Neurosteroid modulation of synaptic and GABA-evoked currents in neurons from the rat medial preoptic nucleus

The effects of the neurosteroid 3alpha-hydroxy-5alpha-pregnane-20-one (allopregnanolone) on synaptic and GABA-evoked currents in acutely dissociated neurons from the medial preoptic nucleus of rat were investigated by perforated-patch recordings under voltage-clamp conditions. The effect of 2.0 microM allopregnanolone on GABA-evoked currents depended strongly on the GABA concentration: the currents evoked by 100 microM GABA were markedly depressed and the desensitization was faster, but the decay after GABA application was prolonged. In contrast, the currents evoked by 1.0 microM GABA were markedly potentiated, the activation was faster, a prominent desensitization was induced, and the decay after GABA application was prolonged. In the absence of externally applied GABA, 2.0 microM allopregnanolone induced a slow current that could be attributed to Cl-. Allopregnanolone did not significantly affect the amplitude of spontaneous tetrodotoxin-insensitive (miniature) synaptic currents (mIPSCs) originating from synaptic terminals releasing GABA onto the dissociated neurons. However, the mIPSC decay phase was dramatically prolonged, with half-maximal effect at approximately 50 nM allopregnanolone. A qualitatively similar effect of allopregnanolone was seen when KCl was used to evoke synchronous GABA release. The frequency of mIPSCs was also affected, on average increased 3.5-fold, by 2.0 microM allopregnanolone, suggesting a presynaptic steroid action.

Retinoid binding proteins-expression patterns in the human placenta

The present study examined the expression and occurrence of different retinoid binding proteins in human first trimester and term placenta. At both stages, messenger RNA for the serum transport vehicle for retinol, retinol-binding protein (RBP), was detected only in decidual cells of the basal plate. In contrast, immunoreactive RBP (irRBP) was present in syncytiotrophoblast, core mesenchyme and lumen of vessels in placental villi and in mesenchyme and decidual cells of the basal plate. In villi of term placentae, however, staining for irRBP was lost in syncytiotrophoblasts and villous core mesenchyme. A putative placental RBP-receptor, approx 60-65kDa, was detected in the villous syncytiotrophoblast of both stages investigated. Immunoreactivity for the cellular retinol binding protein type I (CRBP I), was found in villous stromal cells and in decidual cells of the basal plate in sections of first trimester and term placenta. These results may suggest that maternal RBP-retinol is transferred across the chorionic villi to the fetal/villous circulation and that villous absorption of the complex is mediated via a placental RBP-receptor. Moreover, binding and possibly also metabolism of retinol may occur in the CRBP I positive villous stromal cells and decidual cells of the basal plate. In the latter, release of placental RBP-retinol may also be anticipated.

Beta1 integrin promotes but is not essential for metastasis of ras-myc transformed fibroblasts

To investigate the role of beta1 integrin during tumor metastasis, we established a ras-myc transformed fibroblastoid cell line with a disrupted beta1 integrin gene on both alleles (GERM 11). Stable transfection of this cell line with an expression vector encoding beta1A integrin resulted in beta1A integrin-expressing sublines. Tumors were induced by subcutaneous injection of GERM 11 cells and 3 independent beta1 integrin expressing sublines (GERM 116, 1A10, 2F2) into syngeneic mice. After 10 days tumors were surgically removed. While average weights of GERM 11 and GERM 116 tumors were similar, tumors induced by the high expressing clones 1A10 and 2F2 were markedly smaller, suggesting an inverse correlation of tumor growth and beta1 integrin expression. The metastasis potential of all three beta1 integrin-expressing GERM 11 sublines tested was significantly higher than that of the beta1-deficient GERM 11 cells. GERM 116 tumors led in all animals to severe metastasis in lung and liver, while GERM 11 tumors induced only a few metastatic foci in the lung. Stroma of both tumors contained nidogen and high amounts of tenascin C, but only a few very low levels of fibronectin, laminin-1, and collagen type I. Beta1 integrin, therefore, increases but is not essential for metastasis of ras-myc transformed fibroblasts.

Alterations of tumour cells, stroma and apoptosis in rat prostatic adenocarcinoma following treatment with histamine, interleukin-2 and irradiation

The present study was designed to determine whether IL-2 and histamine alone, or in combination could modulate the effects of irradiation on Dunning (R3327) rat adenocarcinomas at the cellular level. Copenhagen x Fisher rats carrying bilateral tumours in the flank were used. When the tumours had a median volume of 150 mm3, one group of rats was treated with histamine alone (4 mgkg-1 subcutaneously on week days), another group with interleukin-2 (IL-2) alone (425 IU kg-1 continuous infusion) and a third group with both histamine and IL-2 during 6 weeks. Irradiation was given one week after the onset of treatment with histamine and/or IL-2, with a linear accelerator 6 MV, in a dose of 6 Gy/day for 3 days to the tumour of one side, while the other side served as control. Morphometric analyses of the amount of cystic structures, volume density for tumour epithelium, stroma and acinar lumina, the number of activated macrophages and natural killer cells (NK-cells) and in situ detection of apoptotic cells was carried out 5 weeks after the irradiation, when the experiment was ceased. The combination of IL-2 with histamine and irradiation significantly augmented the reduction of tumour cells (p < 0.002) and increased the number of apoptotic cells (p < 0.007) compared to irradiation alone. The number of cystic structures within tumour tissue increased in all tumours that received histamine, but was most pronounced in the three combination group. A strong negative correlation between the epithelial cells and the apoptotic index (rs = -0.61, p < 0.0001) and a strong positive correlation between the stroma and the apoptotic index (rs = 0.59, p < 0.001) was found. A prominent infiltration of activated macrophages was observed in the irradiated group. This infiltration was impaired by the drugs. The results suggested that the used three modality treatment could be of value in increasing the efficacy of local radiotherapy concomitantly with a most plausible effect on micrometastatic spread. The results also propose that volume measurements alone are not an optimal parameter when evaluating effects of new treatment modalities.

Relaxed versus activated stump muscles during casting for trans-tibial prostheses

In prosthetic practice, the question often arises as to whether the hand cast should be made from a contracted or from a non-contracted amputation stump. To elucidate this question, the authors have performed a study to quantify the volume difference between these 2 conditions, and to relate the differences to prosthetic fitting. Sixteen (16) trans-tibial amputees participated in the study. All of them were fitted with an ICEROSS silicone socket. Electromyographic studies, with electrodes attached to the anterior tibial and medial gastrocnemius muscles, were carried out to determine muscle contraction levels. Volume determinations were made with the CAPOD laser scanning system. Measurements were performed with and without the silicone liner on the stump. Without a silicone liner, the volume of the stump increased by 5.8% (SD=5.3) as the muscles contracted. This increase was statistically significant. With the liner donned the volume increased 3.5% (SD=3.3). This increase was also statistically significant. The volume of the prosthetic socket was also compared with the stump volume with a silicone liner on. For the relaxed stump, the difference was 1.8% (SD=10.1), and for the contracted stump -1.7% (SD=11.3). Neither difference was statistically significant. The importance of these volume changes and how they influence stiffness of the coupling between the stump and the socket are discussed. It is concluded, that the observed difference in volume between a contracted and a non-contracted stump are large enough to be considered by the prosthetist in his decision on how to make a hand cast.

