[Development and Periodicity of Human Exposures in Suicidal Intention Reported to the Centre Erfurt from 2004-2013]

Aim of the Study: Exposures in suicide attempts are demanding for hospitals and poisons information centres (PICs). Therefore, the time characteristics of their frequency were studied. Methods: A retrospective analysis was undertaken of all human exposures reported to Centre Erfurt from the beginning of 2004 to the end of 2013 according to their frequency in the respective year, season, month, weekday, time of the weekday, circumstances of exposure, age and gender. Results: 59.7% of all exposures (n=137 104) were accidental, 23.4% occurred in suicide attempts and 3.3% in substance abuse. 0.3% of the suicide attempts resulted in death. Their number continuously increased from n=2 422 in 2004 to n=3 458 in 2013, but their relative frequency remained almost constant at 23.4%. Their highest numbers were reached in the spring and summer with maxima in July and August and minima in February and September. During the week, the most suicide attempts were observed between Sunday and Tuesday and the least on Friday. Highest rate of suicide attempts was seen at 10 pm and lowest at 6 am. The median of age was 39 years (first quartile 24 years, third quartile 50 years). The female proportion was almost twice as high as the male. Conclusions: Hospitals the Centre Erfurt is serving should be particularly prepared for exposures in suicide attempts in the spring and summer (especially in July and August), at the beginning of the week and shortly before midnight.

[Human Single Drug Exposures to Non-opioid Analgesics Reported to the Poisons Information Centre Erfurt from 2003 to 2012]

AIM OF THE STUDY

Because of their frequency, non-opioid analgesics (NOA) single drug exposures registered by Poisons Information Centre (PIC) Erfurt have been studied over a decade.

METHODS

A retrospective analysis of frequencies, circumstances of exposure, symptom severity, and age groups in NOA single drug exposures received by the PIC Erfurt from the beginning of 2003 to the end of 2012 was undertaken.

RESULTS

Of all 4749 NOA single drug exposures, the 10 most frequent were caused by paracetamol (n=1 686), ibuprofen (n=1 439), acetylsalicylic acid (n=456), dipyrone (n=274), diclofenac (n=267), flupirtine (n=138), naproxen (n=41), etoricoxib (n=36), indomethacin (n=24), and dexketoprofen (n=19). Paracetamol single drug exposures increased from 158 in 2003 to 216 in 2007 and fell afterwards to 133 in 2012. Ibuprofen single drug exposures continously rose from 57 in 2003 to 258 in 2012. Adults were more often involved in NOA (53.8%) and all single drug exposures (54.1%) than children (45.9% and 45.6%, respectively). Suicidal attempts were more frequent in NOA (43.1%) than in all single drug exposures (34.2%), whereas accidental exposures or exposures in abuse were less often (33.4 and 0.2%, 46.0 and 0.9% respectively). NOA single drug exposures resulted mostly in none to minor symptoms (77.0%) and rarely in moderate (2.1%) or severe symptoms (1.0%). One adult was found dead after probable ingestion of 32 g of acetylsalicylic acid in suicidal intention.

CONCLUSIONS

Because many NOA are over-the-counter drugs, it is difficult to obtain data on their use. PIC data could provide information on the NOA use in the population.

[Poisonings due to Substance Abuse Reported to the Poisons Information Centre Erfurt from 2002 to 2011]

AIM OF THE STUDY

Because of their importance for clinical toxicology, developments of sub-stance abuse reported to the Poisons Information Centre (PIC) Erfurt were investigated and compared to other reasons of human exposures.

METHODS

A retrospective analysis of all human exposures (exposures of humans to substances in abuse, accidental and unknown circumstances, and suicide attempts) (n=125,130) from the beginning of 2002 to the end of 2011 was undertaken according to substance classes, reasons of exposures, symptom severity, age groups, and gender.

RESULTS

Cases of substance abuse (3,760, 3.0% of all exposures) continuously increased from 252 (92 with one and 160 with multiple substances) in 2002 to 507 in 2011 (239 with one and 268 with multiple substances). In relation to all exposures, only the abuse of multiple substances rose significantly (p<0.001). In comparison to all substances of exposure, ethanol, amphetamine-type stimulants, benzodiazepines/analogues, and liquid ecstasy abuse significantly (p<0.005) increased while cannabis and Brugmansia/Datura species abuse significantly (p<0.05) decreased. Substance abuse significantly (p<0.001) more often caused moderate (23.7%) and severe symptoms (6.1%) than in suicide attempts (9.6%; 4.4%). First legal highs exposures were registered in 2010 and led significantly (p<0.001) more often to moderate symptoms (50%) than cannabis exposures (19.4%).

CONCLUSIONS

The clinical significance of substance abuse is shown by the fact that it resulted more often in moderate and severe symptoms than suicide attempts. Data on substance abuse from PICs could supplement official annual drug reports in aspects of clinical toxicology.

Acute Cerebrovascular Disease in the Young

Background and Purpose—

Strokes have especially devastating implications if they occur early in life; however, only limited information exists on the characteristics of acute cerebrovascular disease in young adults. Although risk factors and manifestation of atherosclerosis are commonly associated with stroke in the elderly, recent data suggests different causes for stroke in the young. We initiated the prospective, multinational European study Stroke in Young Fabry Patients (sifap) to characterize a cohort of young stroke patients.

Methods—

Overall, 5023 patients aged 18 to 55 years with the diagnosis of ischemic stroke (3396), hemorrhagic stroke (271), transient ischemic attack (1071) were enrolled in 15 European countries and 47 centers between April 2007 and January 2010 undergoing a detailed, standardized, clinical, laboratory, and radiological protocol.

Results—

Median age in the overall cohort was 46 years. Definite Fabry disease was diagnosed in 0.5% (95% confidence interval, 0.4%–0.8%; n=27) of all patients; and probable Fabry disease in additional 18 patients. Males dominated the study population (2962/59%) whereas females outnumbered men (65.3%) among the youngest patients (18–24 years). About 80.5% of the patients had a first stroke. Silent infarcts on magnetic resonance imaging were seen in 20% of patients with a first-ever stroke, and in 11.4% of patients with transient ischemic attack and no history of a previous cerebrovascular event. The most common causes of ischemic stroke were large artery atherosclerosis (18.6%) and dissection (9.9%).

Conclusions—

Definite Fabry disease occurs in 0.5% and probable Fabry disease in further 0.4% of young stroke patients. Silent infarcts, white matter intensities, and classical risk factors were highly prevalent, emphasizing the need for new early preventive strategies.

