Properties of the inward-rectifying Cl- channel in rat choroid plexus: regulation by intracellular messengers and inhibition by divalent cations

The properties of the inward-rectifying Cl- conductance in rat choroid plexus epithelial cells were investigated to allow comparisons to be made with ClC-2. All experiments were performed using the whole-cell configuration of the patch-clamp method. The conductance was transiently activated using an electrode solution which contained 375 nM catalytic subunit of protein kinase A (PKA). PKA failed to activate the conductance, however, when cells were pre-incubated with phorbol esters, which activate protein kinase C [1 microM phorbol 12-myristate 13-acetate (PMA) and 1 microM phorbol 12,13-dibutyrate (PDBu)]. Sustained activation of the conductance by PKA was observed in Ca2+-free conditions (5 mM BAPTA in the electrode solution), or when 100 nM calphostin C, a PKC inhibitor, was added to the electrode solution. The inward-rectifying Cl- conductance in choroid plexus is therefore similar to ClC-2 in that it is inhibited by PKC. The inward-rectifying conductance was blocked when Cd2+ (30 and 300 microM) and Zn2+ (1, 30 and 300 microM) were added to the bath solution. ClC-2 channels are also blocked by Zn2+ and Cd2+. The magnitude of the inward conductance was dependent on the concentration of ATP in the electrode solution. The conductance was not observed when ATP in the electrode was replaced with non-hydrolysable ATP analogues [adenosine 5'-O-(3-thiotriphosphate) (ATP[gamma-S]) and 5'-adenylylimidodiphosphate (AMP-PNP)), but it was supported by UTP and GTP. These data contrast with those of previous studies in which ClC-2 channels were activated in the absence of ATP. In conclusion, the inward-rectifying Cl- channel in rat choroid plexus shares some properties with ClC-2 (inhibition by PKC and block by divalent cations), but differs in that it depends on intracellular ATP.

An analysis of facial nerve function in irradiated and unirradiated facial nerve grafts

PURPOSE

The effect of high-dose radiation therapy on facial nerve grafts is controversial. Some authors believe radiotherapy is so detrimental to the outcome of facial nerve graft function that dynamic or static slings should be performed instead of facial nerve grafts in all patients who are to receive postoperative radiation therapy. Unfortunately, the facial function achieved with dynamic and static slings is almost always inferior to that after facial nerve grafts. In this retrospective study, we compared facial nerve function in irradiated and unirradiated nerve grafts. METHODS AND MATERIALS The medical records of 818 patients with neoplasms involving the parotid gland who received treatment between 1974 and 1997 were reviewed, of whom 66 underwent facial nerve grafting. Fourteen patients who died or had a recurrence less than a year after their facial nerve graft were excluded. The median follow-up for the remaining 52 patients was 10.6 years. Cable nerve grafts were performed in 50 patients and direct anastomoses of the facial nerve in two. Facial nerve function was scored by means of the House-Brackmann (H-B) facial grading system. Twenty-eight of the 52 patients received postoperative radiotherapy. The median time from nerve grafting to start of radiotherapy was 5.1 weeks. The median and mean doses of radiation were 6000 and 6033 cGy, respectively, for the irradiated grafts. One patient received preoperative radiotherapy to a total dose of 5000 cGy in 25 fractions and underwent surgery 1 month after the completion of radiotherapy. This patient was placed, by convention, in the irradiated facial nerve graft cohort.

RESULTS

Potential prognostic factors for facial nerve function such as age, gender, extent of surgery at the time of nerve grafting, preoperative facial nerve palsy, duration of preoperative palsy if present, or number of previous operations in the parotid bed were relatively well balanced between irradiated and unirradiated patients. However, the irradiated graft group had a greater proportion of patients with pathologic evidence of nerve invasion (p = 0.007) and unfavorable type of nerve graft (p = 0.04). Although the irradiated graft cohort had more potentially negative prognostic factors, there was no difference in functional outcome (H-B Grade III or IV) between irradiated and unirradiated graft patients. H-B Grades III, IV, V, and VI were the best postoperative facial nerve functions achieved in 35%, 39%, 13%, and 13% of patients, respectively. The patient with preoperative radiotherapy never recovered any facial nerve function (H-B Grade VI). Median time to best facial nerve function after surgery was longer in the irradiated patients (13.1 vs. 10.8 months), but this was not statistically significant (p = 0.10). Presence of preoperative facial nerve palsy (p = 0.005), duration of preoperative palsy (p = 0.003), and age greater than 60 years at the time of grafting (p = 0. 04) were all negative prognostic factors for achieving a functional facial nerve on univariate analysis. Analysis of age as a continuous variable (p = 0.12) and pathologic evidence of nerve invasion (p = 0. 1) revealed a trend toward negative prognostic factors. Gender, number of previous operations in the parotid bed, extent of surgery at the time of nerve grafting, and type of grafting procedure were not significant prognostic factors. Whether radiotherapy was delivered less than 6 weeks after nerve grafting or more than 6 weeks had no impact on achievement of a functional facial nerve.