Seven novel macrocyclic polypeptides from Viola arvensis

Seven novel macrocyclic polypeptides, designated as varv peptides B-H, have been isolated from the aerial parts of Viola arvensis. Their primary structures have been elucidated by automated Edman degradation and mass spectrometry. They all consist of 29 or 30 amino acid residues, covalently cyclized via the amide backbone and by three internal disulfide bridges. Their amino acid sequences are as follows: varv peptide B, cyclo-(TCFGGTCNTPGCSCDPWPMCSRNGLPVCGE); varv peptide C, cyclo-(TCVGGTCNTPGCSCSWPVCTRNGVPICGE); varv peptide D, cyclo-(TCVGGSCNTPGCSCSWPVCTRNGLPICGE); varv peptide E, cyclo-(TCVGGTCNTPGCSCSWPVCTRNGLPICGE); varv peptide F, cyclo-(TCTLGTCYTAGCSCSWPVCTRNGVPICGE); varv peptide G, cyclo-(TCFGGTCNTPGCSCDPWPVCSRNGVPVCGE); and varv peptide H, cyclo-(TCFGGTCNTPGCSCETWPVCSRNGLPVCGE). The varv peptides B-H exhibited high degrees of homology with the hitherto known macrocyclic peptides varv peptide A, kalata B1, violapeptide I, circulins A and B, and cyclopsychotride A.

Echovirus 5: infectious transcripts and complete nucleotide sequence from uncloned cDNA

Echovirus 5 (EV5) may be isolated from various neurological and exanthematic diseases. To determine the relationship of EV5 to other enteroviruses and for studies of its interactions with the target cell, the complete nucleotide sequence of EV5 was determined. Three overlapping fragments, collectively representing the complete genome, were amplified with RT-PCR and sequenced. Analysis of the EV5 sequence revealed a typical enterovirus-like organization of the genome. To verify that the cDNA generated sequence was derived from infectious viruses, complete EV5 genomes were amplified in one amplicon by long distance PCR. Transfection of in vitro transcribed RNA from these amplicons into cell cultures resulted in replicating EV5. Comparison of the overall nucleotide and amino acid sequences demonstrates that EV5 can be regarded as a coxsackievirus B-like enterovirus. Variable sequences between EV5 and the well characterized coxsackievirus B3 (CVB3) are for the most part observed for amino acid residues that correspond to exposed sequences in the CVB3 capsid. This observation indicates that the reported EV5 strain recently diverged from group B coxsackieviruses.

Effects of ongoing smoking on the development of radiation-induced pneumonitis in breast cancer and oesophagus cancer patients

PURPOSE

To investigate the influence of smoking on the development of radiation-induced pneumonitis in patients treated for breast and oesophagus cancer.

MATERIALS AND METHODS

This is a retrospective study on 405 females diagnosed with primary unilateral breast cancer stages 1 and 2 and 201 oesophagus carcinoma patients. The possibilities in Sweden to obtain detailed information from different medical records were used to collect data on smoking habits, radiation treatment and spontaneously reported pneumonitis. Radiation-induced pneumonitis was defined as a combination of roentgenographic infiltrate in the lung field involving an irradiated area on the chest X-ray and clinical symptoms such as non-productive cough and dyspnoea.

RESULTS

Six breast cancer patients had spontaneously reported pneumonitis. Five of them were non-smokers (P = 0.182) and the other was a former smoker. Eight of the oesophagus cancer patients had spontaneously reported radiation-induced clinical pneumonitis and they were all non-smokers (P = 0.022), except one, who was a pipe smoker. None of the patients who were cigarette smokers were recorded as developing clinical pneumonitis after irradiation.

CONCLUSION

These data could support the previous clinical observations and experimental studies that smoking depresses the frequency of radiation-induced pneumonitis. The present study as well as earlier observations could justify further studies concerning the possibility of an interaction of smoking with cancer treatment, both from the view of therapeutic failures and reduced adverse effects.

Mouse myoblasts can fuse and form a normal sarcomere in the absence of beta1 integrin expression

Antibody perturbation experiments suggested that migration, terminal differentiation and fusion of myoblasts are dependent on beta1 integrin expression. In addition, several studies have postulated that beta1 integrins have a role in the formation of sarcomeres. In the present report we have analysed skeletal myogenesis in wild-type/beta1-null chimeric mice and beta1-null embryoid bodies. Trunk and limbs of beta1-null chimeric mice contained muscle tissue composed of normal and beta1-null myoblasts indicating that all myotomic sublineages can form, migrate to their peripheral targets and fuse in the absence of beta1 integrin expression. Pure populations of beta1-null myoblasts and satellite cells isolated from beta1-null chimeric embryos and chimeric newborn mice, respectively, were able to differentiate in vitro and to fuse into multinucleated myotubes. Quantitative and qualitative comparisons between normal and beta1-null myoblasts revealed no apparent difference in their capacity to terminally differentiate and fuse. Furthermore, beta1-null myotubes developed sarcomeres which were indistinguishable from wild-type controls. When normal and beta1-null ES cells were differentiated into embryoid bodies, they contained fully differentiated myotubes with normal sarcomeres and normal deposition of costameric components. However, formation of beta1-null myotubes was delayed and was less efficient in beta1-null embryoid bodies than in wild-type controls. High expression of alphav integrin subunit at the tips of normal as well as beta1-null myotubes indicated that the lack of beta1 integrins did not result in a significant redistribution of alphav-containing receptors.

Comparison of mortality from peptic ulcer bleed between patients with or without peptic ulcer antecedents

We studied mortality related to peptic ulcer bleed in a well defined cohort of patients in the month after the episode of peptic ulcer bleed. Our objective was to assess the contribution of peptic ulcer antecedents and other predictive factors on the risk of dying. The study cohort comprised 1,020 patients hospitalized for an episode of peptic ulcer bleed between January 1991 and March 1994 and identified in the General Practice Research Database in the United Kingdom. Six hundred twenty-three patients had no prior episode of peptic ulcer disease, and 384 had peptic ulcer antecedents; for 13 patients, information was not available. Forty-five patients died (mortality rate = 4.4 per 100 person-months; 95% confidence interval = 3.3-5.9) within 1 month of the peptic ulcer bleed. Patients with no peptic ulcer antecedent faced a greater risk of dying than patients with antecedents (relative risk = 3.0; 95% confidence interval = 1.2-7.1). Elderly patients, those undergoing surgery, and current users of acid-suppressing drugs or nonsteroidal antiinflammatory drugs all had an increased mortality risk. Patients presenting with their first-ever episode of peptic ulcer bleed have a higher case fatality rate than those with previous episodes of peptic ulcer.