Clinical Trial Registration Information—

URL: http://www.clinicaltrials.gov .Unique identifier: NCT00414583

Calcium channel antagonist exposures reported to the Poisons Information Center Erfurt

BACKGROUND

We investigated the toxicity profile of the three main groups of calcium channel antagonists (CCA) and compared mixed CCA exposures (CCA plus another drug) with mono CCA exposures.

METHODS

All CCA exposures reported to the PIC Erfurt from 2000 to 2009 were analyzed retrospectively.

RESULTS

In total, 727 (230 mono and 497 mixed) CCA exposures were registered. Although CCA exposures increased almost twofold from 56 in 2000 to 108 in 2009 their relative frequency to all exposures remained constant. The five CCAs most frequently involved in exposures were the five most frequently prescribed ones in Germany over the same period. In mono and mixed CCA exposures, none or minor symptoms were most often seen with dihydropyridines (mono: 84.7%; mixed: 68.0%) followed by diltiazem (mono: 71.4%; mixed: 62.5%) and verapamil (mono: 57.1%; mixed: 50.0%). Highest rates of moderate (mono: 8.6%: mixed: 20.2%) and severe symptoms (mono: 18.6%; mixed: 23.7%) were observed after verapamil ingestions. Death most frequently occurred with diltiazem (mono: 28.6%; mixed: 12.5%). Rates of moderate symptoms were higher in mixed (13.3%) than in mono CCA exposures (4.8%). No distinct differences were seen regarding the relative frequency of none or minor symptoms, severe symptoms, and death between mono and mixed CCA exposures.

CONCLUSION

Exposures to verapamil more often resulted in moderate and severe symptoms than with dihydropyridines. Death mainly occurred with diltiazem. Moderate symptoms were more frequent in mixed than in mono CCA exposures. The frequency of CCAs involved in exposure was related to their prescription.

Combined thrombolysis with abciximab and rtPA in patients with middle cerebral artery occlusion

BACKGROUND

In patients with acute middle cerebral artery (MCA) occlusion, recanalization rates with intravenous (IV) recombinant tissue plasminogen activator (rtPA) are limited. Aim- We evaluated the feasibility and safety of combined IV thrombolysis with abciximab and reduced dose rtPA in a 3- to 6-h time window.

METHODS

We prospectively (March 2002 to February 2005) studied patients with symptomatic MCA occlusion on computed tomography (CT) angiography and absence of major early ischemic changes (EIC) on non-contrast CT (NCCT) within 3-6 h from symptom onset. Patients were treated with IV abciximab and half-standard dose rtPA. Outcome parameters were symptomatic intracerebral hemorrhage (sICH), early clinical improvement and functional independence at discharge (modified Rankin Scale score < or = 2).

RESULTS

Of 13 patients, mean age was 62 +/- 11 years, onset-to-treatment time 4.8 +/- 0.9 h and median baseline National Institutes of Health Stroke Scale score 11 (interquartile range 6.5-13.5). sICH occurred in one patient (8%). We observed early clinical improvement in four patients (31%). Six patients (46%) were functionally independent at discharge.

CONCLUSIONS

In patients with acute symptomatic MCA occlusion and absence of major EIC on NCCT, combined IV thrombolysis with abciximab and half-standard dose rtPA was feasible and seemed to be safe if applied within 3-6 h from symptom onset.

[Percutaneous nephrolithotomy - always effective and free of complications?]

PURPOSE

The purpose of this study was to evaluate the results and complications of percutaneous nephrolithotomies performed within 5 years in our patients.

MATERIALS AND METHODS

From 2001 to 2005 in our department 158 percutaneous nephrolithotomies (PNL) in 131 patients and 138 renal units were performed. The indications for PNL were calculus greater than 2 cm, failed ESWL, and when there is additional urinary obstruction which was not caused by the stone itself. Data concerning past medical history, about the procedure including complications and the postoperative course were collected and evaluated.

RESULTS

87 (63 %) of the patients had a history of prior stones. The main symptoms were flank pain, recurrent renal colic and urinary tract infection. The stones treated had a size from 5 to 60 mm. In 40 patients (29 %) relief of urinary obstruction (double-J-ureteral stent or percutaneous nephrostomy) or ESWL was performed prior to PNL. Mean operating time was 83 (30 - 235) minutes including retrograde placement of a ureteral catheter and nephrostomy. Complications occurred in 26 (16.5 %) procedures. Severe complications were: one fatal pulmonary embolism, one septicaemia, three open revisions (including one nephrectomy) and four blood transfusions for blood loss. In 94 patients (68 %) there was no residual stone or gravel after the first PNL. No further therapy was necessary in 17 (39 %) of the 44 patients with incomplete stone removal. 19 patients underwent a secondary PNL. In these procedures the efficacy decreased. 102 of 131 patients (138 renal units = 73.9 %) were discharged without residual stone after 158 procedures.

CONCLUSIONS

PNL is an efficient and rarely complicated procedure for larger stones of the upper urinary tract. Even so, the occurrence of severe complications must be considered. Complications can be minimised by the use of a standardised therapeutic pathway.

Renal morphology of the euryhaline flounder (Platichthys flesus): distribution of arginine vasotocin receptor

The current study characterized tubular segmentation of the European flounder nephron and localized the vasotocin receptor expression by immunohistochemistry. Flounder nephron was shown to comprise a prominent renal corpuscle, short neck segment, proximal tubule I, proximal tubule II, collecting tubule, and collecting duct. Using specific antibodies raised against flounder vasotocin receptor, specific V(1) receptor staining was detected within the glomeruli, the endothelial surface of the afferent and efferent arterioles, and the capillaries surrounding the collecting duct system. Immunostaining for the receptor was exclusively vascular and there did not appear to be a tubular component.

[Lyme disease--a reason for sudden sensorineural hearing loss and vestibular neuronitis?]

BACKGROUND

Lyme disease has been described as one possible cause of sudden sensorineural hearing loss and vestibular neuronitis. The necessity of serological diagnosis and its therapeutic consequences have been discussed controversially.

PATIENTS AND METHODS

344 patients with acute sensorineural hearing loss and 66 patients with vestibular neuronitis were examined in retrospect. By means of ELISA (Enzygnost Borreliosis, Dade Behring Marburg) the specific prevalences of IgG- and IgM-antibodies against borrelia in serum were evaluated. The frequency of seroprevalences for both diseases were compared to those given in the literature. Neurootological findings of the seropositive patients were compared with those of seronegative and analysed statistically.