CONCLUSION

Negative prognostic factors for achieving a functional facial nerve in our series include the presence of preoperative facial nerve palsy, duration of preoperative palsy, and age greater than 60 years. Radiotherapy was not a negative prognostic factor. Comparing irradiated and unirradiated grafts revealed no difference in best facial nerve function achieved, despite the presence of a greater proportion of negative prognostic factors in

Selective inhibition of glucose-stimulated beta-cell activity by an anion channel inhibitor

4,4'-Dithiocyanatostilbene-2,2'-disulfonic acid (DIDS), an inhibitor of the volume-sensitive anion channel, was used to investigate the role of this channel in the stimulation of rat pancreatic beta-cells by glucose and by tolbutamide. Glucose-stimulated electrical activity in beta-cells was markedly and reversibly inhibited by DIDS. The increase in cytosolic [Ca2+] and stimulated insulin release evoked by glucose were also inhibited by DIDS. In contrast to its inhibitory effect on glucose-induced beta-cell activity, DIDS had no effect on electrical activity, the rise in [Ca2+]i or insulin release induced by tolbutamide. DIDS failed to increase beta-cell input conductance, an index of whole-cell K(ATP) channel activity, or the rate of efflux of 86Rb+ from perifused islets, a measure of net K+ permeability. Furthermore, DIDS had no effect on intracellular pH or on regulatory volume increase following exposure of cells to hypertonic solutions, indicating that the effects of DIDS were not the result of inhibition of Cl- transport systems. It is suggested that the DIDS-induced repolarization is caused by inactivation of the volume-sensitive anion channel. The stimulation of beta-cell electrical and secretory activity by glucose, but not tolbutamide, may therefore involve activation of the anion channel.

Ongoing trials with matrix metalloproteinase inhibitors

Excessive or poorly regulated matrix metalloproteinase (MMP) activity has been implicated as a pathogenic factor in a range of diseases where the extracellular matrix is degraded or remodelled. Synthetic, potent, low molecular weight MMP inhibitors (MMPIs) have been developed and, over the past five years, these agents have begun clinical testing in patients with cancer, rheumatoid arthritis, osteoarthritis and acute macular degeneration. The past year has seen a number of disappointments with the halting of clinical trials of Ro 32-3555 in patients with rheumatoid arthritis and of BAY 12-9566 in patients with cancer. There have, however, been some successes with perhaps the clearest indication of efficacy being seen in the results of a Phase III trial of marimastat in patients with advanced gastric cancer. Clinical trials are continuing with marimastat and other MMPIs, including prinomastat, solimastat, BMS 275291, metastat and neovastat. Results from these trials are expected in the next two years and it is likely that clinical trials with MMPIs will begin in patients with other diseases where MMPs are believed to be involved, such as restenosis, cerebral haemorrhage and multiple sclerosis. Future research is likely to focus on the identification of specific MMP targets in different diseases, both in order to improve efficacy and to reduce the musculoskeletal side effect profile that has characterised several of the first generation oral MMPIs.

Vasopressin V1a receptor signaling in a rat choroid plexus cell line

A new cell line was derived from primary culture of rat choroid plexus (RCP) by immortalization with the TSOri minus adenovirus. The selected clone expressed vasopressin V1a receptors at a density of 64,000 sites per cell, and a K(d) of 7.2 nM. Addition of vasopressin to the RCP cells induced a transient calcium peak comparable to V1a receptor signalling in different expression systems. This [Ca(2+)](i) increase was dose-dependent with an EC(50) of 22 nM vasopressin. Similar [Ca(2+)](i) increase was elicited by addition of serotonin, angiotensin II, endothelin-1, and bradykinin. Heterologous desensitization of V1a receptor was observed in RCP cells exposed to the phorbol ester PMA or following stimulation of other receptors coupled to the phosphoinositide pathway. Positive immunolabelling with Factor VIII, Flt1 and CD 34 antibodies suggests that this new RCP cell line originated from endothelial cells of rat choroid plexus.

