The mu1, mu2, delta, kappa opioid receptor binding profiles of methadone stereoisomers and morphine

The binding affinities of racemic methadone and its optical isomers R-methadone and S-methadone were evaluated for the opioid receptors mu1, mu2, delta and kappa, in comparison with that of morphine. The analgesic R-methadone had a 10-fold higher affinity for mu1 receptors than S-methadone (IC50 3.0 nM and 26.4 nM, respectively). At the mu2 receptor, the IC50 value of R-methadone was 6.9 nM and 88 nM for S-methadone, respectively. As expected, R-methadone had twice the affinity for mu1 and mu2 receptors than the racemate. All of the compounds tested had low affinity for the delta and kappa receptors. This result suggests that S-methadone does not essentially contribute to opioid effect of racemic methadone. R-methadone has a receptor binding profile which resembles that of morphine.

Enantioselective high-performance liquid chromatographic method for the determination of methadone in serum using an AGP and a CN column as chiral and analytical column, respectively

A simple and sensitive HPLC method with ultraviolet absorption detection at 200 nm is described for the determination of methadone enantiomers in human serum, using dextropropoxyphene as an internal standard and organic solvent extraction. Separation was performed on two serially coupled columns, CN and Chiral AGP, with a mobile phase consisting of acetonitrile, dimethylocytlamine and phosphate buffer. Using 1.0 ml of serum, 5 nmol/1 of each enantiomer could be determined with an acceptable precision. No interactions from several drugs were observed. The method has been successfully used in a pharmacokinetic study. More than 2500 serum samples have been separated on the same AGP column with acceptable selectivity and resolution.

[Vaccination of splenectomized children. Antibody response to Haemophilus influenzae type b conjugate vaccine]

Twenty splenectomized children and adolescents aged four to 18 years were immunized once with a Haemophilus influenzae type b (Hib) polysaccharide tetanus toxoid conjugate vaccine. Prior to vaccination, ten of 20 patients had anticapsular antibodies below what could be considered the minimum protective level in the splenectomized (0.6 microgram per ml), whereas all obtained high antibody levels after vaccination. In addition, one infant with congenital asplenia was vaccinated at two, four, and six months of age, and was shown to respond well after the second and third injections, obtaining serum antibody concentrations of 0.84 and 10.7 microgram per ml respectively. Because asplenic individuals have an increased risk of invasive Hib infection, these data suggest that vaccination of such individuals against Hib may be justified.

Opposite effects of actively and passively acquired immunity to the carrier on responses of human infants to a Haemophilus influenzae type b conjugate vaccine

Vaccination of infants with Haemophilus influenzae type b (Hib) capsular polysaccharide (HibCP) coupled to carrier proteins has proven protective against invasive Hib diseases in several trials. However, insufficient immunogenicity has been noted in certain populations. Therefore, studies analyzing factors influencing the antibody response to conjugate vaccines are needed. In this study, the response to HibCP coupled to tetanus toxoid (TT) was examined in relation to (i) priming with or coadministration of the carrier protein and (ii) the levels of passively acquired maternal TT antibodies. One hundred forty-four infants were vaccinated with HibCP-TT at 5 and 6 months. They were randomized into three groups that received TT as part of a diphtheria-tetanus-polio vaccine at either 6 and 7 months (group A), 5 and 6 months (group B), or 4 and 5 months (group C). Maternally acquired TT antibodies inhibited the anti-HibCP response to the first HibCP-TT dose in groups A and B (r = -0.5 and -0.4, respectively; P < 0.005). In these groups, infants with prevaccination anti-TT levels above the median failed to reach the defined long-term protective level of HibCP antibodies (1 microgram/ml) more often than infants with low prevaccination levels after the first (P = 0.0001) and the second (P = 0.01) doses of HibCP-TT. In contrast, active priming with TT at 4 months resulted in a threefold-higher median level of anti-HibCP (group C; 1.34 micrograms/ml) than in the unprimed group (group A; 0.40 microgram/ml) after the first dose of HibCP-TT (P = 0.01). Coadministration of TT had no enhancing effect (group B; 0.58 microgram/ml). No significant differences between the median anti-HibCP levels were seen after the second HibCP-TT dose (6.72, 9.63, and 11.44 micrograms/ml in groups A, B, and C, respectively; P = 0.25).