RESULTS

15.7 % of the patients with sudden sensorineural hearing loss had positive levels of IgG-antibodies. IgM-titers were elevated in 4.7 % of the patients. The seroprevalences for IgM and IgG were above those described by other investigators for the healthy population. Patients with positive IgM-antibodies showed more often low frequency hearing loss than IgG-positive patients. 18.2 % of the patients with neuronitis vestibularis had IgG- and 1.5 % IgM-antibodies against Borrelia. Whereas IgG occurred more often than known for the healthy population, IgM was within the limit for the healthy population. The seropositive group did not show any remarkable neurootological signs compared with the seronegative group.

CONCLUSIONS

Because of the elevated seroprevalences Borrelia infections may be one possible but very rare cause of sudden sensorineural hearing loss and vestibular neuronitis. Low frequency hearing loss may be a sign for an infection with Borrelia as an etiological factor especially in combination with seropositive titers. In case of the presence of IgM-antibodies, patients may be treated with oral antibiotics (Doxycyclin, Cefuroxim). In patients with neuronitis vestibularis a neuroborreliosis should be excluded by means of lumbar puncture.

Characterization of a type IIb sodium-phosphate cotransporter from zebrafish (Danio rerio) kidney

Zebrafish (Danio rerio) express two isoforms of the type IIb Na-dependent P(i) cotransporter (NaPi). Type NaPi-IIb1 has previously been cloned and characterized. Here, we report the cloning of the NaPi-IIb2 transcript from zebrafish kidney, its localization, and its functional characterization. RT-PCR with renal RNA and degenerate NaPi-IIb-specific primers resulted in a specific fragment. 3'-Rapid amplification of cDNA ends yielded a product that contained typical NaPi-IIb characteristics such as a cysteine-rich COOH terminus and a PDZ (PSD95- Dlg-zona occludens-1) binding motif. Several approaches were unsuccessful at cloning the 5' end of the transcript; products lacked an in-frame start codon. The missing information was obtained from an EST (GenBank accession number ). The combined clone displayed a high degree of homology with published type IIb cotransporter sequences. Specific antibodies were raised against a COOH-terminal epitope of both NaPi-IIb1 and NaPi-IIb2 isoforms. Immunohistochemical mapping revealed apical expression of both isoforms in zebrafish renal and intestinal epithelia, as well as in bile ducts. The novel clone was expressed in oocytes, and function was assayed by the two-electrode voltage-clamp technique. The function of the new NaPi-IIb2 clone was found to be significantly different from NaPi-IIb1 despite strong structural similarities. NaPi-IIb2 was found to be strongly voltage sensitive, with higher affinities for both sodium and phosphate than NaPi-IIb1. Also, NaPi-IIb2 was significantly less sensitive to external pH than NaPi-IIb1. The strong structural similarity but divergent function makes these zebrafish transporters ideal models for the molecular mapping of functionally important regions in the type II NaPi-cotransporter family.

Polyvalent cation receptor proteins (CaRs) are salinity sensors in fish

To determine whether calcium polyvalent cation-sensing receptors (CaRs) are salinity sensors in fish, we used a homology-based cloning strategy to isolate a 4.1-kb cDNA encoding a 1,027-aa dogfish shark (Squalus acanthias) kidney CaR. Expression studies in human embryonic kidney cells reveal that shark kidney senses combinations of Ca(2+), Mg(2+), and Na(+) ions at concentrations present in seawater and kidney tubules. Shark kidney is expressed in multiple shark osmoregulatory organs, including specific tubules of the kidney, rectal gland, stomach, intestine, olfactory lamellae, gill, and brain. Reverse transcriptase-PCR amplification using specific primers in two teleost fish, winter flounder (Pleuronectes americanus) and Atlantic salmon (Salmo salar), reveals a similar pattern of CaR tissue expression. Exposure of the lumen of winter flounder urinary bladder to the CaR agonists, Gd(3+) and neomycin, reversibly inhibit volume transport, which is important for euryhaline teleost survival in seawater. Within 24-72 hr after transfer of freshwater-adapted Atlantic salmon to seawater, there are increases in their plasma Ca(2+), Mg(2+), and Na(+) that likely serve as a signal for internal CaRs, i.e., brain, to sense alterations in salinity in the surrounding water. We conclude that CaRs act as salinity sensors in both teleost and elasmobranch fish. Their tissue expression patterns in fish provide insights into CaR functions in terrestrial animals including humans.

Documentation and evaluation of adverse drug reactions (ADR)--contribution from a poison information center

The Department of Clinical Pharmacology in Jena is a pharmacovigilance center in a study on intensified spontaneous adverse drug reaction reporting. Physicians specialized in clinical pharmacology screen admissions to the Department of Internal Medicine for possible adverse drug reactions. Because of the collaboration between the Pharmacology Department and the nearby Poison Information Center (PIC) in Erfurt the question occurred whether the latter might contribute to adverse drug reaction monitoring. We compared the ADR registered by the intensified spontaneous reporting system in 1999 with those of the PIC during the same period. Each symptom observed was regarded as 1 case. Every suspected drug was also treated separately. The symptoms were classified using adverse reaction terminology. The drugs were classified according to the WHO Anatomical Therapeutic Chemical (ATC) classification index. The causality assessment was based upon bibliographic data and the method of Bégaud et al. [1985]. Only possible, probable or very probable ADR were compared. The PIC registered mainly psychiatric and nervous system disorders sedation and extrapyramidal disorders were the most frequent reactions - unlike the pharmacovigilance study which registered primarily gastrointestinal and heart rate disorders. The PIC registered mainly drugs used in the therapy of disorders of the central nervous system, i.e. mostly psycholeptics and drugs acting on the alimentary tract, mostly anticholinergics. Drugs for the therapy of sensory organs disorders were frequent owing to the systemic and local adverse drug effects of anticholinergic mydriatics. The PIC and pharmacovigilance centers can benefit from co-operation. The PIC provides easy access to qualified drug information and is thus a useful tool in ADR evaluation. Although the number of adverse reactions assessed was small, their evaluation revealed problems in drug usage which would not otherwise be reported. The evaluation has enlarged the pool of ADR data which is the basis for signal detection.

