Persistence of arctic-alpine flora during 24,000 years of environmental change in the Polar Urals

Plants adapted to extreme conditions can be at high risk from climate change; arctic-alpine plants, in particular, could "run out of space" as they are out-competed by expansion of woody vegetation. Mountain regions could potentially provide safe sites for arctic-alpine plants in a warmer climate, but empirical evidence is fragmentary. Here we present a 24,000-year record of species persistence based on sedimentary ancient DNA (sedaDNA) from Lake Bolshoye Shchuchye (Polar Urals). We provide robust evidence of long-term persistence of arctic-alpine plants through large-magnitude climate changes but document a decline in their diversity during a past expansion of woody vegetation. Nevertheless, most of the plants that were present during the last glacial interval, including all of the arctic-alpines, are still found in the region today. This underlines the conservation significance of mountain landscapes via their provision of a range of habitats that confer resilience to climate change, particularly for arctic-alpine taxa.

Meta-analysis reveals that pollinator functional diversity and abundance enhance crop pollination and yield

How insects promote crop pollination remains poorly understood in terms of the contribution of functional trait differences between species. We used meta-analyses to test for correlations between community abundance, species richness and functional trait metrics with oilseed rape yield, a globally important crop. While overall abundance is consistently important in predicting yield, functional divergence between species traits also showed a positive correlation. This result supports the complementarity hypothesis that pollination function is maintained by non-overlapping trait distributions. In artificially constructed communities (mesocosms), species richness is positively correlated with yield, although this effect is not seen under field conditions. As traits of the dominant species do not predict yield above that attributed to the effect of abundance alone, we find no evidence in support of the mass ratio hypothesis. Management practices increasing not just pollinator abundance, but also functional divergence, could benefit oilseed rape agriculture.

A cell-based infection assay identifies efflux pump modulators that reduce bacterial intracellular load

Bacterial efflux pumps transport small molecules from the cytoplasm or periplasm outside the cell. Efflux pump activity is typically increased in multi-drug resistant (MDR) pathogens; chemicals that inhibit efflux pumps may have potential for antibiotic development. Using an in-cell screen, we identified three efflux pump modulators (EPMs) from a drug diversity library. The screening platform uses macrophages infected with the human Gram-negative pathogen Salmonella enterica (Salmonella) to identify small molecules that prevent bacterial replication or survival within the host environment. A secondary screen for hit compounds that increase the accumulation of an efflux pump substrate, Hoechst 33342, identified three small molecules with activity comparable to the known efflux pump inhibitor PAβN (Phe-Arg β-naphthylamide). The three putative EPMs demonstrated significant antibacterial activity against Salmonella within primary and cell culture macrophages and within a human epithelial cell line. Unlike traditional antibiotics, the three compounds did not inhibit bacterial growth in standard microbiological media. The three compounds prevented energy-dependent efflux pump activity in Salmonella and bound the AcrB subunit of the AcrAB-TolC efflux system with KDs in the micromolar range. Moreover, the EPMs display antibacterial synergy with antimicrobial peptides, a class of host innate immune defense molecules present in body fluids and cells. The EPMs also had synergistic activity with antibiotics exported by AcrAB-TolC in broth and in macrophages and inhibited efflux pump activity in MDR Gram-negative ESKAPE clinical isolates. Thus, an in-cell screening approach identified EPMs that synergize with innate immunity to kill bacteria and have potential for development as adjuvants to antibiotics.

Breastfeeding initiation: An in-depth qualitative analysis of the perspectives of women and midwives using Social Cognitive Theory

OBJECTIVE

to explore women's and midwives' expectations, knowledge and experiences of breastfeeding initiation using Social Cognitive Theory.

DESIGN

a qualitative study using focus group discussions and individual interviews. Breastfeeding initiation was defined for this study as a process within the first 48hours after birth. Data were analysed using qualitative inductive analysis then further deductive analysis using Social Cognitive Theory (SCT).

SETTING AND PARTICIPANTS

a purposefully selected sample of primigravid antenatal and postnatal women (n=18) and practising midwives (n=18) from one Health Board area in Scotland.