[Finger tip injuries. A comparative study of silver sulfadiazine and fucidin gauze]

Eighty-eight superficial finger-tip lesions were randomized after thorough cleaning to either silver sulphadiazine treatment of Fucidin fusidic acid gauze. In the silver sulphadiazine group the wounds were covered with a non-sterile PVC gloce and redressed at least every third day; in the other group Fucidin gauze was applied and a tubigauze dressing was left in situ for ten days, after which a new dressing was applied. All patients were treated until healed and followed for at least six months after injury. Patients in the silver sulphadiazine group required shorter time for healing and shorter sick leave. The treatment is recommended because of the easy procedure and the good results.

General surgery in patients aged 80 years and older

This study reviews 594 surgical admissions, of patients aged 80 years and older, to departments of general surgery during 1 year. Half of the patients were admitted as emergencies and 60 per cent underwent surgery. The operative mortality rate was 8 per cent and the overall mortality rate for all admissions 9 per cent. The number of complications and the mortality rate after surgery increased in emergency cases and in patients with coexisting disease. Of all admissions, 72 per cent were uncomplicated and in 70 per cent patients could be discharged directly home; such patients do not generally take up beds and are discharged as soon as medical care is no longer indicated. The number of admissions of patients over 80 years of age will increase by about 30 per cent during this decade and, unless additional resources are provided to meet this challenge, new standards must be considered for the distribution of resources and of indications for surgery in both young and old.

Relation between enzyme-linked immunosorbent assay and radioimmunoassay for detection of antibodies to the capsular polysaccharide of Haemophilus influenzae type b

The measurement of antibodies to the capsular polysaccharide (PRP) of Haemophilus influenzae type b (Hib) is important because vaccines inducing such antibodies are now available. We developed and evaluated an enzyme-linked immunosorbent assay (ELISA) for detection of these antibodies based on direct coating of the plates with tyraminated PRP. The assay fulfilled the requirements for parallel line assays; it was sensitive, specific, and reproducible with a coefficient of variation between days of 19%. Results from the ELISA were compared with results from radioimmunoassay and a correlation coefficient of 0.93 was found. Results obtained by the two methods were proportional and the relation was independent of the antibody level. The relation between them was also unaffected by the contribution of different antibody isotypes, indicating that these were measured to the same extent by both methods. ELISA employing direct coating of the plates with tyraminated PRP represents a useful alternative for detection of antibodies when studying immunogenicity of Hib vaccines.

Antibody response to a Haemophilus influenzae type b polysaccharide tetanus toxoid conjugate vaccine in splenectomized children and adolescents

20 children and adolescents 4-18 years old and splenectomized for various reasons (spherocytosis (n = 6), idiopathic thrombocytopenia (n = 8), other (n = 6)) were immunized once with a Haemophilus influenzae type b (Hib) polysaccharide tetanus toxoid conjugate vaccine. Prior to vaccination 10/20 patients had anticapsular antibodies below what could be considered the minimum protective level in splenectomized (0.6 micrograms/ml), whereas all obtained high antibody levels after vaccination. In addition 1 infant with congenital asplenia was vaccinated at 2,4 and 6 months of age, and was shown to respond well after the second and third injection with serum antibody concentrations of 0.84 and 10.7 micrograms/ml respectively. Because asplenic individuals have an increased risk of invasive Hib infection, these data suggest that vaccination of such individuals against Hib may be justified.

Stereospecific gas chromatographic method for determination of methadone in serum

rac-Methadone is used clinically for the chronic maintenance treatment of heroin addiction and for the relief of pain. As the pharmacological activity of methadone is due primarily to the (-)-(R)-enantiomer, stereospecific measurements of methadone serum concentrations in methadone-treated patients are expected to be more relevant for clinical studies than earlier described total drug measurements. This study describes a stereospecific gas chromatographic (GC) method for the determination of methadone in serum. The extracted methadone was derivatizised with (-)-menthyl chloroformate. The diastereometric derivatives were analysed by GC on a capillary column and detected with a nitrogen-phosphorus detector. The resolution factor obtained for the methadone enantiomers was 1.1 with a relatively short time of analysis (30 min). By analysing the pure (-)-(R)-enantiomer, no racemization was seen during the analysis. The lower limit of quantitation was 75 nmol/l for each enantiomer. Measurements of the ratio between (-)-(R)- and (+)-(S)-methadone concentrations in serum from five methadone-treated patients showed interindividual differences (range 0.5-1.1). The patient results correlated well with those from another GC method measuring total methadone.