Nutmeg (myristicin) poisoning--report on a fatal case and a series of cases recorded by a poison information centre

In literature, cases of nutmeg abuse have been described repeatedly, but only one fatal case of poisoning was reported [1]. In the present case, myristicin (4 microg/ml) was detected for the first time in the postmortal serum of a 55-year-old woman. Identification was achieved with the aid of UV-VIS spectroscopy and TLC; for quantification, HPLC was used. Because also flunitrazepam (0.072 microg/ml) was found, death had probably been due to the combined toxic effect of both substances. From 1996 to 1998, in a series of cases, seven poisonings with nutmeg were recorded by the Erfurt Poison Information Centre. Even where higher doses (20-80 g of powder) had been ingested, a life-threatening situation was never observed. In one of these cases, a myristicin blood level of 2 microg/ml was measured 8h after ingestion of two to three tablespoonful of nutmeg powder (approx. 14-21 g, or 280-420 mg/kg).

Early development of the zebrafish pronephros and analysis of mutations affecting pronephric function

The zebrafish pronephric kidney provides a simplified model of nephron development and epithelial cell differentiation which is amenable to genetic analysis. The pronephros consists of two nephrons with fused glomeruli and paired pronephric tubules and ducts. Nephron formation occurs after the differentiation of the pronephric duct with both the glomeruli and tubules being derived from a nephron primordium. Fluorescent dextran injection experiments demonstrate that vascularization of the zebrafish pronephros and the onset of glomerular filtration occurs between 40 and 48 hpf. We isolated fifteen recessive mutations that affect development of the pronephros. All have visible cysts in place of the pronephric tubule at 2–2.5 days of development. Mutants were grouped in three classes: (1) a group of twelve mutants with defects in body axis curvature and manifesting the most rapid and severe cyst formation involving the glomerulus, tubule and duct, (2) the fleer mutation with distended glomerular capillary loops and cystic tubules, and (3) the mutation pao pao tang with a normal glomerulus and cysts limited to the pronephric tubules. double bubble was analyzed as a representative of mutations that perturb the entire length of the pronephros and body axis curvature. Cyst formation begins in the glomerulus at 40 hpf at the time when glomerular filtration is established suggesting a defect associated with the onset of pronephric function. Basolateral membrane protein targeting in the pronephric duct epithelial cells is also severely affected, suggesting a failure in terminal epithelial cell differentiation and alterations in electrolyte transport. These studies reveal the similarity of normal pronephric development to kidney organogenesis in all vertebrates and allow for a genetic dissection of genes needed to establish the earliest renal function.

The central vessel of the renal countercurrent bundles of two marine elasmobranchs--dogfish (Scyliorhinus caniculus) and skate (Raja erinacea)--as revealed by light and electron microscopy with computer-assisted reconstruction

The renal countercurrent bundles of elasmobranch fish were studied by light and electron microscopy. The kidneys of the lesser spotted dogfish, Scyliorhinus caniculus Blainville, and the little skate, Raja erinacea Mitchill, were investigated. Three-dimensional reconstruction with computer assistance revealed the spatial association of the renal tubular segments and their relationships to each other, as well as to the microvasculature. Regular association between structures was assessed by quantification of contact points on histological sections. The bundles contain a hairpin loop of neck segment and the beginning of the proximal tubule, PIa. The limbs of this loop closely adhere to each other, and a second loop (the early distal tubule) coils around the first loop at the tip of the bundle. The collecting tubule runs between the two loops, and merges with the collecting duct inside the end portion of the bundle. A single lymph capillary-like vessel originates from a few blind-ended rami at the tip of the bundle and runs in close contact with the collecting tubule along the entire bundle. This central vessel merges via several side branches with the venous sinusoid capillaries of the peritubular blood circulation. Thereby the central vessel provides a channel for convective flow of NaCl-rich fluid unidirectionally to the venous portal system of the mesial tissue zone of the kidney. By the close spatial arrangement of the collecting tubule and the central vessel countercurrent exchange of urea from the collecting tubule urine to the fluid in the central vessel is feasible. Thus, the spatial organisation of renal tubular segments and the central vessel is considered to represent the morphological correlate to urea retention by the kidney of Elasmobranchii.

Translated anti-sense product of the Na/phosphate co-transporter (NaPi-II)

The homeostasis of Pi in marine teleosts is maintained by renal Pi secretion as well as by Pi reabsorption. A Na/Pi co-transport system belonging to the NaPi-II protein family is instrumental in tightly controlled renal Pi handling in mammals and fish. We have isolated an NaPi-II related cDNA from winter flounder. It was cloned from a female gonad cDNA library and is 624 bp long. The transcript is expressed in female and male flounder gonads as well as in kidney and intestine, although at very low levels. RNase H digestion experiments revealed an opposite orientation of the transcript with regard to NaPi-II-related mRNA. The anti-sense orientation was confirmed by genomic sequence analysis and Southern blotting. Alluding to the sense transcript, the anti-sense transcript was denoted IPAN. The open reading frame of IPAN encodes a basic protein of 68 amino acid residues. Immunohistochemistry confined the anti-sense related protein, Ipan, to a submembranous compartment of immature oocytes, suggesting a role in oocyte development. In kidney and intestine Ipan is partly co-localized with the Na/Pi co-transporter, implying a regulatory function for the anti-sense protein. However, direct protein-protein interaction could not be established. The existence of a putative open reading frame in other species extends the biological significance of the novel protein.

Na-P(i) cotransport sites in proximal tubule and collecting tubule of winter flounder (Pleuronectes americanus)

Localization of a recently described and cloned Na-Pi cotransport system from flounder was investigated by reverse transcription-polymerase chain reaction (RT-PCR) of microdissected tubules and by immunocytochemistry of kidney of winter flounder. Histological examination showed a small glomerulus, an extremely short proximal tubule PI with a selective affinity to Lens culinaris agglutinin from lentils, and an extensive second proximal tubule segment PII (> 90% of proximal tubules), consisting of cells with numerous apical clear vesicles and extensive amplification of basolateral cell membranes. PII merged with the collecting tubule/ collecting duct (CT/CD) system without a distal segment. By RT-PCR, PII cells revealed high levels of NaPi-II related RNA; low levels were also observed in CTs. Previously characterized antisera against different epitopes of flounder NaPi-II specifically labeled the basolateral regions of PII and the apical cell portion of CT/CD cells and of some PII cells. These results suggest that tubular secretion of P(i) occurs in PII of teleost fish with modulation of urinary P(i) content in the subsequent CT/CD system.