FINDINGS

attachment of the baby to the breast at birth was hindered by sleepy babies and the busy unfamiliar hospital environment. These resulted in mothers struggling to maintain their motivation to breastfeed and to develop low self-efficacy. Instinctive attachment was rare. Midwives who considered it was normal for babies to be sleepy and unable to attach or feed at birth did not facilitate instinctive baby behaviour. Midwives sometimes experienced lack of autonomy and environmental circumstances that made women centred care difficult. Furthermore caring for high numbers of women, dependent on their help, resulted in reduced self-efficacy for providing effective breastfeeding support.

KEY CONCLUSIONS

interviewing both women and midwives specifically about initiation of breastfeeding has allowed for deeper insights into this critical period and enabled a comparison between the data obtained from mothers and midwives. The findings suggest that instinctive attachment is not an expectation of either mothers or midwives and results in a loss of breastfeeding confidence in both.

IMPLICATIONS FOR PRACTICE

to facilitate initiation there is a need for more research to develop appropriate maternal and midwifery skills, and make changes to the cultural environment in hospitals. Social Cognitive Theory could be used as a framework in both the antenatal and immediate postnatal period to develop strategies and materials to increase women's and midwives' self-efficacy specifically in initiation.

DNA from soil mirrors plant taxonomic and growth form diversity

Ecosystems across the globe are threatened by climate change and human activities. New rapid survey approaches for monitoring biodiversity would greatly advance assessment and understanding of these threats. Taking advantage of next-generation DNA sequencing, we tested an approach we call metabarcoding: high-throughput and simultaneous taxa identification based on a very short (usually <100 base pairs) but informative DNA fragment. Short DNA fragments allow the use of degraded DNA from environmental samples. All analyses included amplification using plant-specific versatile primers, sequencing and estimation of taxonomic diversity. We tested in three steps whether degraded DNA from dead material in soil has the potential of efficiently assessing biodiversity in different biomes. First, soil DNA from eight boreal plant communities located in two different vegetation types (meadow and heath) was amplified. Plant diversity detected from boreal soil was highly consistent with plant taxonomic and growth form diversity estimated from conventional above-ground surveys. Second, we assessed DNA persistence using samples from formerly cultivated soils in temperate environments. We found that the number of crop DNA sequences retrieved strongly varied with years since last cultivation, and crop sequences were absent from nearby, uncultivated plots. Third, we assessed the universal applicability of DNA metabarcoding using soil samples from tropical environments: a large proportion of species and families from the study site were efficiently recovered. The results open unprecedented opportunities for large-scale DNA-based biodiversity studies across a range of taxonomic groups using standardized metabarcoding approaches.

Relation between ventricular arrhythmias and psychological profile

The association between psychological characteristics and ventricular arrhythmias was investigated in 150 men (50 with manifest IHD, 50 with risk indicators of IHD and 50 healthy men). Arrhythmias were recorded with 24-hour Holter monitoring. Psychological characteristics were assessed by the Emotions Profile Index and the Structured Interview for pattern A behaviour. A depressive emotional state was associated with prognostically severe ventricular arrhythmia in healthy men, but not in men with overt IHD or risk indicators of IHD. When clinical characteristics and age were taken into account, depressiveness was-among healthy men-the second most important factor after high age. The results suggest that-in absence of IHD or other cardiovascular disease-a depressive emotional state may participate in the formation of ventricular arrhythmia.

Relation between arrhythmic sensations, cardiac arrhythmias and psychological profile

The relation between arrhythmic sensations and objective findings of ectopic arrhythmic activity was studied in 150 middle-aged men. Objective arrhythmias were studied by 24-hour Holter monitoring and subjective symptoms assessed by a questionnaire and a dairy protocol during the ECG recording. Psychological characteristics were described by means of a personality inventory, the Emotions Profile Index. No direct relationship was found between subjective symptoms and objective findings of cardiac arrhythmias. Those men, however, who complained of arrhythmic sensations but had no clinically important arrhythmias exhibited a few specific characteristics. They had no signs of organic heart disease and appeared less trustful and more aggressive than those with arrhythmias.

Improvement in the health-related quality-of-life symptoms of hyperparathyroidism is durable on long-term follow-up

BACKGROUND

Subjective symptoms such as decreased energy, chronic fatigue, and depression are associated with hyperparathyroidism. Studies have shown that these symptoms are improved during short-term follow-up after parathyroidectomy. This study evaluates the durability of this subjective improvement in quality-of-life symptoms in a large population of patients with follow-up greater than 1 year after operation.