Mutational analysis of the potential phosphorylation sites in the cytoplasmic domain of integrin beta1A. Requirement for threonines 788–789 in receptor activation

To investigate the role of the potential phosphorylation sites in the cytoplasmic domain of integrin beta1A, point mutated variants of the protein were stably expressed in the beta1-deficient cell line GD25. Mutants T777A, Y783F, S785A, and Y795F were fully active in promoting cell adhesion, de novo formation of focal contacts, formation of fibronectin fibrils, and activation of focal adhesion kinase. Thus, phosphorylation of these residues is not required for several basic functions of integrin beta1A. On the other hand, the TT788-9AA mutant, was defective in mediating cell attachment and did not contribute to fibronectin fibril formation. The conformation of the extracellular domain was shifted towards an inactive state as measured by binding of the monoclonal antibody 9EG7. Antibody induced clustering of beta1ATT788-9AA demonstrated that the mutant cytoplasmic part was functional in mediating activation of focal adhesion kinase. Therefore, we conclude that threonines 788–789, which are conserved among most integrin beta subunits, are of critical importance for integrin function due to effects on the extracellular conformation of the receptor.

The response of Dunning R3327 prostatic adenocarcinoma to IL-2, histamine and radiation

A syngeneic, androgen-sensitive Dunning R3327 rat prostatic adenocarcinoma was transplanted bilaterally in the flanks of male Copenhagen Fisher rats. Approximately 3 months after implantation, when the tumours had a median volume of 150 mm3, one group of rats was treated with histamine alone (4 mg kg(-1) subcutaneously on week days), another group with human recombinant interleukin 2 (IL-2) alone (425 IU kg(-1) continuous infusion) and a third group with both histamine and IL-2 during 6 weeks. Tumours on one flank were irradiated (6 Gy once daily for 3 days to a total dose of 18 Gy) beginning 1 week after the onset of treatment with histamine and/or IL-2. The contralateral tumour served as the intra-animal control. The tumour volumes were determined weekly. The growth curves showed that all three drug treatments were effective in delaying growth, but when used individually did not cause tumour shrinkage. Radiation was the most effective single agent, but when used alone the shrinkage did not occur until 2 weeks after irradiation. When combined with the drugs, more rapid and extensive growth delay and/or shrinkage was seen. The growth curves showed clear differences between the different treatments. The combination of the three agents was the most effective of all. The most striking difference between radiation alone and radiation plus biotherapy was the time at which a tumour response was detectable. Thus, active biotherapy alone and especially in a combination with histamine and radiotherapy warrants further investigation as a potential therapeutic approach to prostate cancer.

Identification of beta1C-2, a novel variant of the integrin beta1 subunit generated by utilization of an alternative splice acceptor site in exon C

A new splice variant of the human integrin subunit beta1 has been identified and designated beta1C-2. It differs from the previously reported beta1C (in this report designated beta1C-1) by 18 nucleotides, and is generated by splicing from exon 6 to an alternative splice acceptor site within exon C, causing an in-frame deletion of six amino acids of the cytoplasmic region of beta1C-1. The beta1C-2 mRNA is present in several human cell lines and tissues at low levels, similarly to beta1C-1. In peripheral T-lymphocytes, beta1C-2 is the selectively expressed isoform. Neither beta1C-1 nor beta1C-2 mRNA could be detected in mouse tissues, and Southern hybridization of a mouse genomic beta1 clone with a human exon-C-specific probe failed to identify a corresponding mouse exon. The antisense orientation of exon C is highly homologous to an Alu element. Since Alu elements are restricted to primates, the beta1C-1 and beta1C-2 variants of the integrin subunit beta1 are specific for these species. The protein coded for by the beta1C-2 cDNA can be expressed and localized to the surface of beta1 deficient mouse cells. However, while stable transformed clones expressing high levels of the beta1A were commonly found, the beta1C-1 and beta1C-2 expressing clones expressed barely detectable amounts of the beta1 protein. Hence, high levels of beta1C-2 may be incompatible with cell proliferation, as previously suggested for beta1C-1.

Heterogeneous presynaptic Ca2+ channel types triggering GABA release onto medial preoptic neurons from rat

1. Voltage-dependent Ca2+ channels triggering GABA release onto neurons from the medial preoptic nucleus of rat were investigated. Acutely dissociated neurons with adherent functional synaptic terminals were investigated by tight-seal whole-cell recordings from the postsynaptic cells. 2. Spontaneous current events similar to miniature postsynaptic currents were recorded. They were blocked by bicuculline (100 microM), showed a roughly unimodal amplitude distribution and a reversal potential consistent with a Cl- current, and were therefore attributed to GABAA receptors activated by synaptically released GABA. 3. Application of 140 mM KCl, expected to depolarize presynaptic terminals, evoked currents that were ascribed to a more massive release of GABA. The KCl-induced synaptic currents were abolished in Ca2+-free solutions and showed a roughly hyperbolic relation to external Ca2+ concentration with half-saturation at 0.15 mM. They further depended on the concentration of applied KCl in a way expected for high-threshold Ca2+ channels. 4. The KCl-evoked synaptic currents were completely blocked by 200 microM Cd2+, but only partially blocked by 200 microM Ni2+. The KCl-evoked synaptic currents were insensitive to the L-type Ca2+ channel blocker nifedipine (10 microM). However, the synaptic currents were sensitive to either 1 microM omega-conotoxin GVIA, 25 nM omega-agatoxin IVA or 1 microM omega-conotoxin MVIIC. 6. It was concluded that, in many presynaptic terminals, the Ca2+ influx triggering GABA release onto medial preoptic neurons is mainly mediated by one predominant type of high- threshold Ca2+ channel that may be either of N-, P- or Q-type. 7. It was further concluded that terminals with similar predominant channel types often were clustered on the same postsynaptic cell.

Calcium spikes and calcium currents in neurons from the medial preoptic nucleus of rat

Ca2+ spikes, their contribution to firing patterns, and the underlying Ca2+ currents in neurons of the medial preoptic nucleus of rat were investigated by tight-seal whole-cell recordings in a slice preparation. Two different types of spikes were recorded: Low-threshold spikes were generated from membrane potentials <-75 mV. High-threshold spikes were recorded when K+ currents were reduced, and were readily evoked from membrane potentials near -40 mV. Both types of spikes were blocked by substitution of Co2+ for Ca2+ in the external medium, but were insensitive to 2.0 microM TTX. Under voltage-clamp conditions, two main types of Ca2+ currents were characterized: low-threshold currents that activated at membrane potentials >-60 mV, and high-threshold currents that activated at potentials >-30 mV. The low-threshold current and the low-threshold spike were more sensitive to block by external Ni2+ than to block by Cd2+, whereas the high-threshold current and the high-threshold spike were more sensitive to block by external Cd2+ than to block by Ni2+. Significant fractions of the high-threshold currents were blocked by 10 microM nifedipine, 1.0 microM omega-conotoxin GVIA, 50 nM omega-agatoxin IVA and 1.0 microM omega-conotoxin MVIIC, suggesting the presence of L-, N-, P- and Q-type Ca2+ channels. There were also a high-threshold current component insensitive to the above mentioned toxins. It is proposed that the low-threshold current serves as a trigger for short bursts of fast spikes from hyperpolarized levels, whereas the high-threshold current is involved in the Cd2+-sensitive burst firing seen in relatively depolarized neurons.