Therapeutic alliance: predicting continuance and success in group treatment for spouse abuse

This study examined the role of the therapeutic alliance between client and therapist on group treatment outcome in 70 husband-to-wife violent couples. Strength of husbands' alliance assessed at Session 1 was positively associated with treatment outcome, as measured by decreased husband-to-wife mild and severe psychological and physical aggression. Strength of wives' alliance was unrelated to treatment outcome. Finally, although alliance was related to treatment outcome, it was unrelated to treatment completion.

Origin of Threefold Periodicity in High-Resolution Transmission Electron Microscopy Images of Thin Film Cubic SiC

: High-resolution transmission electron microscopy (HRTEM) images of the [1-10] zone of cubic SiC layers grown by molecular beam epitaxy (MBE) often reveal regions of material exhibiting an unusual threefold periodicity. The same contrast was found in earlier works of Jepps and Page, who attributed this contrast in HRTEM images of polycrystalline SiC to the 9R-SiC polytype. In this report we demonstrate by HRTEM image simulations that the model of the 9R polytype and an alternative twinning model can fit qualitatively the experimental HRTEM images. However, by comparing the fast Fourier transform (FFT) patterns of the experiments and the simulations, as well as by using dark-field imaging, we show unambiguously that only the model of overlapping twinned 3C-SiC crystals fully agrees with the experiments.

Metastatic spinal cord compression in patients with colorectal cancer

BACKGROUND

A retrospective study was performed to examine the outcome of patients with colorectal cancer who had metastatic spinal cord compression (MSCC) and received radiation therapy (RT).

METHODS

Forty episodes of MSCC were treated with external beam RT in 34 patients with metastatic colorectal cancer. The median total dose was 3000 cGy (1800-4750 cGy), and the daily fraction size was 300 cGy (151-400 cGy). All patients were followed until death.

RESULTS

Median overall survival for the entire cohort was 4.1 months. Of 21 patients ambulatory before RT, 20 remained ambulatory after treatment, whereas only 2 of 9 patients who were nonambulatory regained full ambulatory status. Patients with rectal primary tumors had improved survival (median 7.9 months) compared with those who had colon primary tumors (2.7 months) (P = 0.002). Patients who received a total dose of more than 3000 cGy had a better survival (7 months) than those who received 3000 cGy or less (3.1 months) (P = 0.024). There was a trend for improved survival in patients fully ambulatory at diagnosis (P = 0.056) and after RT (P = 0.07). Unlike other primary sites in which approximately 70% of lesions are located in the thoracic spine, the location of epidural metastasis in colorectal primary tumors was most frequently in the lumbar spine (55% of lesions).

CONCLUSIONS

Prognostic features and outcomes for MSCC with primary colorectal cancer are similar to those for other primary sites. There is a suggestion that rectal primary tumors may be associated with an improved outcome compared with colon primary tumors. Patients who received more than 3000 cGy total dose had a longer survival than those who received lower total doses.

Allelochemicals released in soil following incorporation of rapeseed (Brassica napus) green manures

Plant-derived allelochemicals such as those produced by glucosinolate hydrolysis in Brassica napus, or rapeseed, are viable alternatives to synthetic compounds for the control of soil-borne plant pests. However, allelochemical production and residence times in field soils have not been determined. Soil samples were taken at 0-7.5 and 7.5-15 cm during a period of 3 weeks following plow-down of two winter rapeseed cultivars (Humus and Dwarf Essex). Soil samples were extracted with dichloromethane and analyzed using gas chromatography. Nine glucosinolate degradation products were identified-five isothiocyanates, three nitriles, and one oxazolidinethione. Maximum concentrations were observed 30 h after plow-down. Compounds derived from 2-phenylethyl glucosinolate, the principal glucosinolate in rapeseed roots, dominated the profile of degradation products. Shoot glucosinolates left few traces. This indicates that rapeseed roots may be a more important source of toxic fumigants than above-ground parts of the plant.