Na-Pi cotransport in flounder: same transport system in kidney and intestine

The cloning of a renal Na-Pi contransport in system from winter flounder (P eudopleuronectes americanus) has recently been reported. We used this information to answer the questions 1) what is the distribution of the transport protein along the nephron? and 2) how are renal and intestinal transporters related? The distribution of the flounder NaPi-II protein was tested using two antisera raised against partial sequences (amino acids 1-14 and 388-441) of the transporter. Antibody-specific fluorescence was detected at the basolateral membrane of epithelial cells in the proximal tubular segment PII. Two clones corresponding to the renal Na-Pi cotransporter were isolated from a flounder intestinal cDNA library. Their functional properties were determined using Xenopus laevis oocytes. The apparent affinities for Pi [Michaelis constant (K(m)) = 0.063 mM] and Na (K(m) = 45.3 mM), as well as the pH dependency (increasing transport activity with increasing pH), showed the same characteristics in both intestinal and the renal systems. Sequence analysis revealed that the two intestinal clones were 100% homologous to the renal cDNA, Flounder NaPi-II-specific immunofluorescence was observed predominantly at the apical membrane on intestinal cross sections. We report the cloning and expression of the first intestinal Na-Pi cotransport system. This transporter belongs to the small group of proteins that exhibit the same function in the apical and the basolateral membranes of different cells.

Quantitative investigations of acetylcholinesterase activities in colorectal malformations

In cases of colorectal innervation disturbance the histological and histochemical findings are well placed to classify the morphological state and to indicate to the pediatric surgeon the therapeutic direction. Any limitation of their value results from technical errors, age dependent localization of morphological structures and the subjectivity of the assessment. For this reason a quantitative biochemical investigation of cholinesterase activity in homogenized investigation of cholinesterase activity in homogenized rectal mucosa specimens and resected bowel segments was performed. The biochemical standard value of the AChE-activity amounts up to 3-6 x 10(-7) mol ACh/min/g in healthy test patients and the ratio of specific/unspecific esterases 1.1 to 1.3. The percentage of AChE to the total enzyme activity was 47.5%. The standard distribution of the different globular and asymmetric cholinesterase structures is described by the proportion of the molecular types G1/G2/G4 and A12. These main types determine the biochemical nature of the human rectum. Hypertrophy of cholinergic nerve fibres in aganglionic bowel segments correlates pathobiochemically with the increase of the cholinesterases caused by the high molecular tetramer G4. However, the Hirschsprung's disease could not be differentiated by the percentage of the AChE-activity to the total ChE-activity because of the continuous increase in the BChE in the aganglionic tissue. Neuronal intestinal dysplasias with their main cholinergic nerve fibre hyperplasias are characterized by disturbances of the dualism and interrelation of different cholinesterases. By means of pathogiochemical investigations the subjective factor in the assessment of histochemical states is avoided and the diagnostic accuracy increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphology and element distribution of magnesium-secreting epithelium: the proximal tubule segment PII of dogfish, Scyliorhinus caniculus (L.)

Proximal tubule segment PII cells of marine elasmobranch fish were studied by transmission electron microscopy of thin sections, and X-ray microanalysis was performed with freeze-dried cryosections. Epithelial cells of PII are characterized by high and dense brush border at the apical side, elaborate folding of the lateral cell membrane and large basal extracellular labyrinth confined by a system of meandering cell extensions. Basal cytoplasmic zone, apical cytoplasmic zone, nuclei, mitochondria and apical small vacuoles were accessible for X-ray microanalysis. Concentrations of Na, Mg, P, S, Cl and K were different in the cytoplasmic zones along the basal-apical axis of the cell and in the organelles. PII cells lacked an apical tubulovesicular apparatus, instead they displayed an apical zone of smooth clear vesicles and small apical vacuoles. After freeze-drying, the small apical vacuoles and the smooth clear vesicles contained flocculent mass-dense material. Small apical vacuoles showed high concentrations of Mg (229 mmol/kg water), Na (132 mmol/kg water) and Cl (148 mmol/kg water). Sequestration of Mg in vesicles and small apical vacuoles and subsequent exocytosis between the microvilli of the brush border are supposed to be important steps in the transepithelial transport (tubular secretion) of magnesium by PII cells of marine fish.

Effects of nIFN beta and rIFN gamma on growth and morphology of two human melanoma cell lines: comparison between two- and three-dimensional culture

We compared the anti-proliferative effects of natural interferon beta (nIFN beta) and recombinant interferon gamma (rIFN gamma) on 2 human melanoma cell lines, IGRI and SK-Mel28, grown in 2-dimensional monolayer and in 3-dimensional spheroid culture. In monolayer culture, growth of both lines was inhibited in a dose-dependent manner by 5-day treatments with IFN in concentrations ranging between 1 and 5,000 IU/ml. Incubations with 120 IU/ml nIFN beta or 25 IU/ml rIFN gamma led to a 50% growth inhibition of IGRI cells. A 50% growth inhibition of SK-Me128 cells was obtained with 60 IU/ml nIFN beta, whereas even 5,000 IU/ml rIFN gamma inhibited the growth of this line by only 30%. Growing these melanoma cell lines in 3-dimensional spheroid culture for 5 days reduced their sensitivity to interferon. Growth inhibition values of 50% were achieved with 3,000 IU/ml rIFN gamma or 9,000 IU/ml nIFN beta for IGRI spheroids and 10,000 IU/ml nIFN beta for SK-Me128 spheroids, while 10,000 IU/ml rIFN gamma reduced the growth of SK-Me128 spheroids by only 25%. Outgrowth tests showed that the proliferative capacity after 5-day incubations with IFN was only reduced in IGRI spheroids treated with high doses of nIFN beta. The macroscopically observed increased density of interferon-treated spheroids could be confirmed by light microscopy as corresponding to reduced intercellular space in these spheroids. Scanning electron microscopy furthermore showed variations on the surface of IFN-treated spheroids as well as in cellular organization and structures between cells, hinting at a possible involvement of extracellular matrix substances in the reaction to interferons.(ABSTRACT TRUNCATED AT 250 WORDS)

Electron probe X-ray microanalysis of epithelial cells: aspects of cryofixation

Content and distribution of diffusible ions in epithelial cells were studied by scanning transmission electron microscopy and energy dispersive electron probe X-ray microanalysis of freeze-dried cryosections from trout kidney, rat liver and Malpighian tubules of Drosophila larvae. Cryofixation of small excised kidney and liver samples by rapid immersion into liquid propane resulted in intracellular K/Na-ratios < 1. In contrast, K/Na-ratios > 7 were obtained after in situ cryofixation by means of a cryopunching device which allows tissue pieces to be frozen during excision from the intact organ. Isolated hepatocytes cryofixed in a small droplet of culture medium had a K/Na-ratio of 3.7. After culturing the hepatocytes, the K/Na-ratio increased to 24. Effects of extracellular media of different composition on the intracellular element content were studied. Malpighian tubules of Drosophila larvae were cryofixed by rapid immersion into liquid propane, and the distribution of K across the cells forming the tubules from the basal to the apical cell membrane was measured. An increasing K gradient was found from the intermediate to the apical cytoplasm. The intracellular K distribution was dependent on ions and transport inhibitors present in the fluid surrounding the Malpighian tubules within the larvae. Content and distribution of ions in epithelial cells sensitively depend on the physiological state immediately before cryofixation. Thus, electron probe X-ray microanalysis of cells and cell functions requires careful selection and control of the cell system to be studied.