Haemophilus influenzae type b infections: secondary cases and recurrent disease

Invasive Haemophilus influenzae type b infections in Denmark have not been known to lead to secondary cases, and recurrent disease has not been observed. Three case histories are presented and the literature reviewed. Secondary disease occurs more often among household contacts than among day-care contacts, which probably is due to genetic factors. The same factors might also influence the risk of contracting recurrent disease. Parents should be informed of the risk and promptly have their children medically evaluated in case of febrile illness. Epidemiological data from Denmark, however, do not provide background for the recommendation of rifampicinprophylaxis to patients with Hib-infection or their contacts.

Antibiotic susceptibility of invasive Haemophilus influenzae type b isolates in Denmark in 1988 and 1989

A system for surveillance of invasive Haemophilus influenzae type b infections in Denmark yielded 135 strains isolated from blood or cerebrospinal fluid from August 1988 through December 1989. The susceptibility of the strains to 7 antibiotics was investigated by an agar dilution method. Ceftriaxone was found to be the most active drug followed by cefotaxime, ceftazidime, rifampicin, ampicillin, cefuroxime, and chloramphenicol. Except for ampicillin the MICs for the individual antibiotics were similar. Seven strains (5.2%), which all produced beta-lactamase, were resistant to ampicillin. Since H. influenzae type b meningitis in otherwise healthy individuals almost exclusively occurs in children aged 2 months to 4 years, a third generation cephalosporin such as ceftriaxone or cefotaxime may be considered the drug of choice for initial therapy of meningitis in this age group.

Epidemiology of Haemophilus influenzae type b infections among children in Denmark in 1985 and 1986

A retrospective epidemiological study of invasive Haemophilus influenzae type b infections among children in Denmark 1985 and 1986 was carried out and 226 cases were identified. Of these 93% occurred in patients younger than five, corresponding to an annual incidence of 40 cases per 100,000 children aged 0-4 years, 68% occurred in patients younger than two years of age, and 6% in patients younger than six months. The annual incidences of meningitis and epiglottis were 27 and 8 cases, respectively, per 100,000 children aged 0-4 years. Of the 156 cases with meningitis four patients died and seven had severe neurological sequelae. Only 67% of the cases of meningitis had been notified.

Drug utilization in breast-feeding women. A survey in Oslo

In a retrospective questionnaire survey of 885 women who had given birth 3-5 months before, fewer of those who were still breast-feeding at 4 months (n = 645) were using drugs than those who had stopped breast-feeding before 4 months (n = 240), during the 2 week period preceding registration. The average number of doses (Defined Daily Doses/1000 women/day) was 166 and 307, respectively, in that period. The number of doses taken was significantly associated with the use of oral contraceptive agents (p less than 0.005) and young maternal age (p less than 0.05). Most of the variation in drug use between breast-feeding and not breast-feeding mothers was probably due to the greater use of contraception by the latter. The number of drugs used per mother in the 4 month period seemed to be best predicted by her and her infant's disorders. Long-term medication in breast-feeding women included many drugs for which there is incomplete or no data about milk transfer, e.g. salbutamol, clemastine, dexchlorpheniramine, phenylpropanolamine, cromoglycate and levomepromazine. The disorders most extensively treated with drugs in this period were dyspepsia, haemorrhoids and inflammation of the breast. The finding that smoking was associated with early weaning and consumption of alcohol with prolonged breast-feeding calls for further investigation. More information on these drug and health issues to the breast-feeding mother is highly desirable.

Trace element status in alcoholism before and during disulfiram treatment

Trace element status was ascertained in 19 alcoholic patients under long-term treatment with disulfiram and in 12 alcoholic patients treated for the first time; the latter group was re-examined after four weeks of treatment. Both groups were compared to matched controls with a moderate alcohol intake. The copper/zinc ratio in serum was increased in the patients under long-term treatment, and a significant decrease occurred during the first four weeks of treatment in the second group. Blood lead was slightly increased in the second group, but not in the patients under long-term treatment. Blood cadmium was high in both groups, perhaps related to excessive tobacco smoking. Blood mercury concentrations were uniformly low. Urinary nickel excretion in the first group was above reference values, and an increase was seen in the second group during the treatment period. Although trace element concentrations in body fluids may not reflect tissue levels, the results support the notion that trace element balances are influenced by alcoholism and disulfiram treatment.

