said to have also antineoplastic properties. Its anti-aging effect is discutable.

Impact of enteral feeding on gastric tonometry in healthy volunteers and critically ill patients

BACKGROUND

Enteral feeding may interfere with gastric tonometry measurement. The effect of enteral nutrition on gastric tonometry has not been fully documented.

METHODS

Seven healthy volunteers and nine stable intensive care unit (ICU) patients with poor tolerance of gastric feeding were investigated. Consecutive continuous postpyloric and gastric feeding, both at two different rates (40 and 100 ml. h-1, respectively), and an intragastric 200 ml nutrition bolus were studied. Gastric intramucosal PCO2 (PiCO2) was measured by air tonometry and in patients a gastric intramucosal-arterial PCO2 difference (PCO2 gap) was calculated. Hemodynamics and blood gases were also measured.

RESULTS

In volunteers, PiCO2 remained stable during the postpyloric phase. During continuous gastric feeding PiCO2 did not change significantly, although in 4 volunteers PiCO2 increased >0.5 kPa. PiCO2 decreased significantly after gastric bolus from 6.9+/-0.4 to 6.1+/-0.5 kPa (P<0.05). Eight patients had an increased PCO2 gap (>1 kPa) at baseline (1.8+/-0.6 kPa). PCO2 gap changes during the whole study were not statistically significant. However, during the postpyloric phase (or immediately afterwards), the PCO2 gap increased by more than 0.5 kPa in 5 patients. After gastric bolus, a decrease in PCO2 gap >0.5 kPa was seen in 5 patients.

CONCLUSION

In volunteers, postpyloric feeding does not interfere with gastric tonometry measurement and gastric bolus leads to a PiCO2 decrease. The impact of postpyloric and gastric feeding on gastric tonometry in ICU patients with compromised gut is variable.

Comparison of microsurgical suture with fibrin glue connection of the sciatic nerve in rabbits

The regeneration of the sciatic nerve after microsuture was compared with the connection of transected nerve with a coagulum of autologous blood plasma in 20 rabbits. The epineuroperineural suture was performed in 10 rabbits (group A). The severed nerve was approximated with fibrin glue of autologous blood plasma in 10 rabbits (group B). Their skin sensation margin during a 3-month-period of regeneration was examined, 90 days after surgery the connection was inspected and the nerve conduction velocity was measured across the site of the anastomosis. The microsuture was found to be firm in all 10 animals of group A. On the other hand, in 2 animals of group B, the glue failed to keep the nerve stumps approximated (dehiscence occurred in 20% of the animals). There were no significant differences found on clinical and electrophysiological testing of regenerated nerves of both groups. The method of autologous fibrin glue in the repair of peripheral nerve transection does not provide a sufficiently firm connection. This procedure with the preparation of the centrifuged plasma is a more time-consuming method in comparison with the microsuture. Epineuroperineural microsuture with maximal effort to adapt the corresponding nerve fibres remains the method of choice for peripheral nerve reconstruction.

Suppression of adjuvant arthritis in rats by boar seminal immunosuppressive fraction

OBJECTIVE

The effect of the immunosuppressive fraction of boar seminal vesicle fluid (ISF) was tested on the manifestation of adjuvant arthritis (AA) in rats.

METHODS

The inhibitory effect of ISF on mitogen-stimulated proliferation of rat lymphocytes was evaluated by immunoassay using bromodeoxyuridine incorporation. Adjuvant arthritis was induced in male Long Evans rats with Mycobacterium butyricum in adjuvant. ISF was administered at the time of the induction of arthritis. At the time of maximal manifestation of the disease, the hind paw swelling and thymus weight were estimated. IgM and IgG in the rat blood sera were quantified by sandwich ELISA. Serum corticosterone was analyzed by radioimmunoassay. Serum NO2-/NO3-were estimated by diazotation. Serum albumin was measured spectrophotometrically. The expression of IL-6 mRNA in peritoneal macrophages was estimated by dot-blot hybridization.