Platelet Survival in Healthy Volunteers After Storage with N-(2-mercaptopropionyl)-glycine

The sulphhydryl group containing drug N-(2-mercaptopropionyl)-glycine (MPG) was tested as a cytoprotective substance for storage of human platelets for transfusion. Autologous platelets stored for 48 h at 21 ± 1°C in the absence (control-platelets) or in the presence (MPG-platelets) of MPG, respectively, were labelled with Indium-III oxine and retransfused into the healthy donors. Significantly higher survival and a higher spleen/liver-ratio were obtained using stored MPG-platelets compared to stored control-platelets. Additionally, a very strong correlation was found between the percentage of discocytes counted after incubation of stored platelets in fresh plasma in vitro and the survival of stored platelets after retransfusion in vivo.

Renal tubule of dogfish, Scyliorhinus caniculus: a comprehensive study of structure with emphasis on intramembrane particles and immunoreactivity for H(+)-K(+)-adenosine triphosphatase

The ultrastructure of renal tubule cells was studied in the European lesser spotted dogfish by the evaluation of thin sections and freeze fracture replicas. Computer-assisted three-dimensional reconstruction of entire nephrons was performed. The distinction of nephron segments and collecting tubule was made using results of previous histological work. The first proximal tubule segment (PI) consists of two subsequent portions, PIa and PIb. PIa is a component of the lateral countercurrent bundle, and PIb, which displays an apical tubulovesicular apparatus and an extended lysosomal compartment, is located in the vicinity of the glomeruli. Rod-shaped intramembrane particles were detected in PIa. The second proximal tubule segment (PII) is a special segment in elasmobranch and teleost fish. PII differs largely from PI in cell morphology and function. The apical cytoplasm was filled with small clear vesicles, and an apical endocytic apparatus was lacking. In the apical cell membrane, rod-shaped particles were revealed by freeze fracture. The apical tight junctions of PI and PII consisted of seven to ten meandering strands. The distal nephron was subdivided into two major segments: early distal tubule (EDT) in the lateral countercurrent bundles and late distal tubule (LDT) in the mesial tissue. The EDT showed marked amplification of basolateral cell membranes. The tight junctions displayed a low number of continuous parallel strands, which is also characteristically found in the diluting segments of other vertebrates. LDT cells showed cytoplasmic studs and rod-shaped intramembraneous particles at the apical cell membrane, thereby resembling type A intercalated cells of collecting duct. The collecting tubule (CT) emerged from the LDT and was part of the countercurrent arrangement inside the lateral bundles. Tight junctions of LDT and CT consisted of many meandering strands in a honeycomb pattern. With immunohistochemistry, binding sites of a polyclonal antibody against an extraplasmic portion of rat gastric H(+)-K(+)-adenosine triphosphatase (ATPase) were observed at the apical cell membrane of PIa, PII, and LDT. From the colocalization of binding sites for the antibody against the transport enzyme with rod-shaped intramembrane particles, we assume that these might be the morphological correlate of gastric H(+)-K(+)-ATPase-like enzyme in the renal tubule.

Heterogenous distribution of glycoconjugates in the kidney of dogfish Scyliorhinus caniculus (L.) with reference to changes in the glycosylation pattern during ontogenetic development of the nephron

Eight fluorochrome-coupled lectins with different sugar specificities were applied to cryosections of dogfish kidney. Despite profound differences in renal architecture between elasmobranch fish and other vertebrates, the sequence of nephron segments as revealed by the lectin-binding pattern was rather similar to that of tetrapodes. Wheat germ agglutinin (WGA) bound to cell membranes of epithelial cells of glomeruli, proximal and distal tubules, their basement membranes, the collecting tubule, and epithelial cells. Among other broadly binding lectins were Ricinus communis agglutinin I (RCA-I), soybean agglutinin (SBA), peanut agglutinin (PNA), Lycopersicon esculentum agglutinin (LEA), and Jacalin, all of which marked proximal as well as distal portions of the renal tubule. Dolichos biflorus agglutinin (DBA) did not react with any renal structure. Ulex europaeus agglutinin I (UEA-I), which indicates the presence of alpha-L-fucose, very strongly and specifically marked single epithelial cells of the early distal nephron, all epithelial cells of the late distal tubule, the beginning of the collecting tubule in the mesial tissue zone, and single cells in the end portion of the collecting tubule in the lateral bundles. Binding of UEA-I to receptors of distal nephron cells could be useful for the identification of these cells in functional studies employing teased tubule and/or isolated cell preparations. Binding of UEA-I to dogfish kidney structures resembles staining with UEA-I conjugates of late distal tubules and collecting tubules in the kidneys of frog and other, higher vertebrates. Epithelial cells of early developmental stages showed, very rarely, binding sites for most lectin-fluorochrome conjugates. A large number of lectin binding sites was observed in the extracellular matrix of fibroblast layers surrounding the early anlage and the S-shaped body. Lectin binding sites of the nephron epithelia appeared in a sequential manner in the next stages of development of the nephron. Ontogenetic and phylogenetic aspects of the merging region between nephron proper (late distal tubule) and collecting system (collecting tubule) are discussed.