Carriage and antibiotic susceptibility of Haemophilus influenzae type b and non b in Danish day-care attendees

A study of carriage of Haemophilus influenzae type b (Hib) and non b in Danish day-care facilities, employing a highly selective medium supplemented with three antibiotics and direct detection of the type b capsular antigen by latex-agglutination and coagglutination, was carried out. Of 329 children, 217 (66%) were found to be carriers of Haemophilus influenzae. Among 64 children from day-care centers in which a case of invasive Hib infection had occurred, four carriers of type b were found, whereas no type b carriers were identified among 265 children from unexposed day-care centers (p less than 0.003). Of 217 isolated strains, seven (3.2%) were found to have lowered susceptibility to ampicillin, two (0.9%) to chloramphenicol, two (0.9%) to cefuroxim, and one (0.5%) to cefotaxim.

[Haemophilus influenzae type b vaccines]

Haemophilus influenzae type b (Hib) causes severe invasive infections in children such as meningitis and epiglottitis. Vaccines against Hib are now available. This article describes the background for the development of these vaccines and their composition, it presents available data on immunogenicity and protective efficacy and briefly discusses the need for their use in Denmark.

[Disorders and drug consumption among infants. Does breast feeding have an impact?]

Disorders and drug use were analysed in 885 infants whose mothers responded to a questionnaire approximately four months after birth in Oslo, Norway in 1985. Breast-feeding had no influence on drug use in infants, though a lower incidence of some disorders (diarrhea, constipation, vomiting) was found in infants who were breast-fed for average four months than in infants who were weaned earlier. Use of drugs in infants was positively associated with use of drugs by the mother and with the length of her education. About 75% of the babies had at least one disorder and 60% had received at least one drug during the four month registration period. It was claimed that 85% of the drugs were recommended by a physician or a nurse. Anticolic agents, respiratory agents and dermatologicals were given frequently. The single most used drug was dimethicone. 98% of the 261 infants with colic syndrome were treated with this surface active drug, which has an efficacy similar to placebo. During a two week period preceding registration 12% of all infants and concomitantly 25% of the breast-fed infants were exposed to drugs at least once. The drug intake through breast milk was calculated to be 1/7 of the total drug use (117 infant Defined Daily Doses/1,000 infants/day) in breast-fed babies. Validation of the answers to the written questionnaire by subsequent interview of 96 mothers revealed considerable underreporting in the former; 33% for disorders, 22% for drugs and 18% for infant doses. It is concluded that medication for minor disorders in infancy is quite extensive and often unnecessary. Further informative efforts should be directed at parents, as well as the health workers involved.

[Pulmonary arteriovenous fistula in a newborn infant with hereditary telangiectasis]

A case of pulmonary arteriovenous fistula in a newborn baby suffering from hereditary teleangiectasis is described. 15% of patients with hereditary teleangiectasis develop pulmonary arteriovenous fistulas, most of which do not cause symptoms until adult life. Children with hereditary teleangiectasis should be followed regularly, because of the risk of developing vascular malformations, the most frequent locations being the nasal mucosa, the lungs and the gastrointestinal tract.

Haemophilus influenzae type b infections in adults

31 cases of invasive Haemophilus influenzae type b infections occurred in adults in Denmark during a period of 2 years and 5 months corresponding to an incidence of 0.3/100,000/year. Only 6 patients had no underlying condition. The incidence of H. influenzae type b infections in adults will probably rise in the future, because the increasing use of therapeutic measures affecting the immune system will lead to an increase in the number of susceptible patients.

Assessment of the arterial input curve for [99mTc]-d,l-HM-PAO by rapid octanol extraction