RESULTS

Treatment of arthritic rats with ISF attenuated hind paw edema. The production of IgG subclasses dropped in ISF-treated AA rats. The thymus mass and serum albumin concentration were partially restored due to the ISF treatment. Serum corticosterone as well as NO2-/NO3- concentrations were reduced by the ISF effect. The expression of IL-6 in peritoneal macrophages was inhibited in AA rats after ISF treatment.

CONCLUSION

ISF attenuated the manifestation of AA in rats and mitigated the inflammation. Immunoglobulin production was most probably inhibited by the decreased proliferation of B lymphocytes.

Dorsal rhizotomy changes the spontaneous neuronal activity of nuclei in the medial thalamus

The aim of this study was to examine the influence of unilateral dorsal root section at the cervicothoracic level of the spinal cord on the spontaneous neuronal activity of medial thalamic nuclei in the rat. Single unit extracellular recordings from thalamic nuclei, nc. parafascicularis and nc. centralis lateralis, were obtained with glass micropipettes. The abnormal bursting activity of these nuclei following deafferentation was registered, although a correlation between the occurrence of this activity and the degree of autotomy behavior was not found. Such bursts were never observed in the studied thalamic nuclei of control rats.

Anticipation of acute stress in isoprenaline-sensitive and - resistant rats: strain and gender differences

The effect of stress anticipation was studied in two inbred Wistar rat strains with high and low sensitivity to isoprenaline. The animals were exposed to tail-flick and 4-hr water immersion restraint stress on two consecutive days. On the first day stress was applied to one group and the next day to the anticipation group. The changes in adrenal, heart and spleen weights, tail-flick latency, incidence of gastric ulcers, and the antioxidant defense system in the sensorimotor cortex were compared with two non-stressed control groups. Anticipatory stress decreased adrenal weights. The content of thiobarbituric acid reactive substances (TBARS) was increased both in acute and anticipatory stress; superoxide dismutase, glutathione peroxidase, and antioxidative capacity were increased in anticipatory stress only. Stress anticipation decreased the pain threshold in the isoprenaline-sensitive and increased in the isoprenaline-resistant rats and led to more frequent gastric ulcers in the isoprenaline-resistant group. Significant sex differences were observed both in adrenal weights and TBARS content. The relative adrenal weights were negatively correlated with the TBARS content. We suggest that the outcome of anticipatory stress may depend upon the relation between the hormonal and antioxidant functions of the adrenals and that anticipation-induced activation of antioxidant enzymes may ameliorate the acute stress response. Anticipation itself was found to be a stronger stressor than physical acute stress.

Effect of unilateral deafferentation on extracellular potassium concentration levels in rat thalamic nuclei

The autotomy performed by rats after unilateral section of the dorsal roots corresponding to the brachial plexus was frequently attributed to an abnormal painful sensation felt in the peripheral deafferented area. We studied the values of potassium (K(+)) extracellular concentration ([K(+)](e)) in thalamic nuclei of somatic projection in this animal model of deafferentation pain. Potassium concentrations were measured with microelectrodes sensitive to K(+) (K(+)-ISM). When such microelectrodes are gradually inserted into the thalamus, a sudden transient increase of K(+) concentration appears after each step lasting for about 30s. This is followed by a stabilization of K(+) values, which is present for several hours. We measured this stable concentration of K(+) (resting [K(+)](e)) for 3-5 min in different nuclei of the somatic projection to the lateral thalamus of controls and deafferented groups of adult rats under Equithesin anaesthesia. The following thalamic nuclei were explored: the ventral posterior medial and lateral (VPM and VPL) and the adjacent posterior oral (PO) as well as the lateral dorsal (LD) and posterior (LP) and ventral anterolateral (VAL). In the control group (12 rats), the mean values of resting [K(+)](e) expressed in mmol/l in these nuclei were between 3.26 and 3.62. All these values of the K(+) concentration were significantly higher than those in the cerebrospinal fluid for P<0.001. In the deafferented group (21 rats), a significant increase of the resting [K(+)](e) concentration was found in three nuclei only (VPL, VPM, PO) of the thalamus contralateral to the root section, when compared to the corresponding nuclei in the controls. No changes were observed in the other contralateral nuclei and in all nuclei of the thalamus ipsilateral to the deafferentation. The most statistically significant changes in mean values were found in five deafferented animals, which had recently performed autotomy. Localised variations of resting [K(+)](e) observed in each of VPL, VPM and PO nuclei were also demonstrated by curves traced for each control and deafferented animal. The greatest changes in resting [K(+)](e) were observed in the three nuclei mentioned above, where the value of [K(+)](e) attained 6 to 7 mmol/l in deafferented animals. The maximum amplitude peaks of resting [K(+)](e) were found in animals which had recently exhibited autotomy. These enhanced resting values of [K(+)](e) apparently reflect increased activity in the somatic lateral thalamus of deafferented animals. Their possible role in pain and autotomy are discussed.