S-phase induction by interleukin-6 followed by chemotherapy in patients with chronic lymphocytic leukemia and non-Hodgkin's lymphoma

Interleukin-6 (IL-6) has in vitro demonstrated growth regulatory effects on tumor cells from patients with chronic lymphocytic leukemia (CLL) and lymphoma. The proliferation rate of these cells is usually very low and this is thought to be one of the reasons for the lack of a curative potential of cytostatic chemotherapy in CLL and low grade NHL. Recombinant human (rh) IL-6 might increase the in vivo proliferation rate leading to a higher sensitivity for chemotherapy. We tested this hypothesis by administering rhIL-6 to 9 CLL patients and 3 NHL patients in doses of 2.5 micrograms/kg, 5 micrograms/kg and 10 micrograms/kg s.c. daily for 5 days followed by CHOP chemotherapy on the last day of rhIL-6 injection. Six patients had two treatment cycles. The proportion of cells in S-phase was determined by the bromodeoxyuridine labeling index (LI). Three patients achieved a partial remission, one patient had progressive disease and the remaining patients demonstrated no change. Two patients, who received 10 micrograms/kg/day rhIL-6, demonstrated a significant increase in LI, one of these was first observed in the second treatment cycle. A significant decrease was seen in two patients receiving 2.5 micrograms/kg and 5 micrograms/kg respectively. Immunophenotypic assessment demonstrated that rhIL-6 increased the expression of CD20 in all CLL patients with a reversal after cessation of rhIL-6. We conclude that rhIL-6, in the dosage and schedule used in this study, did not increase the proportion of the cells in S-phase and that the growth stimulatory effects of rhIL-6 in CLL in vivo probably are insignificant. However, the role of rhIL-6 in CLL as inducer of increased CD20 expression prior to anti-CD20 antibody treatment remains to be determined.

Preclinical and clinical studies of MMP inhibitors in cancer

The role of matrix metalloproteinases in tumor angiogenesis and growth is now well recognized for models of both human and animal cancer. Clinical studies currently under way with the prototype matrix metalloproteinase inhibitor, marimastat, will establish whether inhibitors of these enzymes are of benefit in the treatment of different types of human cancer. On chronic therapy in humans, marimastat induces a reversible tendinitis that can also be detected in certain animal species. This paper compares the ability of broad-spectrum and various types of selective matrix metalloproteinase inhibitors to induce tendinitis and to exhibit anticancer effects in an animal cancer model. Under conditions in which both systemic exposure and inhibitor potency are controlled, selective inhibitors are less pro-tendinitic, but are weaker anticancer agents than broad-spectrum agents such as marimastat. The clinical relevance of these findings is discussed.

A pilot study of the safety and effects of the matrix metalloproteinase inhibitor marimastat in gastric cancer

The aim of this study was to evaluate the safety and tolerability of 4 weeks administration of marimastat, and to seek evidence of biological activity as observed by changes in the endoscopic appearance of the gastric tumours. 35 patients with advanced, inoperable gastric or gastro-oesophageal tumours were recruited. The dose of marimastat was reduced from the starting dose of 50 mg twice daily (6 patients) to 25 mg once daily (29 patients). 31 completed the 28 day study period. Marimastat was generally well tolerated, with the principal treatment-related toxicity being pain and stiffness of the musculoskeletal system. These symptoms occurred more frequently at the higher-dose, and increased to involve a total of 13 patients (37%) with longer-term treatment. The events were usually rapidly reversible on drug discontinuation. 3 patients receiving prolonged treatment experienced more severe symptoms, with the development of skin thickening and contractures in the hands. At endoscopy, 10 patients showed an increased fibrotic cover of the tumour, 8 had decreased haemorrhagic appearance, and in at least 2 cases where comparative tumour histology was assessable, there was evidence of increased stromal fibrotic tissue.

Matrix metalloproteinase inhibitors

Matrix metalloproteinases (MMPs) are a family of enzymes responsible for the breakdown of proteins of connective tissue. Through this action they play an important role in growth, development and tissue repair. Recent studies also suggest that MMPs are utilised in cancer, facilitating both local tumour invasion and metastasis. Levels of certain MMPs such as stromelysin-3 and gelatinase are elevated in tumour-associated stroma compared to non-involved tissue. A series of synthetic low molecular weight MMP inhibitors have been produced. Early inhibitors were based on the peptide structure of collagen, although more recently non-peptide inhibitors have also been developed. The inhibitors are selective for the MMP family and are active at low nanomolar concentrations. Experiments in models of breast cancer have shown that MMP inhibitors can significantly reduce the growth rate of both primary and secondary tumours, and can block the process of metastasis. Several MMP inhibitors have now started clinical trials in patients with advanced malignancy. Although not the optimum setting for a tumouristatic agent, early results suggest this approach may be effective in slowing tumour growth. Trials in the adjuvant setting will provide the most important test of these inhibitors and should determine their potential to complement existing cytoreductive treatments and prolong survival.