The in vitro conversion of the lipophilic molecule [99mTc]-d,l-hexamethylpropyleneamine oxime [( 99mTc]-d,l-HM-PAO) to a hydrophilic form was studied in saline, plasma, and blood at 37 degrees C by paper chromatography and by octanol extraction. The octanol:saline ratio was 79.9. From this value and the corresponding octanol: plasma and octanol:blood partitioning values, an estimate of the transport of the lipophilic compound by various components of blood was made: 20% is carried in hemoglobin, 53% by the plasma proteins and 27% by the water phases of the red blood cell and plasma. Octanol extraction provided a rapid method for measuring the radiochemical purity (RCP) of lipophilic [99mTc]-d,l-HM-PAO. In saline, the RCP declined with a half-life of more than 1 h. In human plasma and whole blood, the conversion of [99mTc]-d,l-HM-PAO was biexponential due to the differences in the conversion rates of the d and l isomeric forms. The initial half-life representing the conversion rate of the l form was 1.7 min in blood and 1.4 min in plasma, while the conversion half-life of the d form was 7.4 and 24.4 min, respectively. In vivo, the RCP of arterial blood sampled after an i.v. bolus injection showed an initial peak value of 75% (68-79%) during the initial, first passage of the bolus. It declined to approximately 35% (29-40%) after 1.5 min and reached very low levels (about 1%) at 6 to 10 min. Quantitative measurements of cerebral blood flow using [99mTc]-d,l-HM-PAO necessitates a rapid method for RCP determination in arterial blood such as the one described here.

Serial studies of cerebral blood flow using 99Tcm-HMPAO: a comparison with 133Xe

We have compared the regional distribution of 99Tcm-HMPAO with regional cerebral blood flow (rCBF). CBF was measured by single photon emission computerized tomography (SPECT) using a TOMOMATIC 64 after 133Xe inhalation in 41 patients. With the same SPECT device the distribution of 99Tcm-HMPAO was measured after i.v. injection. High resolution (HR) and low resolution (LR) studies were performed yielding a resolution of 6 to 10 mm (HR) and 15 to 20 (LR). 99Tcm-HMPAO images showed close resemblance to xenon-133 CBF tomograms. Only about 20% of the (decay corrected) brain counts were lost during the first 24 h post injection. A slight decrease in contrast was measured comparing side-to-side asymmetry ratios from the serial studies. This loss of contrast is mainly due to back-diffusion and clearance of a part of the 99Tcm-HMPAO complex from the brain. It could be corrected for by a linearization algorithm. The slight loss of contrast will not be of any importance for the clinical use of this tracer complex.

Biodistribution in rats of 99Tcm-labelled human serum albumin

Three different 99Tcm-human serum albumin (HSA) preparations were simultaneously studied by high pressure liquid chromatography (HPLC) and gamma camera techniques in rats. The products contained variable amounts of 99Tcm-human albumin, 99Tcm-tin colloid and a 99Tcm-low molecular weight complex. The biological half life varied from 55 to 132 min and the bladder excretion for the first 60 min from 2 to 31%. Separated HPLC fractions of 99Tcm-albumin and 99Tcm-tin colloid both showed considerably longer biological half life when injected separately than when injected in the unfractionated preparation. A final evaluation of the quality of such products seem to require evaluation in humans.

Central nervous system dysfunction as early sign of neuronal ceroid lipofuscinosis (Batten's disease)

During a survey of neuronal ceroid lipofuscinosis (Batten's disease), two younger siblings of patients were found to have the characteristic vacuolation in 11 to 17 per cent of their lymphocytes. The children were four to five years of age and did not have any overt signs or symptoms of the disease. However, they both had markedly reduced auditory memory-span before decreased vision and funduscopic changes developed. The subsequent course of the disease confirmed the diagnosis. It is concluded that neuronal ceroid lipofuscinosis may affect mental functions much earlier than previously believed.

Anaphylactic reaction to orthoiodohippurate

A case of an anaphylactic reaction following administration of 125I- and 131I-o-iodohippurate in a 32-year-old woman is reported. The patient had a renography performed because of hematuria. She was known to react to an intravenous pyelography previously performed with an anaphylactic shock. The importance of reporting all adverse reactions to radiopharmaceuticals for central registration is stressed.

Evaluation of methods for sizing of colloidal radiopharmaceuticals

Many different quality control methods have been proposed for characterization of colloidal radiopharmaceuticals, as particle size seems to be of importance for the resulting biological distribution. Membrane filtration techniques using polycarbonate sheet filters (Nuclepore) is a simple technique. For a number of products good correlation was obtained to particle sizes measured by photon correlation spectroscopy (Nanosizer). For several preparations an increase in particle size with time was observed.