Abnormalities in the regulation of blood platelet free cytosolic calcium in malignant hyperthermia. I. Human platelets

The effect of halothane on the regulation of blood platelet free cytosolic calcium was investigated in Quin-2-loaded cells from patients susceptible to Malignant Hyperthermia (MH) and healthy controls, respectively. The resting level of free cytosolic calcium was slightly, but statistically significantly, enhanced in platelets from patients (90 +/- 10 nM vs 110 +/- 35 nM). Halothane induced a dose-dependent, rapid Ca2+ release from intracellular stores both in normal and in MH derived cells, but the resulting increase in cytosolic calcium was significantly higher in the latter (2 mM halothane: [Ca2+]i = 117 +/- 12 nM vs 218 +/- 117 nM; 4 mM halothane: 225 +/- 35 nM vs. 417 +/- 201 nM). Whereas in platelets from healthy donors a complete reversibility of the halothane effect could be observed within 30-45 min, the cytosolic Ca2+ transients in platelets from patients were different from those in normals either in a higher initial peak or in a diminished decline velocity or in both. The basal Ca2+ permeability of the platelet plasma membrane was very low. Generally, halothane caused a dose-dependent increase in Ca2+ permeability. However, the influx of external calcium was significantly higher in platelets from patients than in controls (2 mM halothane: delta [Ca2+]i = 69 +/- 12 nM vs 135 +/- 63 nM; 4 mM halothane: 127 +/- 33 nM vs. 258 +/- 111 nM). Combining the results, the suggestion can be made that susceptibility to MH is characterized by a generalized membrane defect.(ABSTRACT TRUNCATED AT 250 WORDS)

Developing nephrons in adolescent dogfish, Scyliorhinus caniculus (L.), with reference to ultrastructure of early stages, histogenesis of the renal countercurrent system, and nephron segmentation in marine elasmobranchs

Light and electron microscopy of the excretory kidney of adolescent dogfish, Scyliorhinus caniculus (L.), revealed immature and mature nephrons as well as four developmental stages of nephrons. At stage I the nephron was characterized by a condensed mass of mesenchymal cells in the center of several concentric layers of connective tissue. At stage II of the nephron, the S-shaped body was an elongate cyst with a high prismatic epithelium that was connected by a developing collecting tubule with the collecting duct system. At stage III, the developing nephrons already possess the essential features of the mature nephron but lack complete differentiation. Developing renal corpuscles had one afferent arteriole and two efferent vessels. Developing tubules ran four times between the lateral bundle zone and the mesial tissue zone before they joined the collecting duct system. A continuous sheath of flat cells, encompassing the collecting duct system, extended around the developing lateral bundle. A rudimentary central vessel ran from the developing lateral bundle to the venous sinusoid capillaries between the mesial convolutions. Developmental stage IV was similar to the mature nephron, however, renal corpuscles and tubular segments were smaller than those of mature nephrons. Conclusive evidence for morphological homology of elasmobranch nephron segments and collecting tubule-collecting duct system with those of other vertebrates is provided. The origin and nature of the central vessel and the bundle sheath is clarified. These specific structures of marine elasmobranch kidney supposedly are of great functional relevance for the renal countercurrent system that in turn is essential for ion- and osmo-regulation.

High-resolution scanning electron microscopy of frozen-hydrated and freeze-substituted kidney tissue

Inner surfaces and fracture faces of rabbit kidney tissue were investigated with high-resolution scanning electron microscopy using two different cryopreparation techniques: (i) for the observation of fracture faces, cryofixed tissue was fractured and coated in a cryopreparation chamber dedicated to SEM, vacuum transferred onto a cold stage and observed in the frozen-hydrated state; (ii) for the observation of inner surfaces of the nephron, water was removed after freezing and fracturing by freeze substitution and critical-point drying of the tissue. By both methods, macromolecular structures such as intramembranous particles on fracture faces and particles on inner surfaces were imaged. The latter method was used to investigate in more detail surface structures of cells in the cortical collecting duct. These studies revealed a heterogeneity of intercalated cells not described thus far.

Renal blood vascular system in the elasmobranch, Raja erinacea Mitchill, in relation to kidney zones

The arrangement and structure of renal blood vessels were studied in a marine skate with injection of silicone rubber and methacrylate resin after intravenous administration of epinephrine and perfusion fixation. The methacrylate casts were investigated with the scanning electron microscope. Histology was performed by light and transmission electron microscopy of serial sections. The course of the blood vessels is described in relation to the renal zones of lateral bundles and mesial tissue. Each nephron performs two loops in the lateral bundles and two coilings in the mesial tissue before it joins the collecting duct system. The lateral bundles contain an elaborate countercurrent arrangement of neck segment, proximal tubule segment PIa, early distal tubule segment, and collecting tubule. Within the bundles, the nephron portions are associated with a blind-ended central vessel, which is connected with the venous sinuses of the mesial tissue. The microcirculatory bed around the bundles is supplied with arterial blood via small bundle arteries that originate from the intrarenal arteries in parallel to the afferent arterioles of the glomeruli. The efferent arterioles of the glomeruli convey their blood to the peritubular sinuses of the mesial tissue, which is largely irrigated with venous blood of the renal portal system. The mesial tissue, containing the proximal tubule segments PIb and PII, intermediate segment, and late distal tubule segment LDTb, receives venous blood from the caudal vein and the lateral musculature via afferent renal and intrarenal veins and from the efferent arterioles of the glomeruli and venules of the microcirculation of the bundles. The sinuses are drained by efferent renal veins via efferent intrarenal veins. By comparing the renal structures of the skate with those of dogfish, a unique type of circulation--as related to nephron segments, renal zones, and fine structure of the wall of the vessels--is revealed in marine elasmobranchs of different evolutionary levels.

Glomerular permselectivity to serum proteins in rainbow trout (Salmo gairdneri)

Changes in glomerular filtration rate (GFR) were induced in the unanesthetized rainbow trout by short-term adaptation from freshwater (FW) to brackish water (BW, 50% seawater) to investigate the effect of altered glomerular function on the glomerular permselectivity to endogenous serum proteins in vivo. Protein patterns of serum and urine were obtained by nondenaturing polyacrylamide gradient gel electrophoresis. In the serum, high-molecular-weight proteins dominate by 83.1 +/- 8.16%, and total serum protein concentrations were 3.25 +/- 0.32 (FW) and 3.12 +/- 0.16 g/100 ml (BW). The urinary protein concentration increased from 16.0 +/- 1.41 (FW) to 42.8 +/- 11.0 mg/100 ml (BW), whereas GFR and urine flow rate, both linearly related, decreased from 4.55 +/- 0.34 (FW) to 1.84 +/- 0.11 (BW) ml.h-1.kg-1 and from 2.31 +/- 0.19 (FW) to 0.56 +/- 0.02 (BW) ml.h-1.kg-1, respectively. The fractional clearance of protein increased exponentially at decreased GFR. This suggests increased glomerular filtration of serum proteins due to altered glomerular hemodynamics.