Fractionation Protocol for the Isolation of Polypeptides from Plant Biomass

A fractionation protocol for the isolation of a highly purified polypeptide fraction from plant biomass is described. The procedure dereplicates ubiquitous substance classes known to interfere with bioassays often used in natural product-based drug discovery programs. The protocol involves pre-extraction with dichloromethane, extraction with ethanol (50%), removal of tannins with polyamide, removal of low-molecular-weight components with size-exclusion chromatography over Sephadex G-10, and final removal of salts and polysaccharides with solid-phase extraction using reversed-phase cartridges. The method has been applied to the aerial parts of Viola arvensis, resulting in the isolation of a peptide fraction that on further separation yielded a novel 29-residue macrocyclic polypeptide named varv peptide A, cyclo(-TCVGGTCNTPGCSCSWPVCTRNGLPVCGE-).

Interaction between 3 alpha-hydroxy-5 alpha-pregnan-20-one and carbachol in the control of neuronal excitability in hippocampal slices of female rats in defined phases of the oestrus

The effects of 3 alpha-hydroxy-5 alpha-pregnan-20-one (allopregnanolone) and carbachol on CA1 and dentate gyrus action potentials were studied in hippocampus slices in premature, follicular and luteal phase rats. A 0.5 nL droplet of allopregnanolone (12.5 mumol L-1), carbachol (5 mumol L-1) or a mixed solution of 12.5 mumol L-1 allopregnanolone and 5 mumol L-1 carbachol was applied locally onto the stratum oriens-pyramidale or granular layer. The amplitude of CA1 population spike (POPSP) was reduced by allopregnanolone (-38 +/- 3%) and carbachol (-21 +/- 4%) in the luteal phase slices. The mixture of allopregnanolone and carbachol doubled this inhibition (-77 +/- 6%). The inhibition caused by allopregnanolone and the mixture of allopregnanolone and carbachol in CA1 was significantly larger in the luteal phase than in the follicular phase (P = 0.02 and 0.0002). In the granular layer of the dentate gyrus, these inhibitions showed no significant difference between the phases. Neither in CA1 nor in the dentate gyrus did the carbachol inhibition differ between the phases. Perfusion with 5-10 mumol L-1 carbachol caused an increasing inhibition of the POPSP during the first few minutes. Thereafter the inhibition gradually diminished and was replaced by a facilitation. The local allopregnanolone inhibition was enhanced by simultaneous carbachol perfusion. Picrotoxin (100 mumol L-1) substantially reduced the allopregnanolone but not the carbachol inhibition. Atropine (10 mumol L-1) blocked the carbachol response, but not the allopregnanolone inhibition. Perfusion with a mixed solution of picrotoxin and atropine reduced, but did not block, the inhibition caused by local application of allopregnanolone or by the mixture of allopregnanolone and carbachol. Our data suggest that neuroprogestine modulators of the GABAA-receptor-mediated inhibition may play a significant role in the control of the cholinergic excitation in the hippocampus.

Accuracy and precision of volumetric determinations using two commercial CAD systems for prosthetics: a technical note

The aim of this study was to evaluate the validity and reliability of volume determinations using the commercially available Seattle ShapeMaker CAD/CAM system for production of prosthetic sockets and to compare it with the commercially available CAPOD system. We used three types of reference objects for volumetric determinations: steel tubes, plaster of Paris casts, and residual limb models. Three different sizes were examined for each type of object. Volume measurements with the two CAD/CAM systems were compared with measurements obtained by water filling, water immersion, or mathematical calculation (tubes only). We found an inconsistent systematic error of less than 3.1% for ShapeMaker and no systematic error for CAPOD. Random errors, represented by the coefficient of variation, were below 1.3% for the ShapeMaker and, in most cases, below 0.4% for the CAPOD. Theoretical changes in volume of 2.6% and 0.8% are possible to detect with these CAD/CAM systems. In our opinion, both systems have sufficient precision for routine clinical use in prosthetics and orthotics. However, in our study, the ShapeMaker committed larger random and systematic errors than CAPOD. This means that, according to our study, CAPOD offers the best possibility to determine and detect small changes in residual limb volume as a function of time.

Chromosomal abnormalities in low grade chondrosarcoma and a review of the literature

In this study, cytogenetic analysis of two low-grade chondrosarcomas revealed relatively simple chromosomal complements with structural rearrangements involving chromosomes 1, 6, and 12 [46,XY,add(16)(q24)[3]/46,XY,t(1;20)(q21;q11),t(6;17)(q23;q23)[3]/46,XY, t(4;14)(q12;q24),t(5;6)(q12;p21) [2] and 45,XY,t(12;16)(q13;q24),-14[17]/44,idem,add(4)(p16),-17,[2] respectively]. Previously published reports of chondrosarcoma have revealed structural abnormalities of chromosomes 1, 6, 9, 12, and 15 as common. Also, a correlation between the simplicity or complexity of the abnormalities seen and histologic grade has been suggested. The findings of the current study support these earlier observations.

Currents evoked by GABA and glycine in acutely dissociated neurons from the rat medial preoptic nucleus

The responses of acutely dissociated medial preoptic neurons to application of GABA, and glycine were studied using the perforated-patch whole-cell recording technique under voltage-clamp conditions. GABA, at a concentration of 1 mM, evoked outward currents in all cells (n = 33) when studied at potentials positive to -80 mV. The I-V relation was roughly linear. The currents evoked by GABA were partially blocked by 25-75 microM picrotoxin and were also partially or completely blocked by 100-200 microM bicuculline. Glycine, at a concentration of 1 mM, did also evoke outward currents in all cells (n = 12) when studied at potentials positive to -75 mV. The I-V relation was roughly linear. The currents evoked by glycine were largely blocked by 1 microM strychnine. In conclusion, the present work demonstrates that neurons from the medial preoptic nucleus of rat directly respond to the inhibitory transmitters GABA and glycine with currents that can be attributed to GABAA receptors and glycine receptors respectively.

Risk factors for cardiovascular disease during the period 1985-1995 in Göteborg, Sweden. The GOT-MONICA Project

AIMS

To report levels of cardiovascular risk factors in 1985, 1990 and 1995 in three population samples in Göteborg, Sweden, and to compare with previous population risk factor levels.

POPULATION

The study was performed within the framework of the WHO MONICA Project which compares risk factor levels as well as the incidence of coronary heart disease and stroke in 38 populations.

METHODS

Three random samples of men and women aged 25-34, 35-44, 45-54 and 55-64 comprising 152-218 subjects in each age group who responded to the invitation for screening procedures which included questionnaires, physical and laboratory investigations in 1985, 1990 and 1995.