METHODS

Between 2002 and 2005, 258 patients underwent parathyroidectomy, 100 (81 females and 19 males) of whom were available for this study. The patients were evaluated with a survey based on the Health Outcomes Institute Health Status Questionnaire. Some answers were quantified on a 1 to 6 scale, while others consisted of "yes" or "no" responses. Patients completed a questionnaire prior to parathyroidectomy and postoperatively at 1 month, 3 to 6 months, and 1 to 2 years or greater intervals. Statistical analysis was used to detect changes attributable to parathyroidectomy. A P value <.05 was considered statistically significant.

RESULTS

At 1-month follow-up, patients' perceptions of their overall health, energy level, and mood significantly improved. At 6-month follow-up, significant improvements in muscle strength, health, endurance, and relief of anxiety were documented. At the interval of 1 to 2 years, overall health, energy level, endurance, and relief of anxiety were improved. There was no significant decrement in the quality of life in these patients after parathyroidectomy.

CONCLUSIONS

Parathyroidectomy for hyperparathyroidism is associated with significant lasting improvement in subjective symptoms. The potential durable improvement in these quality-of-life symptoms is a valid indication for parathyroidectomy.

Oral lavage with polyethylene glycol reduces microbial colonization in the gastrointestinal tract of broilers

Oral lavage of 7-wk-old broiler chickens with polyethylene glycol (PEG) was conducted to induce rapid evacuation of the gastro-intestinal tract (GIT) before processing. Three groups of birds were fed ad libitum (FF), subjected to feed withdrawal 12 h before processing (FW), or received 115 mL of PEG by oral lavage 3 h before processing (PEG(L)). The crop, a section of small intestine, and the right cecum were aseptically collected for determination of contents and Gram-negative bacilli (GNB) counts. The PEG(L) effectively cleansed the upper GIT and intestine of treated birds within 3 h before processing. However, the ceca were not completely empty for all the birds subjected to PEG(L). The PEG(L) group had a significantly lower crop and cecal GNB concentrations than the FW group. Birds on FW and PEG(L) treatments had significantly lower GNB concentrations in the small intestine than FF birds. Polyethylene glycol resulted in complete evacuation of the upper GIT, as well as the intestine, within 3 h of use, and significantly reduced GNB concentrations.

Use of a mathematical model to estimate stress and strain during elevated pressure induced lamina cribrosa deformation

BACKGROUND

High intraocular pressure (IOP), which is generally associated with glaucoma, causes lamina cribrosa retrodisplacement and deformation. Shear stress and strain resulting from lamina cribrosa deformation have been implicated in tissue remodeling, changes in retinal astrocyte function and retinal ganglion cell (RGC) death observed in vivo during glaucoma.

METHODS

A mathematical model was developed to describe the lamina cribrosa exposed to elevated intraocular pressure (IOP). The model is based on the bending theory of plates, incorporates anatomical properties of the lamina cribrosa, and provides estimates of its biomechanical properties. The model relates IOP, the parameter normally correlated with glaucoma, and lamina cribrosa retrodisplacement to stress and strain experienced by cells, parameters that may be more closely associated with cell injury.

RESULTS

We estimate that shear strains of 0.05 occur at the edge of a 200 microm thick lamina cribrosa at an IOP of 25 mm Hg. We estimate greater lamina cribrosa deformation and higher shear stress and strain for thinner lamina cribrosa and lamina cribrosa of larger radii.

CONCLUSION

These results may provide better estimates of the stress and strain experienced by cells in the lamina cribrosa and may further our understanding of the forces that contribute to optic nerve degeneration during glaucoma.

Role of viscoelastic properties of differentiated SH-SY5Y human neuroblastoma cells in cyclic shear stress injury