Suppression of adjuvant arthritis in rats with chronic bromocriptine treatment does not prevent associated oxidative stress

We studied the effect of prolactin (PRL) inhibition by bromocriptine (BRC) in the first phase of adjuvant induced arthritis (AA), up to day 11(BRCl-AA), and in the whole time course of AA, up to day 23 (BRC-AA), on the development of the disease in male Lewis rats. On day 24, arthritic rats showed inhibition of PRL secretion, but not PRL mRNA expression in adenopituitaries. BRC treatment suppressed PRL serum levels and PRL mRNA expression in adenopituitaries. In BRC/-AA group PRL levels and PRLmRNA were at the level of rats with AA. Serum corticosterone (CORT) was stimulated by AA from 16.9+/-5.8 to 59.1+/-8.7 ngml(-1), p<0.05, to the same level in BRC-control (BRC-C) and BRC-AA group and further potentiated in BRCI-AA group (148.2+/-33.1 ngml(-1), p<0.05 vs. group with AA). Hind paw swelling was reduced but not completely inhibited in BRC1-AA group and totally prevented in BRC-AA rats as was the core temperature (36.5+/-0.1 degrees C vs. 37.4+/-.0.1 degrees C in AA rats on day 23, p<0.01). Serum concentration of NO-ZNO-3 rose in rats with AA to 28.7+/-2.5 &mgr;mo1L-1 against. 13.9+/-1.9 &mgr;molL(-1) in controls (p<0.01), remained elevated in BRC-AA group and was potentiated in BRC1-AA group (48.2+/-3.5 &mgr;mol(-1), p<0.01 vs. AA or BRC1-AA group) Thiobarbituric acid reactive substances (TBARS) and antioxidant capacity in the spleen were enhanced in rats with AA and to the same extent in BRC-AA or BRC1-AA groups. These results show a discrepancy between the suppression of clinical symptoms and persisting oxidative stress in AA rats after the BRC induced PRL inhibition. The potentiation of nintric oxide (NO-) production after the sudden cessation of PRL inhibition during the disease may promote further joint damage.

The influence of repeated prestressors on single stress response in rats

The effect of various stressors of different intensity applied in random order before the final single immersion restraint stress was tested in two inbred rat strains, isoprenaline-sensitive and isoprenaline-resistant. The isoprenaline-sensitive strain revealed higher incidence of heart lesions after this single acute stress and low incidence of gastric lesions. The isoprenaline-resistant strain had the opposite characteristics. These differences were constantly reproducible when this strong stressor was used. After prestress by different stressors (tail-flick, ether anaesthesia, Porsolt swimming stress) at different time schedules, the incidence of gastric ulcer lesions, the weight of organs (heart, adrenals, spleen) changed substantially in isoprenaline-sensitive rats only. The most important result was reversal of the extent of gastric lesions. The isoprenaline-sensitive strain revealed more lesions than the isoprenaline-resistant one. The repeated different prestressors mainly changed the reactivity of animals, isoprenaline-sensitive rats becoming more similar to isoprenaline-resistant rats. These findings urged us to interpret carefully the results obtained in stress research with different and multiple stressors both in animals and humans.