Clustering of cases of Mycobacterium fortuitum infection investigated by molecular typing

Organisms of the Mycobacterium fortuitum complex are recognised but uncommon causes of pulmonary disease, primary cutaneous disease and a wide spectrum of nosocomial infections. M fortuitum was isolated from 20 patients over a 15 month period, with an apparent clustering of isolates occurring from January to March 1994. The molecular epidemiology of this clustering was investigated using an arbitrary primer polymerase chain reaction method (AP-PCR). 21 isolates were studied, which yielded 13 distinct profiles. Multiple isolates from a single patient yielded identical profiles. All of seven isolates recovered during the six week period from January to March 1994 shared a common profile which was distinct from all other isolates, suggesting that a single strain was isolated from specimens from all seven patients. The source of this cluster is uncertain. We can find no epidemiological basis for an episode of cross-infection within the hospital environment, and it is assumed that contamination of the specimens during collection, transport or processing was responsible for the "pseudo-outbreak" of M fortuitum.

Regulation of a volume-sensitive anion channel in rat pancreatic beta-cells by intracellular adenine nucleotides

1. The patch-clamp technique in the whole-cell configuration was used to measure the effects of intracellular adenine nucleotides on activity of the volume-sensitive anion channel in single, isolated rat pancreatic beta-cells. 2. In the absence of intracellular nucleotides, swelling of cells with a hypertonic pipette solution failed to activate the conductance. Addition of ATP over the range 2-10 mM maintaining the same degree of hypertonicity caused a progressive activation of the conductance. An increase in ATP produced a similar activation of the conductance in non-swollen cells, albeit with reduced current amplitudes. 3. Activation of the conductance was also observed in the presence of ATPgammaS, adenylyl imidophosphate (AMP-PNP), ADP, diadenosine tetraphosphate and GTPgammaS. Neither ADP nor GDPbetaS inhibited activation of the conductance by ATP. 4. It is concluded that activity of the beta-cell volume-sensitive anion channel can be modulated by changes in intracellular concentrations of ATP within the physiological concentration range by a mechanism that does not require nucleotide hydrolysis. Activity of the channel does not appear to be modulated by a G protein-coupled mechanism.

Marimastat in recurrent colorectal cancer: exploratory evaluation of biological activity by measurement of carcinoembryonic antigen

Marimastat is a specific inhibitor of matrix metalloproteinases that has been shown to be effective in cancer models. A pilot, escalating-dose study of oral marimastat was performed in patients with recurrent colorectal cancer, in whom evaluation of serological response was made by measurement of carcinoembryonic antigen (CEA) levels. The study assessed the safety and tolerability of 4 weeks administration of marimastat, and determined a dose range producing detectable serological effects. Patients were recruited with a serum CEA level greater than 5 ng ml(-1), and rising by more than 25% over a 4-week screening period. Patients were treated for 28 days and entered into a continuation protocol if a serological response or clinical benefit was observed. Pharmacokinetic and safety data determined that groups of patients were recruited sequentially at 25 mg and 50 mg twice daily, and, thereafter, 10 mg twice daily, 10 mg once daily, 5 mg once daily and 20 mg once daily. A biological effect (BE) was defined as a CEA value on day 28 no greater than on day 0; a partial biological effect (PBE) was defined as a rise in CEA over the 28-day treatment period of less than 25%. Of 70 patients recruited, 63 completed the 28-day treatment period, and 55 were eligible for cancer antigen analysis. Examination of the dose-effect relationships provides evidence for a causal relationship between marimastat and biological effects: the proportion of patients with BE or PBE was higher with twice daily dosing (16 out of 25, 64%) than with once daily dosing (11 out of 30, 37%) (P = 0.043, chi2 test). Furthermore, the median rates of rise of CEA fell markedly during treatment compared with the screening period for patients receiving twice daily marimastat (P<0.0001), but not for patients receiving marimastat once daily (P = 0.25). Musculoskeletal adverse events emerged as the principal drug-related toxicity of marimastat, occurring in a dose- and time-dependent fashion. It was concluded that marimastat was associated with dose-dependent biological effects in cancer patients. The occurrence of musculoskeletal side-effects define 25 mg twice daily as the upper limit of the dose range for continuous use in further studies. Therefore, a dose range of 20 mg once daily to 25 mg twice daily seems appropriate for further studies, which should aim to demonstrate the efficacy of the drug in terms of conventional clinical end points and describe the long-term tolerability of this novel agent.