Shear stress and strain lead to neurodegeneration in vivo during head injury, glaucoma, and certain repetitive motion disorders. In vitro, shear stress and strain have been shown to lead to cell injury in a number of models using neurons and neuron-like cells. In the present study we examined the relationship between shear stress, strain, and the extent of cell injury in a cyclic shear stress induced model of cell injury using differentiated SH-SY5Y (human neuroblastoma) cells. Shear stress led to cell strain that increased with increasing stress and diminished upon cessation of shear. Strain rate during cyclic application of shear stress increased by over an order of magnitude from the first to all subsequent cycles, suggesting that the cell and/or its polymer network became more elastic upon cyclic shear stress application. To support this conclusion we measured the degree of cytoskeletal polymerization before and after exposure of cells to cyclic shear stress and found that the fraction of polymerized tubulin in the cell relative to total tubulin decreased by a factor of 2 after six cycles of shear stress. The extent of injury, as indicated by the fraction of cells with fragmented DNA, was three times higher for cyclic shear stress than for steady shear stress and may be related to the change in strain rate and/or cytoskeletal reorganization associated with cyclic stress. These findings may aid in understanding the mechanism by which neurons and neuron-like cells respond to cyclic shear stress and strain and lead to new treatments for disease or injury arising from the exposure of neurons to abnormal cyclic or repetitive stress and strain.

Molecular characterisation of a membrane-bound galactosyltransferase of plant cell wall matrix polysaccharide biosynthesis

Galactomannan biosynthesis in vitro is catalysed by membrane preparations from developing fenugreek seed endosperms. Two enzymes interact: a GDP-mannose dependent (1-->4)-beta-D-mannan synthase and a UDP-galactose dependent (1-->6)-alpha-D-galactosyltransferase. The statistical distribution of galactosyl substituents along the mannan backbone, and the degree of galactose substitution of the primary product of galactomannan biosynthesis appear to be regulated by the specificity of the galactosyltransferase. We now report the detergent solubilisation of the fenugreek galactosyltransferase with retention of activity, the identification on gels of a putative 51 kDa galactosyltransferase protein, and the isolation, cloning and sequencing of the corresponding cDNA. The solubilised galactosyltransferase has an absolute requirement for added acceptor substrates. Beta-(1-->4)-linked D-manno-oligosaccharides with chain lengths greater than or equal to 5 acted as acceptors, as did galactomannans of low to medium galactose-substitution. The putative galactosyltransferase cDNA encodes a 51282 Da protein, with a single transmembrane alpha helix near the N terminus. We have also confirmed the identity of the galactosyltransferase by inserting the cDNA in frame into the genome of the methylotrophic yeast Pichia pastoris under the control of an AOX promoter and the yeast alpha secretion factor and observing the secretion of galactomannan alpha-galactosyltransferase activity. Particularly high activities were observed when a truncated sequence, lacking the membrane-spanning helix, was expressed.

A small-angle neutron scattering study of gamma-crystallins near their isoelectric point

In this paper, a small-angle neutron scattering study of gammaII-crystallins near their isoelectric point is presented. The experiments were carried out using protein concentrations of 5.7-85.7 mg/ml at temperatures in the range 11 -60 degrees C. The experimental data were analyzed using an ellipsoidal model for intraparticle correlations and the mean spherical approximation for interparticle correlations. Our studies revealed that gammaII-crystallins have a thick hydration layer, which is possibly due to the special arrangement of polar and ionic groups on their surface. The temperature scan shows that, as a result of relatively strong attractive forces, clusters of two, three, or higher oligomers are present below 20 degrees C. Our results suggest that protein clusters, with a distinctive hydration layer, form a protein-rich phase that separates from a protein-lean phase as the temperature is decreased below some threshold value.

The use of postharvest treatments to extend storage life and to control postharvest wastage of honeydew melons (Cucumis melo L. var. inodorus Naud.) in cool storage

Three trials were undertaken to study storage conditions and handling procedures required to maximise the postharvest storage life of honeydew melons (Cucumis melo L. var. inodorus Naud.).Honeydew melons treated with chlorine (1000 mg/L), benomyl (250 mg/L) + guazatine (500 mg/L), shrink wrap (17 ym Cryovac XDR film), Semperfresh, wax, or combinations of these treatments were stored at 4 or 8�C, for 4 or 6 weeks. Benomyl plus guazatine reduced the development of storage rots associated with Alternaria and Fusarium spp. The use of shrink wrap and wax reduced water loss by melons but increased fungal infection in some cases. Shrink wrapping combined with the fungicide treatment effectively reduced the incidence of fungal breakdown in the storage period for up to 4 weeks. Wax coating with full strength Citruseal wax caused anaerobic tissue breakdown. Melons were affected by chilling injury at 4�C. Control of bacterial rots with benomyl + guazatine or with chlorine was variable. Semperfresh did not reduce the incidence of fungal breakdown or water loss from the melons. The results indicate that storage of honeydew melons for 4 weeks at 8�C by pretreating with fungicide is possible but the melons soften and rot after 6 weeks, making them unsaleable. Four weeks should be adequate to allow for sea freighting of honeydew melons to markets in South East Asia. Further research is required to determine the optimum storage temperature for honeydew melons.