RESULTS

More men than women had smoked, except for those aged 35-44 where there was no difference between men and women. The proportion of men who had smoked decreased strongly between the first and third investigations (P < 0.0001), particularly amongst the younger age-groups, with a similar tendency amongst women. In the 25-44-years age group there was a tendency towards more women than men to be smokers in 1995. Snuff was used by 27% and 19% of men aged 25-34 and 35-44 years, respectively, in 1995. Up to 5% of women used snuff; higher in the younger age groups. More young men than women reported regular physical activity during leisure time with a tendency towards an increase from 1985 to 1995. The proportion of men reporting psychological stress varied little over the study period, but women aged 25-34 reported increased stress from 1985 to 1995. Body weight increased whereas height remained stable and consequently body mass index increased in men and women (P = 0.0001). Similarly, waist:hip ratio (measured in 1990 and 1995 only) also increased (P = 0.0001). Mean systolic and diastolic blood pressure increased with age and there was also a small increase between 1985 and 1995. Systolic blood pressure increased by a mean of 1.24 mmHg per 5-year period independent of sex and age (P = 0.0001). Antihypertensive treatment increased with age, but was stable between 1985 and 1995. Serum total and LDL cholesterol concentrations increased with age, and there was a nonsignificant tendency also to higher HDL cholesterol concentrations at older ages. Serum total cholesterol concentration declined between 1985 and 1995, and HDL cholesterol declined significantly between 1985 and 1995 in all age groups for men and women only when all age groups were analysed together. Similar to total cholesterol, levels of LDL cholesterol declined between 1985 and 1995 for all ages. Serum triglyceride levels increased for men and women between 1985 and 1995.

Management of the univentricular connection: are we improving?

OBJECTIVE

To assess the impact of the bidirectional cavopulmonary shunt, total cavopulmonary connection, and baffle fenestration on outcome of the Fontan operation in our unit.

METHOD

We reviewed 123 bidirectional cavopulmonary shunts and 264 Fontan operations performed from 1980 to 1995. Analysis of pulmonary artery size (right and left main and lower lobe branches) before and after bidirectional cavopulmonary shunt was performed. Outcome of the Fontan operation was analysed in various time periods to assess the effect of prior bidirectional cavopulmonary shunt, use of the lateral tunnel, and fenestration.

RESULTS

Operative risk for the bidirectional cavopulmonary shunt was 4% (CI = 2-10%) with a survival of 89% (CI = 83-95%) at 36 months. Probability of conversion to Fontan operation at 36 months was 49% (CI = 38-61%). Pulmonary artery size (Nakata and lower lobe indices) fell after bidirectional cavopulmonary shunt (P = 0.0006). Fontan risk dropped from 8.5% (1980-1987) to 1.8% (1988-1995) (P = 0.02), coinciding with the use of the bidirectional cavopulmonary shunt. There was no further risk reduction after introduction of the lateral tunnel and baffle fenestration, although these comparisons are limited by relatively small numbers. Duration of hospital stay related to pleural effusions was lowest for patients with a fenestrated lateral tunnel operation (P < 0.05).

CONCLUSION

The bidirectional cavopulmonary shunt is a suboptimal stimulus for pulmonary artery enlargement, but may reduce the risk of Fontan operation in selected children. Fenestrated lateral tunnel operations have reduced the duration of postoperative pleural effusions.

Glutamate-evoked currents in acutely dissociated neurons from the rat medial preoptic nucleus

Membrane currents evoked by glutamate were investigated in acutely dissociated neurons from the medial preoptic nucleus (MPN) of rat. Rapid application of glutamate induced a fast current component in all neurons studied. In addition, in > 50% of the neurons, a slow current component was elicited. The fast and the slow current components were selectively blocked by the AMPA-receptor antagonist NBQX and by the NMDA-receptor channel blocker MK-801, respectively. Rapid application of AMPA induced, in all neurons tested, currents with properties similar to the fast component of the glutamate-evoked currents whereas rapid application of NMDA induced, in approximately 75% of the neurons, currents similar to the slow component of the glutamate-evoked currents. The NMDA-evoked currents showed a marked outward rectification that was attributed to a potential-dependent block by extracellular Mg2+. The NMDA-evoked currents also required the presence of extracellular glycine in the micromolar range. In conclusion, the results show that MPN neurons respond to glutamate with currents that can be attributed to activation of ionotropic glutamate receptors of the AMPA-receptor type as well as of the NMDA-receptor type.

Retinoid binding proteins in mouse yolk sac and chorio-allantoic placentas

In the adult, as well as in the embryo, a number of specific extra- and intracellular binding proteins such as the plasma retinol binding protein (RBP), the cellular retinol binding protein type I (CRBP I), and also the cellular receptors for RBP are thought to regulate transport and metabolism of retinol (vitamin A). Since the regulation of materno-fetal transport of vitamin A is not well understood, we examined the localization of these proteins during the development of the mouse chorio-allantoic and yolk sac placentas. The labyrinthine region of the chorio-allantoic placenta, where exchange of substances can occur between the maternal and fetal circulations, did not contain RBP (mRNA or protein) or antigen(s) similar to the bovine RBP-receptor p63, whereas the visceral endoderm of the yolk sac placenta, the second site for materno-fetal transport, did. Furthermore, only the endodermal cells of the visceral yolk sac appeared to strongly accumulate radiolabelled retinoids. The cellular retinol binding protein (CRBP I) was detected both in the trophoblast layer of the placental labyrinth closest to the fetal endothelium (layer III), and in the visceral endoderm of the yolk sac. Together, these findings suggest that the yolk sac placenta mediates retinol transfer to the embryo/fetus throughout the entire gestation. The chorio-allantoic placenta, on the other hand, does not appear to have this capacity, while the presence of CRBP I does suggest a retinol-metabolizing capability.

Amplification and cloning of complete enterovirus genomes by long distance PCR

A method for amplification and cloning of complete enterovirus cDNA genomes is described. Viral RNA was reverse transcribed using an optimized protocol and a reverse transcriptase with reduced RNase H activity. Amplicons corresponding to complete genomes of 14 prototype strains of group B coxsackieviruses and echoviruses were amplified using oligonucleotide primers derived from the Coxsackievirus B3 genomic sequence of the 5' and 3' ends and a mixture of thermostable DNA polymerases. Coxsackievirus B2 amplicon was then cloned and the terminal sequences of the insert were determined. Lipofection of individual clones resulted in productive. Coxsackievirus B2 infection. The method described makes it possible to obtain large amounts of complete enterovirus cDNAs and simplifies the construction of infectious full-length cDNA clones. Successful amplification of all enterovirus prototype strains tested emphasizes the general use of the method described, which provides a rapid and efficient alternative to traditional cloning strategies.

Cell surface expression of two major yeast allergens in the Pityrosporum genus

BACKGROUND

We have previously identified two major allergens of Pityrosporum orbiculare and characterized these as 37 kDa and 67 kDa proteins.

OBJECTIVE

In the present study we have investigated the presence and subcellular location of the 37 kDa and 67 kDa allergen components in various members of the genus Pityrosporum as well as in Candida albicans, Candida parapsilosis and Saccharomyces cerevisiae.

METHODS

To detect both cell surface and intracellular expression of the allergens, flow cytometry and confocal laser scanning microscopy (CLSM) were used. The cells were stained with indirect immunofluorescent (IIF) or alkaline phosphatase anti-alkaline phosphatase (APAAP) methods using mouse monoclonal antibodies (MoAbs).

RESULTS

Ninety-five per cent of the P. orbiculare (P. ovale) cells cultured for 4 days showed cell surface-binding of the anti-37 kDa MoAb and 88% of the cells bound the anti-67 kDa MoAb when analysed with IIF and flow cytometry. It was found that the members of the genus Pityrosporum (Malassezia), P. pachydermatis and M. sympodialis, expressed the 37 kDa and 67 kDa allergens to a similar extent as did P. orbiculare. Less than 5% of the cells of the genus Candida and S. cerevisiae showed positive staining with the MoAbs. The CLSM revealed that the 37 kDa and the 67 kDa components were located to the cell wall and could not be detected inside the acetone fixed and APAAP stained yeast cells of the genus Pityrosporum. When the yeast cells were cultured for more than 4 days the expression of both allergens decreased significantly.