Reciprocal connections between the red nucleus and the trigeminal nuclei: a retrograde and anterograde tracing study

An anterograde biocytin and a retrograde WGA-colloidal gold study in the rat can provide information about reciprocal communication pathways between the red nucleus and the trigeminal sensory complex. No terminals were found within the trigeminal motor nucleus, in contrast with the facial motor nucleus. A dense terminal field was observed in the parvicellular reticular formation ventrally to the trigeminal motor nucleus. The parvicellular area may be important for the control of jaw movements by rubrotrigeminal inputs. On the other hand, the contralateral rostral parvicellular part of the red nucleus receives terminals from the same zone in the rostral part of the trigeminal sensory complex, where retrogradely labelled neurones were found after tracer injections into the red nucleus. Such relationships could be part of a control loop for somatosensory information from the orofacial area.

[Acute respiratory distress syndrome]

Acute respiratory distress syndrome (ARDS) is the general term used for severe acute respiratory failure of diverse aetiology. It is associated with a high morbidity, mortality (50-70%), and financial costs. Regardless of aetiology, the basic pathogenesis of ARDS is a systemic inflammatory response leading to a diffuse inflammatory process that involves both lungs, thus causing diffuse alveolar and endothelial damage with increased pulmonary capillary permeability and excessive extravascular lung water accumulation. ARDS is commonly associated with sepsis and multiple organ failure. The clinical picture involves progressive hypoxaemia, radiographic evidence of pulmonary oedema, decreased lung compliance and pulmonary hypertension. Despite the scientific and technological progress in critical care medicine, there is no specific ARDS therapy available at the moment and its management remains supportive. Therapeutic goals include resolution of underlying conditions, maintenance of acceptable gas exchange and tissue oxygenation and prevention of iatrogenic lung injury. Many new specific therapeutic strategies have been developed, however, most of them require further scientific evaluation. The paper reviews definition, basic pathogenesis and pathophysiology of ARDS and discusses current concepts of therapeutic possibilities of ARDS.

Adjuvant arthritis in the rat is associated with decreased binding of nuclear receptors to thyroid hormone responsive element in spleen extracts

In vertebrates, thyroid hormone and its cognate nuclear receptors are involved in a complex arrangement of physiological and developmental function. Since thyroid hormone has also been shown to affect immune responses, we investigated the DNA binding status of T3 receptors of spleen nuclear extracts in a) rats with adjuvant arthritis (AA); b) adrenalectomized rats (ADX), and c) animals with adjuvant arthritis followed by adrenalectomy (AA + ADX). A marked diminution in the functional binding of nuclear thyroid hormone receptors to DR4 thyroid hormone responsive DNA element was found in the spleens of AA and AA + ADX rats when compared to a control group or ADX rats. The data based on in vivo experiments suggest that the nuclear receptor--thyroid hormone responsive element complex status within the cell nucleus may be altered in adjuvant arthritis.

Reciprocal interactions between intralaminar and lateral thalamic nuclei in rats

Reciprocal interactions between intralaminar thalamic nuclei (ncl. centralis lateralis, CL, and ncl. parafascicularis, Pf), the pretectal area (Pt) and lateral thalamic nuclei (ventrobasal complex, VB, ncl. anterior ventralis, AV, and ncl. ventralis anterior, VA) have been observed in ketamine-anaesthetized rats. Extracellular single unit activity has been recorded after single electrical stimuli. Electrical stimulation of the VB evoked a short latency orthodromic response followed by a pause in spontaneous activity in neurones of medial thalamic nuclei. Lateral thalamic neurones responded to electrical stimulation of the intralaminar nuclei or the pretectal area with the same pattern of response. Striatal, sensorimotor cortical or peripheral electrical stimulation also evoked similar responses. The pauses in spontaneous activity were shown to be the result of inhibition since the responsiveness of the intralaminar nuclei or the lateral thalamic neurones to all inputs was abolished or reduced after a conditioning electrical single-shock stimulation in the VB or in the intralaminar nuclei, respectively. The two components of the response were of a different origin, since most of the short latency responses disappeared after medullary, upper cervical sections or large decortications, while the inhibitions persisted. These inhibitions were shown to be of thalamic origin since their duration was decreased after extensive decortications increased after medullary section. It is concluded that the neuroneal properties studied in this report are probably broadly represented throughout the thalamus and that thalamic neurones are under inhibitory control elicited by afferent volleys. This inhibitory control includes a relay in the nucleus reticularis thalami (nRT). The mechanisms of sensory interaction can be purely thalamic, but they can be modulated by suprathalamic and/or mesencephalic loops.