Offset electrocardiographic electrode simulating a pulmonary nodule on radiographs

A recently developed type of electrocardiographic (ECG) monitoring electrode may simulate a pulmonary nodule on chest radiographs. The artifact results from the offset design of the electrode, which contrasts with the configuration of conventional electrodes. Awareness of this potential artifact is important to prevent misdiagnosis.

Psychophysiological factors in ventricular arrhythmias and sudden cardiac death

Plasma catecholamine levels were measured preceding programmed electrophysiological studies of patients who had survived a ventricular tachyarrhythmia episode. Psychological assessments of desire for control, locus of control and behavior pattern were obtained. Psychophysiological variables were analysed with respect to the severity of arrhythmias induced by the electrophysiological procedure. Analysis of data from 17 subjects showed desire for control was significantly higher in those with induced sustained arrhythmias than in those in which nonsustained arrhythmias were induced. No relationship was found between behavior pattern and arrhythmia severity or plasma catecholamine levels. There was a significant interaction between desire for control and behavior pattern with respect to epinephrine level. The findings indicate that psychological factors such as desire for control may be associated with potentially lethal arrhythmias and implicated in sudden cardiac death.

The release of insoluble antibiotics from collagen ocular inserts in vitro and their insertion into the conjunctival sac of cattle

The release rate of procaine penicillin, erythromycin and erythromycin estolate from soluble and insoluble collagen films was investigated in vitro to develop an ocular insert for the treatment of infectious bovine keratoconjunctivitis. The release rate and duration of release varied according to the selection of antibiotic and vehicle. The combination of erythromycin estolate and soluble collagen produced the most sustained drug-delivery system. However, due to the inappropriate physical properties of collagen and poor retention of ocular inserts, it was considered that the development of an antibiotic-impregnated collagen ocular insert requires further investigation.

Conversion from cyclosporine to azathioprine following heart transplantation

Eleven patients receiving cyclosporine were converted to azathioprine immunosuppression because of persistent creatinine elevation greater than 2 mg/dl 6 months or more following heart transplantation. During conversion, the maintenance steroid dose was doubled for 3 months then tapered to the preconversion dose. Pretransplant renal function in these converted patients was similar to that in a group of azathioprine patients and a group of nonconverted cyclosporine patients. One year following transplant, the nonconverted group had stable but impaired renal function (mean creatinine, 1.45 +/- 0.06 mg/dl; effective renal plasma flow, 407 +/- 39 ml/min; glomerular filtration rate, 68 +/- 8.8 ml/min). The converted patients had evidence of progressive renal dysfunction (mean creatinine, 2.65 +/- 0.19 mg/dl; effective renal plasma flow, 193 +/- 16 ml/min; glomerular filtration rate, 29 +/- 5.1 ml/min). Following conversion, renal function improved toward normal in all patients. There were three episodes of rejection that were successfully treated. An important number of infective and noninfective complications occurred following conversion during the period of steroid augmentation. There were two deaths during the follow-up period. Conversion can be undertaken with low risk of rejection, death, or both, but protocols that employ prolonged periods of steroid augmentation are associated with important morbidity.

Ocular inserts for application of drugs to bovine eyes--in vitro studies on gentamicin release from collagen inserts

Soluble collagen and insoluble collagen films were impregnated with gentamicin and investigated in vitro as vehicles for the delivery drugs. Succinylated collagen released significantly higher levels of antibiotic than the insoluble films, and maintained mean inhibitory concentrations (MIC) for Moraxella bovis for 24 h.