CONCLUSION

All three members of the genus Pityrosporum express the 37 kDa and 67 kDa major allergens on the cell surface, whereas these proteins could virtually not be detected in the Candida genus and S. cerevisiae.

Structural basis for differential receptor binding of cholera and Escherichia coli heat-labile toxins: influence of heterologous amino acid substitutions in the cholera B-subunit

The closely related B-subunits of cholera toxin (CTB) and Escherichia coli heat-labile enterotoxin (LTB) both bind strongly to GM1 ganglioside receptors but LTB can also bind to additional glycolipids and glycoproteins. A number of mutant CT B-subunits were generated by substituting CTB amino acids with those at the corresponding positions in LTB. These were used to investigate the influence of specific residues on receptor-binding specificity. A mutated CTB protein containing the first 25 residues of LTB in combination with LTB residues at positions 94 and 95, bound to the same extent as native LTB to both delipidized rabbit intestinal cell membranes, complex glycosphingolipids (polyglycosylceramides) and neolactotetraosylceramide, but not to non-GM1 intestinal glycosphingolipids. In contrast, when LTB amino acid substitutions in the 1-25 region were combined with those in the 75-83 region, a binding as strong as that of LTB to intestinal glycosphingolipids was observed. In addition, a mutant LTB with a single Gly-33-->Asp substitution that completely lacked affinity for both GM1 and non-GM1 glycosphingolipids could still bind to receptors in the intestinal cell membranes and to polyglycosylceramides. We conclude that the extra, non-GM1 receptors for LTB consist of both sialylated and non-sialylated glycoconjugates, and that the binding to either class of receptors is influenced by different amino acid residues within the protein.

Coronary heart disease attack rate, incidence and mortality 1975-1994 in Göteborg, Sweden

MATERIAL AND METHODS

Data from the Göteborg myocardial infarction register were used to investigate trends in attack rate, incidence of non-fatal myocardial infarction and mortality from coronary heart disease in persons aged 64 and below during the period 1975-1994.

RESULTS

Myocardial infarction was defined according to strict criteria which remained the same throughout the study period. Attack rate and incidence were 3-5 times higher among men than women. The ratio of recurrent infarcts out of all attacks increased with increasing age and was 14%, 20% and 24% for men aged 35-44, 45-54, and 55-64, respectively. Corresponding rates for women were 8%, 14%, and 22%, respectively. Both attack rate and incidence decreased significantly by 2.1-3.9% per year during the study period for most age groups. The 28-day fatality rate (hospitalized as well as non-hospitalized cases) tended to decline, but significantly so only in the oldest men. The same was true for 28-day fatality among hospitalized patients. The majority of all coronary heart disease deaths occurred outside hospital in people unaware they had coronary heart disease. Mortality from coronary heart disease decreased by 2.0-6.8% per year during the study period. In-hospital treatment of myocardial infarction with intravenous beta-blockers followed by oral treatment, nitroglycerin and thrombolytics increased during the study period. Coronary surgery and angioplasty were used in less than 5% of patients during the study period, but increased substantially in 1994.

CONCLUSION

Coronary heart disease and mortality in ages below 65 years are now decreasing in Sweden. Decreasing short-term mortality is almost certainly due to more efficient treatment in hospital, but as the majority of coronary heart disease deaths occur outside hospital and in people unaware they have coronary heart disease, primary prevention is still very important.

Fibronectin-integrin interactions

Fibronectin is recognized by at least ten cell surface receptors of the integrin family. Most cell types in the body can adhere to fibronectin via these receptors, and thereby fibronectin becomes involved in many different biological processes. Three areas related to fibronectin and its receptors which have developed rapidly during the last few years are summarized in this review: the mechanisms of interactions between fibronectin and integrins, fibronectin polymerization, and in vivo functions of the proteins as studied by gene targeting in mice.

Fibronectin exposes different domains after adsorption to a heparinized and an unheparinized poly(vinyl chloride) surface

The adsorption of fibronectin to poly(vinyl chloride) catheters with end-point attached (EPA) heparin and tridodecylmethylammonium chloride-heparinized poly(vinyl chloride) was compared to that of unheparinized poly(vinyl chloride) using antibodies directed against four different domains of the protein. After perfusion of human plasma on the EPA-heparinized surface, the exposure of the N-terminal 29-kD fragment increased during the first 5 h of perfusion. Also, the exposure of the 30-kD gelatin-binding and 65-kD cell-binding fragments increased with time, but at a lower level. On the unheparinized catheter, low levels of antibodies bound to the different domains, and the binding showed little variation during the 5 h of plasma perfusion, indicating that the fibronectin molecule does not change configuration to a significant extent on this surface after the initial adsorption. When the EPA-heparinized surface was preabsorbed with human fibrinogen before incubation with fibronectin, significantly less of the 29-kD (fibrin-binding) domain was exposed, and the 30-kD domain was not exposed. Exposure of the 31- and 65-kD domains increased after preadsorption of fibrinogen to the surface. Since fibronectin has heparin-binding domains, it adsorbs differently to a heparinized versus an unheparinized surface. This will influence subsequent binding of other proteins to the surface, as well as potential binding of microbes. The use of antibodies to defined domains of the fibronectin molecule provides a powerful tool in studies of configurational changes of fibronectin after adsorption to different surfaces.

Fifteen-year survival in prostate cancer. A prospective, population-based study in Sweden

OBJECTIVE

To describe the natural history of initially untreated early-stage prostate cancer. A key secondary objective was to calculate long-term survival rates by stage, grade, and age at diagnosis.

DESIGN

Prospective cohort study.

SETTING

Population-based in 1 county of Sweden, without screening for prostate cancer.

PATIENTS

A group of 642 patients with prostate cancer of any stage, consecutively diagnosed between 1977 and 1984 at a mean age of 72 years with complete follow-up to 1994.

MAIN OUTCOME MEASURES

Proportion of patients who died from prostate cancer, and 15-year survival (with 95% confidence interval [CI]), corrected for causes of death other than prostate cancer.

RESULTS

In the entire cohort, prostate cancer accounted for 201 (37%) of all 541 deaths. Among 300 patients with a diagnosis of localized disease (T0-T2), 33 (11%) died of prostate cancer. In this group, the corrected 15-year survival rate was similar in 223 patients with deferred treatment (81%; 95% CI, 72%-89%) and in 77 who received initial treatment (81%; 95% CI, 67%-95%). The corrected 15-year survival was 57% (95% CI, 45%-68%) in 183 patients with locally advanced cancer (T3-T4) and 6% (95% CI, 0%-12%) in those 159 who had distant metastases at the time of diagnosis.

CONCLUSION

Patients with localized prostate cancer have a favorable outlook following watchful waiting, and the number of deaths potentially avoidable by radical initial treatment is limited. Without reliable prognostic indicators, an aggressive approach to all patients with early disease would entail substantial overtreatment. In contrast, patients with locally advanced or metastatic disease need trials of aggressive therapy to improve their poor prognosis.