Abnormal neuroneal activities in intralaminar thalamic nuclei following chronic lesions of nucleus reticularis thalami in rats

Extracellular single unit activity in the intralaminar thalamic nuclei (ncl. centralis lateralis, CL, n = 77 and ncl. parafascicularis, Pf, n = 163) and in the pretectal area (Pt, n = 75) was examined following chronic electrolytic lesions of the nucleus reticularis thalami (nRT) in ketamine-anaesthetized rats after single electrical stimuli to the ventrobasal complex (VB). Extensive alterations of either the ongoing ("spontaneous") activity or the pattern of VB evoked responses were observed. Four major changes were observed in the activity of these intralaminar or pretectal neurones: 1) many neurones were silent, two times more frequently than in a parallel study with control intact rats; 2) the firing pattern of all the other neurones was in the form of tonic (stationary-like) discharge, without burst discharges as previously described in intact animals. They were ranked into classes according to their spontaneous discharge: class I, silent (no resting discharge) 12%, class II (1-15 Hz), 54 % and class III (> 16 Hz), 34%. Class III neurones were never found in intact rats; 3) electrical stimulation of the VB evoked a short latency orthodromic excitatory response in these neurones but this response was not followed by any slowing or depression of the spontaneous activity in more than 40% of recorded cells. When it occurred, this pause was shorter than that always observed in intact rats by more than 35% and longer in 7% of the responsive cells. All these changes were correlated with the extent of damage to the ipsilateral nRT; 4) VB stimulation evoked prolonged excitatory responses lasting more than 150 ms in 13% of the responsive cells, and nRT stimulation led to a short latency response followed by a pause of activity. These findings suggest that the nRT is involved in sensory integration and modulation.

Effect of glycosylated and non-glycosylated prolactin on the proliferation of normal human lymphocytes

We evaluated the effects of 2.5x10(-10) M or 5x10(-10) M concentrations of human pituitary prolactin (pPRL), human recombinant non-glycosylated (NG-PRL) and glycosylated (GL-PRL) prolactin on the proliferation of normal human lymphocytes with or without coactivation by interleukin-2 (IL-2). None of the PRL forms alone affected the lymphocyte proliferation in a serum-free medium, however, the stimulatory activity of IL-2 was significantly potentiated with all 3 PRL variants. Since the 5x10(-10) M concentrations of individual PRLs exerted the same effects, this result suggests that GL-PRL in primary lymphocyte culture is not a less mitogenic form, if sufficient amounts of IL-2 are available.

Continuous venovenous hemodiafiltration (CVVHDF) with citrate anticoagulation in the treatment of a patient with acute renal failure, hypercalcemia, and thrombocytopenia

A 72-year-old patient with multiple myeloma was admitted to the intensive care unit because of hypercalcemic crisis and acute renal failure. After 7 days of comprehensive therapy including diuretics steroids, calcitonin, and intermittent hemodialysis (IHD) with low-calcium dialysate, calcium still reached high levels between IHD treatments and thrombocytopenia developed after chemotherapy. CVVHDF with calcium-free bicarbonate dialysate was started. Anticoagulation with 2.2% citrate was performed in order to chelate calcium, and thus treat the hypercalcemia, and to provide regional anticoagulation, and thus reduce the risk of bleeding due to thrombocytopenia. CVVHDF with citrate anticoagulation was continued for 6 days, and standard heparin anticoagulation was started when the hypercalcemia and thrombocytopenia abated.