Reduced systolic blood pressure in fingers of patients with generalized scleroderma (acrosclerosis)

Segmental systolic blood pressure was measured on upper arm, wrist, proximal and middle pahlanx in 10 patients suffering from generalized scleroderma of the acrosclerosis type and in 5 normal. Systolic pressure was measured by the strain-gauge technique before and after abolition of sympathetic vasoconstrictor activity by local heating and by nerve block. Arm and wrist pressures were equal in the two groups, but a significant reduction in finger pressure was found in the patients. Finger pressure was unaltered after sympathetic blockade, both in the patients and in the normals. The pressure drop from wrist to finger in the patients suggests an increased flow resistance in the palmer arch and digital arteries which was probably not caused by an augmented sympathetic vasoconstrictor activity, as sympathetic blockade did not influence finger systolic pressure. Sympathectomy cannot be expected to relieve Raynaud´s attacks in these patients.

Fission MO-99/Tc-99m Generators -- a study of their performance and quality

Five 99mTc-generators, based on fission Mo-99, from five different manufacturers were studied in April and May of 1977 -- with regard to their performance and to the quality of the eluates. The study covers types of generators not already dealt with in a previous publication [5]. One generator was overloaded with Mo-99; one generator had Tc-99m yields below 70%. One generator yielded eluates containing appreciable gamma-emitting impurities other than Mo-99. Two generators yielded eluates containing trace amounts of Al+++. The content of alpha- and pure beta-emitting nuclidic impurities (other than Tc-99) were in all cases below the limits set in the DLS 79 [2] monograph on Tc-99m pertechnetate obtained from fission Mo-99.

Amino acid transport in human ciliary epithelium

A statistical study of the co-variation of the concentrations of 19 amino acids and related compounds from 21 persons was performed as a factor analysis of Caq/Cpl and of Caq. Six factors explained about 83% of the observed variation. Factor 1 showed a correlation to alpha-amino-N-butyric acid, valine, methionine, isoleucine, leucine, tyrosine and phenylalanine, factor 2 to lysine, histidine, arginine and glutamine (containing serine), factor 3 to taurine and proline, factor 4 to glycine and cystine, factor 5 to urea and factor 6 to glutamic acid. Only alanine and threonine showed a correlation to different factors in the Caq/Cpl- and the Caq-matrix. This correlation of groups of substances to different and independent factors is considered to be an argument in favour of the existence of six transport systems in the ciliary epithelium for the investigated substances.

Microbial contamination of radionuclide generators

Technetium-99m generators were grossly contaminted using 5 different strains of microorganisms. Elution of the generators showed that the number of microorganisms was reduced by a factor of 10(4)-10(6). There were no indications that the generators would support bacterial growth. It is concluded that it would be acceptable from a microbiologic point of view to omit autoclaving and membrane filtration of the final product provided that proper aseptic techniques are applied.

Comparative evaluation of 99mTc-generators

A total of 34 99mTc-generators from eight different manufactures were studied in 1974 and 1975 with regard to their performance and to the quality of the eluates. With some exceptions the generators performed well and proved their ability to act as a reliable source of 99mTc-pertechnetate. Two cases of mechanical malfunction and two cases with a low elution yield of 99mTc were observed. Four generators were overloaded with 99Mo. The 99mTc-pertechnetate did in most cases fulfil the requirements of the Nordic Pharmacopeia.

Flow along the Gut and Intestinal Absorption of Salt and Water in Euryhaline Teleosts: A Theoretical Analysis

1. In euryhaline teleosts the transmural salt and water flow and the flow and concentration changes along the gut were simulated by analogue computation. The purpose was to elucidate the interaction of and sensitivity to the parameters of the system particularly with respect to intestinal water absorption. The simulations were based on data obtained from the yellow European eel, the rainbow trout and the cyprinodont Aphanius dispar.

2. When the experimental values for drinking rate, maximal NaCl absorption rate and concentration at half-maximal absorption rate, osmotic permeability coefficient, solute-linked water flow, and concentrations in the gut were used in the model, good consistency was achieved, and predictions could be made.

3. The simulations demonstrated a close linkage between drinking rate and maximal NaCl absorption rate. A large water absorption was only possible close to an optimal drinking rate for each value of maximal NaCl transport rate. The water absorption was little sensitive to the osmotic permeability coefficient of the intestinal wall.

4. As a means of adaptation to waters of high salinity an increase in maximal NaCl absorption rate was shown to be very costly for energetic reasons. This supports indirectly the concept that the osmotic permeability of the gills must go down. The increase in plasma osmolality was a useful part of the adaptation.