Mouse polymorphonuclear granulocyte binding to extracellular matrix molecules involves beta 1 integrins

The mechanism of adhesion of purified mouse polymorphonuclear granulocytes (PMN) to extracellular matrix proteins characteristic of basement membranes and the interstitium has been investigated and compared with the adhesion of a mouse progranulocytic cell line, 32DC13, and a mouse monocytic cell line, WEHI 78/24. All three cell types bound specifically to fibronectin and vitronectin to different degrees under different cellular activation states. 32DC13 bound to fibronectin and vitronectin strongly, and this binding increased upon cellular activation with phorbol 12-myristate-13-acetate (PMA) but not with formyl-Met-Leu-Phe. Only 32DC13 showed significant binding to laminin-1. By contrast, WEHI 78/24 and PMN bound only fibronectin and vitronectin; this binding was weak and was altered only marginally upon activation with PMA. In the case of WEHI 78/24, a slight increase in adhesion both to fibronectin and to vitronectin was observed after cellular activation with PMA, while PMN adhesion to both substrates was slightly reduced. The mechanism of binding to fibronectin and vitronectin was similar in the three cell types. The integrin alpha5 beta1 mediated fibronectin adhesion, demonstrating for the first time the existence of a functionally active beta1 integrin on mouse PMN. Vitronectin binding was mediated by alpha(v) beta3, as demonstrated by the ability of alpha(v)-specific cyclic L-Arg-L-Gly-L-Asp-D-Phe-L-Val (RGDfV) peptide (EMD66203), and anti-beta3 antibody to inhibit cell adhesion. 32DC13 adhesion to laminin-1 was via the alpha6 beta1 integrin. None of the three cell types tested bound to the basement membrane proteins collagen type IV and perlecan, or to the interstitial stromal constituents tenascin, collagen types I, V and VI. Interestingly, perlecan and collagen type IV were found to repel all three cell types. The relative inability of PMN, WEHI 78/24, and 32DC13 to bind to extracellular matrix proteins characteristic of basement membranes and their ability to bind inflammatory markers of the interstitium is discussed with respect to leukocyte extravasation processes.

Spontaneous signalling in small central neurons: mechanisms and roles of spike-amplitude and spike-interval fluctuations

Spontaneous brain activity is essential for normal brain function. We are studying spontaneous activity in hippocampus at several complexity levels: at the microscopic level by analyzing the role of ion channels, at the mesoscopic level by analyzing the neuronal impulse activity, and at the macroscopic level by computational studies of mean electric fields of cortical network models. We have focused on the role of a subset of hippocampal neurons in the rat--neurons of small size (diameter < 10 microns). The analysis of spontaneous impulse trains in these neurons, both isolated and in slices, show (i) that impulses vary in amplitude, the magnitude depending on the input signal, suggesting that the amplitude variability may play a role in the information processing of the brain, and (ii) that single ion channel events can trigger neuronal impulses, suggesting that these neurons can function as cellular random generators. The possible role of random generators are investigated by simulating spontaneous activity in a cortical network model, based on a simplified description of the architecture of the CA1 area of hippocampus. The simulations show that such random generators can induce synchronous oscillations in cortical networks. These findings highlight the role of microfluctuations for the global macroactivity of the brain, and stress the importance of the study of channel kinetics for brain physiology.

Isolation and characterization of a trisulfide variant of recombinant human growth hormone formed during expression in Escherichia coli

A new variant of human growth hormone was recently found [Pavlu, B. & Gellerfors, P. (1993) Bioseparation 3, 257-265]. We report here the identification and the structural determination of this variant. The variant, which is formed during the expression of human growth hormone in Escherichia coli, was found to be more hydrophobic than rhGH as judged by its prolonged elution time by hydrophobic interaction chromatography. The rhGH hydrophobic variant (rhGH-HV) was isolated and subjected to trypsin digestion and RP-HPLC analysis, resulting in an altered retention time of one single tryptic peptide as compared to the corresponding fragment of rhGH. This tryptic peptide constitutes the C-terminus (aa 179-191) of hGH and contains one of the two disulfide bridges in hGH, viz. Cys182-Cys189. Amino acid sequences and composition analyses of the tryptic peptide from rhGH-HV (Tv18-19) and the corresponding tryptic peptide from rhGH (T18+19) were identical. Electrospray mass spectrometry (ES MS) of Tv18+19 isolated from rhGH-HV revealed a monoisotopic mass increase of 32.7, as compared to T18+19 from rhGH. A synthetic Tv18+19 peptide having a trisulfide bridge between Cys182 and Cys189 showed identical fragment in ES/MS compared to Tv18+19 isolated from rhGH-HV, i.e. m/z 617.7 and 682.9. These fragments are formed through a unique cleavage in the trisulfide (Cys182-SSS-Cys189) bridge not found in the corresponding T18+19 disulfide peptide. Furthermore, the synthetic Tv18+19 co-eluted in RP-HPLC with Tv18+19 isolated from rhGH-HV. Two-dimensional NMR spectroscopy of the synthetic T18+19 and Tv18+19 peptides were performed. Using these data all protons were assigned. The major chemical shift changes (delta delta > 0.05 ppm) observed were for the beta-protons of Cys182 and Cys189 in Tv18+19 as compared to T18+19. CD spectroscopy data were also in agreement with the above results. Based on these physico-chemical data rhGH-HV has been structurally defined as a trisulfide variant of rhGH. The receptor binding properties of rhGH-HV was studied by a biosensor device, BIAcore. The binding capacity of rhGH-HV was similar to rhGH with a binding stoichiometry to the rhGHBP of 1:1.6 and 1:1.5, respectively, indicating that the trisulfide modification did not affect its receptor binding properties.

Potential-dependent block of human delayed rectifier K+ channels by internal Na+

The delayed rectifier K+ currents in differentiated human SH-SY5Y neuroblastoma cells were characterized with tight-seal recording techniques. Activation and inactivation parameters were measured. At high positive potentials, the current showed a marked rectification, causing a region of negative slope conductance in the current vs. potential curve. The rectification depended markedly on the pipette Na+ concentration. Without Na+, no rectification was observed, whereas with high Na+ (20-60 mM), a marked rectification was always observed. Tail current measurements showed a fast ( < 400 microseconds) block of K+ currents in the presence of internal Na+. With 60 mM Na+ in the pipette 8% of the K+ current was blocked at 0 mV, 27% at +20 mV, and 82% at +100 mV. Similar degrees of block were often seen with 30 mM Na+ in the pipette. The submembrane Na+ concentration in intact cells was estimated, on the basis of the reversal of Na+ current, to be approximately 15 mM. Single-channel K+ currents, in the cell-attached configuration, showed a conductance of approximately 20 pS at 40-60 mV above rest but showed rectification at high potentials.