Potentiation of fentanyl suppression of the jaw-opening reflex by transcranial electrical stimulation

Stinus et al. [L. Stinus, M. Auriacombe, J. Tignol, A. Limoge, M. Le Moal, Transcranial electrical stimulation with high frequency intermittent current (Limoge's) potentiates opiate-induced analgesia: blind studies, Pain, 42 (1990) 351-363.] observed that transcranial electrical stimulation (TCES) with high-frequency intermittent current potentiated opiate-induced analgesia using the tail-flick test. In unanesthetized, chronic preparations, electrical stimulation (0.5 Hz) of the lower incisor pulp of rats elicits a short-(6 ms) and a long-latency (12-18 ms) jaw-opening reflex (JOR) without any evidence of aversive behavior [J. Azerad, F. Fuentes, I. Lendais, A. Limoge, B. Pollin, Methods for selective tooth pulp stimulation in acute and chronic preparations in rats, J. Physiol., 406 (1988) 3P.]. Fentanyl increases thresholds of both reflexes and transiently suppresses the long-latency JOR. We then decided to look at the influence of TCES on both drug-induced mean of maximal threshold variation (MMTV) and duration of JOR suppression period. These parameters have been investigated in 43 Wistar rats with or without TCES administered for 3 h before the drug injection and throughout the testing period. TCES alone has no effect. In contrast, it significantly increases the duration of the reflex suppression period (149 +/- 5% vs. control, P < 0.001) while fentanyl-increased reflex thresholds remain unchanged. The fentanyl-induced JOR suppression period returns to the control values 2 days later. When a second 3-h TCES session is delivered 2 or 4 days after the first TCES session, a similar increase of this suppression period is observed. Moreover, 2 days after a second TCES session, an increase of the duration of the fentanyl-induced JOR suppression period is systematically observed. In contrast, a 6-h TCES session never induces such effects. These results confirm a potentiating effect of TCES on opioid action and demonstrate the value of repeated TCES sessions.

[Free radicals in the central nervous system]

Central nervous system has a low antioxidative capacity, which is formed mainly by ascorbic acid. Therefore the cerebral tissue is threatened by the increased formation of free radicals and their metabolites (ROS--reactive oxygen species). ROS are formed such as in reperfusion phase after ischemia and in catecholamine metabolism, in oxidative stress due to hyperglycaemia. Polyunsaturated fatty acids (PUFA) are peroxidased by ROS; proteins and DNK are damaged as well. Free radicals are involved in etiology and pathogenesis of many CNS diseases, such as neuritis, Alzheimer disease, Parkinson disease, Huntington disease, aging and atherosclerosis of the brain, epilepsy, etc. During the antioxidant therapy it is necessary to consider the types of ROS, their origin and their mode of action, whether to administer hydrophilic or lipophilic antioxidants, eventually chelate agents, etc. Hydrophylic antioxidants are acting very soon after the administration, whereas the lipophilic ones reach their target tissues with a great delay. Therefore it is better to apply them preferentially like a prevention, if possible. Enzymatic antioxidants (SOD, GSPHx and catalase and others) are usually acting only for a short time. The methods of estimation of free radicals attacks are discussed as well their possible pathophysiological effects.

[Microsurgical Technique in Injuries of Pheripheral Nerves Part II: Experimental Study (Comparison of Microsuture with the Technique of Gluing by Means of Plasma Coagulum of the Ischiadic Nerve).]

In a group of 20 rabbits the authors compared regeneration of the nervus ischiadicus after microsuture and after gluing the severed nerve with plasma coagulum. In 10 rabbits of group A epineural suture was performed, in 10 rabbits of group B the severed nerve was glued with autologous plasma coagulum. During a three-month regeneration period the authors examined the threshold of sensation 90 days after surgery the anastomosis was examined and also the rate of conduction across the anastomosis. Firmness of the suture was proved in 100% (group A), in two glued nerves dehiscence of the anastomosis occurred, the coagulum was found to be firm in 80 % (group B). When the repaired nerves of both groups were examined, no significant difference was found during clinical examination nor in the conduction across the anastomosis. The method of gluing the nerve with plasma coagulum does not ensure sufficient firmness of the anastomosis on traction. As compared with suture, gluing and preparation of centrifuged plasma is a more tedious method. The method of choice for joining a nerve on the extremities remains microsuture with maximal efforts to achieve adaptation of the corresponding nerve fascicles. Key words: rabbit, nervus ischiadicus, regeneration, microsuture, fibrin coagulum.