The relation of membrane-ATPase activity with congestive heart failure

By the use of the phosphate method the activity of the (Na+ + K+)-ATPase system (E. C. 3.1.6.1.) of human left ventricle was measured in one tissue sample each obtained from 47 autopsied patients. The subjects between the ages of 20 and 79 years had suffered from congestive heart failure of different functional classes NYHA), from diseases of the heart and circulation, or from tumors. Only 23 of the patients of the entire group took digitalis glycosides. With the exception of one sample (8.58 mumol Pi.mg-1.h-1), the enzyme activity amounted from 0.45 to 4.84 mumol Pi.mg-1. The ATPase activity depends on the age (A), the functional classes of congestive heart failure (CF; CF greater than A), and the time between death and autopsy. Chronic hypoxic alterations decreased the enzyme activity. Digitalization did not influence the post-mortem enzyme activity. Due to the small therapeutic range of digitalis glycosides and a distinctly reduced ATPase activity of the ageing patient, enhanced glycoside maintenance doses will not improve myocardial contractility, but provoke arrhythmias.

Adaptation of renal function to hypotonic medium in the winter flounder (Pseudopleuronectes americanus)

The kidneys of winter flounders transferred to hypotonic medium were investigated for glomerular and tubular handling of fluid and electrolytes and for the urinary excretion of proteins. Media were sea water (925 mosm X kg-1) and brackish water (70 mosm X kg-1). In sea water, the urine was hypertonic to the plasma in 7 fish of this study. Urine flow rate was correlated with the GFR. After adaptation to brackish water a delay of 1 to 3 days was observed until the kidneys switched from fluid retention to the excretion of large amounts of dilute urine. GFR and urine flow rate were increased from 0.61 +/- 0.08 to 1.58 +/- 0.29 ml X h-1 X kg-1 and from 0.14 +/- 0.02 to 0.68 +/- 0.08 ml X h-1 X kg-1, respectively (mean +/- SEM). With increased filtered load the tubular reabsorption of fluid decreased from 74 +/- 2.4% to 45 +/- 11.2%. The excretion rates of sodium and potassium were increased due to decreased fractional sodium and potassium reabsorption. The urinary excretion of divalent cations, however, was reduced because the net tubular reabsorption of calcium was increased and the net secretion of magnesium was diminished. Both the urinary total protein concentration and the protein pattern showed no significant change, but the rate of protein excretion was increased from 0.21 +/- 0.04 to 0.60 +/- 0.05 mg X h-1 X kg-1. The comparison of protein patterns obtained from urine and serum samples revealed that high molecular weight (HMW) proteins prevail in the serum whereas low molecular weight (LMW) proteins dominate in the urine. The diminished quantity of the HMW-protein fraction in the urine thus may reflect size selectivity of the glomerular filtration barrier for serum proteins also in the winter flounder.

Stimulation of renal phosphate secretion in the stenohaline freshwater teleost: Carassius auratus gibelio Bloch

1. Renal excretion of phosphate in the Prussian carp was modulated by tubular reabsorption and tubular secretion. 2. Under the conditions of an i.v. phosphate-load during which the plasma concentration of phosphate was doubled, 65% of the phosphate load was excreted by the kidney, mainly by tubular secretion. 3. The renal clearance of PAH markedly exceeded the clearance of polyfructosan which could be used for the measurement of the GFR. 4. A transport maximum for tubular PAH secretion was reached at plasma concentrations of about 250 mumol/l.

Treatment of duodenal ulcer with low-dose antacids

The aim of the present investigation was to compare the efficacy of a low-dose antacid (Maalox 70, 280 mmol/day) with that of the H2-receptor antagonist cimetidine (Tagamet, 200 mg three times daily and 400 mg/day) after 14 and 28 days in the treatment of duodenal ulcer. The prospective multicentre study included 171 patients with endoscopically confirmed duodenal ulcers. The patients were randomly assigned to the treatment groups with antacid containing Mg and Al hydroxide (M)(4 X 70 mmol/day; n = 86) or to the group receiving cimetidine (T) (1000 mg/day; n = 85). The two treatment groups were matched for age, sex, drinking and smoking habits, and drug use. Endoscopic examinations were carried out before the start of treatment and 14 days later. If the ulcer was still present at this time, the second endoscopic examination was done after a further 14 days. Endoscopically, the ulcer had healed at 14 days in 38.8% (M) and in 34.9% (T) and at 28 days in 80.0% (M) and 74.7% (T), respectively. The healing rate did not differ significantly between the two treatment groups. Complaints, measured as percentage of days per week with upper abdominal pain, were significantly reduced in both groups. No significant differences were found between the two treatment groups with regard to pain relief or side effects. Treatment had to be abandoned in one patient receiving antacid because of diarrhoea and in one patient receiving cimetidine because of the absence of any response.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical and morphological differences in the kidney zones of the elasmobranch, Raja erinacea mitch

The histological investigation of the kidney of the skate Raja erinacea revealed a thin cap of dorsal bundles, which contain segments of single nephrons that are arranged separately in a countercurrent manner, and a large ventral zone, where the second proximal segments (PII) and parts of the lower nephron are located. This zonation is apparent in fresh, unfixed material and makes it possible to separate small tissue samples under a dissecting microscope. The osmolality in both zones does not differ. The dorsal bundle zone had a lower urea concentration and a higher sodium concentration than the ventral zone. The differences in the mean concentrations of the tissue samples indicate a gradient for the two substances along the bundles. Determinations of amounts of water and solutes per mg solute-free, dry tissue of the two zones, showed that the amounts of water, total osmolytes, Na and K were greater in the bundle zone than in the ventral zone, while the amount of urea was identical in the two zones. This indicates that the lower urea concentration in the bundle zone is established through an accumulation of Na and water in the interstitium. The countercurrent arrangement of very early and late segments of single renal tubules supports the concept of passive reabsorption of urea in the kidney of the marine elasmobranch.

Ultrastructure and adrenergic innervation of preglomerular arterioles in the euryhaline teleost, Salmo gairdneri

The opisthonephric kidney of the rainbow trout was investigated by light- and electron microscopy and a fluorescent-histochemical technique for biogenic amines was used. Preglomerular sphincters at the origin of afferent arterioles are present in this euryhaline teleost. The branching point of the afferent arteriole is characterized by (i) the formation of a right angle with the parent vessel, (ii) circularly arranged smooth muscle cells of the tunica media, (iii) additional circularly arranged smooth muscle cells intercalated between endothelium and tunica media, and (iv) a collar-like arrangement of several large endothelial cells with elaborate marginal folds and abundant myoendothelial junctions. A dense adrenergic innervation displaying specific fluorescence was found along the terminal arterioles and afferent arterioles, and conspicuously at the preglomerular sphincters. These results are suggestive of a neural participation in kidney function. They are discussed on the basis of recent evidence from pharmacological and physiological experiments for neural involvement in glomerular intermittency.