A national survey of the clinical features, treatment and importance of infectious bovine keratoconjunctivitis

A postal survey of cattle producers throughout Australia was conducted to obtain information concerning the occurrence, signs and treatment of infectious bovine keratocojunctivitis, animals breeds, animal numbers and types, environmental conditions under which the animals were kept and management routines and systems of the animals (Slatter et al 1982). The most common clinical signs reported were ocular discharge (43.9%), corneal opacity (9.9%), or both (46.1%). The majority of respondents (54.8%) indicated duration of infections of at least 3 weeks. The condition was predominantly unilateral (74.7%) but 22.3% of respondents reported an equal occurrence of the condition unilaterally and bilaterally. The most frequently used drugs were homidium bromide (26.7%), oxytetracycline hydrochloride (22.8%), chloramphenicol derivatives (13.7%) and penicillin derivatives (13.5%). However, described treatment regimes indicated that therapeutic levels of antibiotics would not be maintained in the eyes of treated animals. Producers considered that 75% of affected animals showed reduced rates of weight gain, and 64% indicated they were more difficult to handle. An approximate figure of +22,000,000 was determined for loss of national production due to the disease, based on producers' estimates. In addition, a further cost of +1,566,500 was estimated for the labour involved in current treatment regimes. Beef and dairy producers spent different amounts on medications and treated for different durations. The economic significance of the disease justifies further studies on production losses due to the disease and cost effective methods of treatment.

A national survey of the occurrence of infectious bovine keratoconjunctivitis

A national mail survey of 4880 beef and dairy producers was undertaken to record details of infectious bovine keratoconjunctivitis. One thousand four hundred and fifty eight (29.8%) questionnaires were returned. The survey confirmed the widespread nature of the disease with higher prevalence in the summer months, in calves and dairy cattle, and in Bos taurus breeds. The constant prevalence contrasts with the disease in New Zealand where it is increasing.

Pathogenesis of an unexpected sudden death: role of early cycle ventricular premature contractions

A 61 year old man who had been studied extensively died unexpectedly ("instantaneously") outside the hospital while wearing an electrocardiographic recorder. Death was caused by ventricular fibrillation, which was initiated by an early cycle ventricular premature contraction occurring in the vulnerable period of repolarization. Such early cycle ventricular premature contraction had been noted in recordings 4 years previously but had never been observed to encroach on the T wave until 5 minutes before death. In the intervening period, the patient had shown increasing evidence of myocardial ischemia and hypertrophy and congestive heart failure, which had been partly obscured by his concealment or denial of symptoms and refusal to change his pattern of activities. Autopsy revealed two old myocardial infarcts and pronounced left ventricular hypertrophy. There was advanced occlusive arteriosclerosis of the major coronary vessels with a recent thrombus in the right coronary artery.

Carbon Dioxide and Ethylene Control of Spore Germination in Onoclea sensibilis L

Regulation of spore germination in the fern Onoclea sensibilis L. was investigated by applying CO(2) alone and in combination with ethylene. Sterile spores were sown aseptically on Knops solution in loosely capped culture tubes, enclosed individually in 2-liter chambers, and grown under continuous white light. When maintained in enclosed containers with the ethylene-absorbent mercuric perchlorate and with atmospheres enriched up to 2% CO(2) (v/v), spores germinated without any inhibition. Higher levels of applied CO(2) were progressively inhibitory. Inhibition by CO(2) was reversible. When CO(2) was permitted to escape and spores were exposed subsequently to ambient laboratory air, recovery from inhibition occurred within 48 hours. Also, inhibition by CO(2) was specific, since the same degree of inhibition resulted regardless of whether spores were treated with exogenous CO(2) for 48, 72, or 96 hours. The effect on germination of 1 mul/l added ethylene depended upon the amount of applied CO(2). When containers of KOH were enclosed and ambient CO(2) was absorbed, inhibition of germination by 1 mul/l exogenous ethylene was 90%. When CO(2) was applied in concentrations from 0.25 to 1.0% (v/v), CO(2) increasingly antagonized the inhibitory action of 1 mul/l added ethylene. Thus, photoinduced germination of spores was regulated by competitively interacting levels of CO(2) and ethylene.

The release in vitro of vasopressin unaccompanied by the axoplasmic enzymes: lactic acid dehydrogenase and adenylate kinase

Lactic acid dehydrogenase (LDH) and adenylate kinase were shown by differential centrifugation to be mainly associated with the supernatant fraction of ox neurohypophyses. In vitro release of vasopressor activity, LDH and adenylate kinase from groups of rat neural hemilobes or slices of ox neurohypophyses was studied at rest and after stimulation with a high potassium concentration or after electrical stimulation. Although release of vasopressor activity increased considerably on stimulation, no significant change in the release of LDH or adenylate kinase could be detected. The findings are discussed in relation to the different hypotheses for the mechanism of release of vasopressin.