Characterization of lymphocyte fibronectin

In vitro cultured "activated" peripheral blood lymphocytes and T-cell lines synthesized a high-molecular-weight gelatin binding molecule (MW 500 kDa), whereas resting lymphocytes showed poor or negligible synthesis of the same component. Concanavalin A-mediated anchorage of the lymphocytes to a substratum potentiated synthesis of the high-molecular-weight molecule. Western blotting of the gelatin-binding lymphocyte molecule demonstrated reactivity with antibodies specific for human fibronectin. Furthermore, immunocytochemistry showed reactivity of anti-fibronectin antibodies with T-lymphocytes at the single-cell level. The lymphocyte-derived fibronectin was preferentially cell associated and relatively small amounts were present in the culture medium. RT-PCR of total RNA from CD4+ T-cells and the lymphoid T-cell line MOLT-4 showed that the most abundant species of fibronectin mRNA lacked the entire III CS exon encoding the alpha 4 beta 1 binding region LDV. Amplification of the III CS region from other T-cell lines revealed that these cells expressed several fibronectin mRNA isoforms most of which were lacking the LDV coding sequence. In conclusion, synthesis of fibronectin is demonstrated to occur in T-lymphocytes and to be regulated by signals which activate the cells.

Beta 1 integrin-dependent and -independent polymerization of fibronectin

The mouse cell line GD25, which lacks expression of the beta 1 family of integrin heterodimers due to disruption of the beta 1 integrin subunit gene, was used for expression of full-length cDNA coding for splice variant A of the mouse beta 1 integrin subunit. In a stably transformed clone (GD25-beta 1A), the expressed protein was found to form functional heterodimeric receptors together with the subunits alpha 3, alpha 5, and alpha 6. Both GD25 and GD25-beta 1A attached to fibronectin and formed focal contacts which contained alpha v beta 3, but no detectable alpha 5 beta 1A. The presence of GRGDS peptide allowed alpha 5 beta 1A to locate to focal contacts of GD25-beta 1A cultured on fibronectin, while the beta 1-null GD25 cells were unable to attach under these conditions. Affinity chromatography revealed that alpha 5 beta 1A and alpha v beta 3 could bind to a large cell-binding fragment of fibronectin. alpha 5 beta 1A strongly promoted polymerization of fibronectin into a fibrillar network on top of the cells. Whereas little alpha v beta 3 was colocalized with the fibronectin fibrils in GD25-beta 1A cells, this integrin was able to support fibronectin fibril polymerization in GD25 cells. However, the alpha v beta 3-induced polymerization was less efficient and occurred mainly in dense cultures of the GD25 cells. Thus, while both alpha 5 beta 1A and alpha v beta 3 are able to support adhesion to fibronectin, alpha v beta 3 dominates in the formation of focal contacts, and alpha 5 beta 1A has a prime function in fibronectin matrix assembly. This is the first report on fibronectin matrix assembly in the absence of beta 1 integrins.

Chondrocyte and chondrosarcoma cell integrins with affinity for collagen type II and their response to mechanical stress

Mechanical stress is an important regulator of chondrocyte functions but the mechanisms by which chondrocytes sense mechanical signals are unknown. Receptors for matrix molecules are likely involved in the mechanical signaling. In the first part of this study we identified integrins with affinity for the cartilage-specific collagen type II. We report that the collagen-binding integrins alpha 1 beta 1 and alpha 2 beta 1 isolated from bovine chondrocytes or human chondrosarcoma cells bound collagen type II as judged from affinity chromatography. The integrins alpha 3 beta 1 or alpha 9 beta 1 did not bind collagen type II-Sepharose. In the second part of the study we investigated the effect of mechanical stress on expression of matrix molecules and integrin subunits. Chondrocytes and chondrosarcoma cells, cultured on uncoated flexible silicone membranes in the presence of serum, were exposed to mechanical stress by the Flexercell system. Dynamic stimulation of chondrocytes for 3 h increased the mRNA expression of collagen type II and aggrecan as judged by Northern blotting, while the beta 1-integrin subunit was not changed. When chondrosarcoma cells were exposed to mechanical stimulation under the same conditions, mRNA expression of alpha 5 was found to increase while beta 1, alpha 2, and alpha v did not increase to significant levels. In another study the effect of mechanical stress on integrins was investigated when the cells were cultured on collagen type II-coated flex-dishes. Three hours of dynamic stress increased the mRNA expression of alpha 2-integrin subunit while the level of mRNA for integrin subunits beta 1, alpha 1, alpha 5, and alpha v showed no or small changes, indicating that matrix components may modulate the expression of integrins during mechanical stress.

Graded action potentials generated by neurons in rat hypothalamic slices

Preoptic neurons in rat hypothalamic slices were investigated with tight-seal whole-cell recording techniques. The main aim was to investigate the ability to generate graded, stimulus-dependent impulses. In response to rectangular current pulses, all cells generated impulses with an amplitude that to some degree depended on the stimulus strength. Stronger current steps induced impulses of larger amplitude. In 50% of the cells, a systematic variation of impulse amplitude of more than 10 mV (up to 40 mV) was recorded, implying a clear deviation from the 'all-or-nothing' principle. A clear variation in amplitude of spontaneous impulses was also recorded, in the whole-cell mode as well as from intact cells in the cell-attached mode.

Release of cytokines, polymorphonuclear elastase and terminal C5b-9 complement complex by infusion of wound drainage blood

25 patients undergoing total hip replacement surgery were studied in an investigation of release of cytokines (interleukin-1 beta, IL-1 beta; interleukin-6, IL-6; interleukin-8, IL-8; and tumor necrosis factor-alpha, TNF-alpha), PMN elastase and terminal C5b-9 complement complexes (TCC) at the time of collection and transfusion of autologous blood. 15 patients received wound blood that was washed and centrifuged before being transfused as an erythrocyte suspension. In this blood there were no elevations in the concentrations of cytokines, TNF-alpha, PMN elastase or TCC, and there was no increase in these variables in plasma after transfusion of wound blood. 10 patients received postoperatively-collected drainage blood. There were high amounts of cytokines, PMN elastase and TCC in this blood, and filtration of the collected drainage blood did not reduce the concentrations of these factors, except those of TCC. When the collected drainage blood was infused, elevated plasma concentrations of IL-6, IL-8 and PMN elastase were observed 1 and 60 minutes after completing the transfusion. No differences regarding blood pressure, oxygen saturation (SpO2), and hemoglobin concentration between the groups were recorded.

Protein kinase C phosphorylates two of the four known syndecan cytoplasmic domains in vitro

The transmembrane heparan sulfate proteoglycans of the syndecan family are implicated to participate in several cellular reactions which are dependent on protein kinase C. We have used an in vitro assay to assess whether any of the Peptides corresponding to the complete cytoplasmic domains of rat syndecans 1 through 4 were used as substrates for the enzyme. The syndecan-2 (fibroglycan) and syndecan-3 (N-syndecan) peptides were both found to be phosphorylated by protein kinase C with Kms of 15 +/- 3 microM and 85 +/- 25 microM, respectively, while the syndecan-1 and -4 peptides were not phosphorylated under the conditions used. The sites of in vitro phosphorylation for syndecans-2 and -3 were localized to ser-197 and ser-339, respectively. Thus, among 13 available sites (serines and threonines) in the four peptides, two were selectively modified by the enzyme. The specificity and the kinetics of the reactions indicate that the cytoplasmic domains of syndecan-2 and -3 are likely to be physiological substrates for protein kinase C.