Clinical studies with matrix metalloproteinase inhibitors

Matrix metalloproteinases (MMPs) have been implicated in the invasive growth and spread of tumours. Potent and selective inhibitors of MMPs have been synthesized. These inhibitors can prevent tumour invasion in vitro and have suppressed tumour growth and metastasis in animal cancer models. Several MMP inhibitors have now reached clinical trials. Phase I studies indicate that the inhibitors can be given by mouth and that over the short term they are well tolerated. Longer, randomised studies in cancer patients are now underway.

Methylglyoxal causes swelling and activation of a volume-sensitive anion conductance in rat pancreatic beta-cells

Membrane potential and whole-cell current were studied in rat pancreatic beta-cells using the 'perforated patch' technique and cell volume measured by a video-imaging method. Exposure of beta-cells to the alpha-ketoaldehyde methylglyoxal (1 mM) resulted in depolarization and electrical activity. In cells voltage-clamped at -70 mV, this effect was accompanied by the development of inward current noise. In voltage-pulse experiments, methylglyoxal activated an outwardly rectifying conductance which was virtually identical to the volume-sensitive anion conductance previously described in these cells. Two inhibitors of this conductance, 4,4'-dithiocyanatostilbene-2,2'-disulfonic acid (DIDS) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), also inhibited the depolarization and inward current evoked by methylglyoxal. Methylglyoxal increased beta-cell volume to a relative value of 1.33 after 10 min with a gradual return towards basal levels following withdrawal of the alpha-ketoaldehyde. None of the effects of methylglyoxal was observed in response to t-butylglyoxal which, unlike methylglyoxal, is a poor substrate for the glyoxalase pathway. Methylglyoxal had no apparent effect on beta-cell K+ channel activity. It is suggested that the metabolism of methylglyoxal to D-lactate causes beta-cell swelling and activation of the volume-sensitive anion channel, leading to depolarization. These findings could be relevant to the stimulatory action of D-glucose, the metabolism of which generates significant quantities of L-lactate.

Assimilation in visibility: additional evidence

The present research tested the theory that a less visible target increases in similarity to a more visible simultaneous context, and that therefore the target increases in visibility. This assimilation-in-visibility theory was tested using context + targets that were either 3-line brackets or 2-line right angles, contexts and targets that were the component lines of these context + targets, with the target always the identical single top line. Experiments with a total of 204 participants indicated that the 3-line context + targets resulted in better context + target versus context discriminations than target versus background discriminations than did the 2-line context + targets. This was so for both over-all errors and misses but not false alarms. It is concluded that only the 3-line context + targets increased the visibility of the 1-line target. Additional analysis indicated that the 2-line contexts of the 3-line context + targets were more visible than all the 1-line stimuli. So, the 1-line target assimilated to a simultaneous more visible 2-line context and thereby increased in visibility, thus improving the context + target versus context discrimination. This support for the assimilation-in-visibility theory is of interest because assimilation and contrast in visibility may play a large role in perception.

Differing effects of endogenous and synthetic inhibitors of metalloproteinases on intestinal tumorigenesis

Matrix metalloproteinase (MMP) activity has been associated with tumor invasion and metastasis in many different tumor types, but recent studies also support a role for these enzymes in earlier stages of the tumor progression continuum. Specifically, the expression pattern of MMPs in benign human and mouse gastrointestinal tumors suggests that they may function in the development or growth of non-invasive tumors. To address the contribution of MMP activity to the development of intestinal adenomas, we administered the synthetic MMP inhibitor batimastat and expressed the tissue inhibitor of metalloproteinases-1 (TIMP-1) in the gastrointestinal tract of Min mice, which spontaneously develop pre-malignant small and large intestinal tumors. Batimastat administration resulted in a 48% decrease in the number of Min tumors. This reduction in tumor number is similar to that observed in mice lacking the metalloproteinase matrilysin, and demonstrates the therapeutic and chemopreventive potential of MMP inhibitors for pre-malignant intestinal tumors. In contrast, forced TIMP-1 expression in transgenic mice had no effect or, in one line, unexpectedly augmented Min tumor multiplicity by 32%. This observation supports an in vivo tumor-promoting activity of TIMP-1 that could be related to the growth stimulatory effects of TIMP that have been documented in vitro. Taken together, these 2 approaches of modulating MMP activity in Min mice support a critical function of MMPs in Min tumorigenesis, underscore the importance of an MMP/inhibitor balance in maintaining tissue homeostasis and demonstrate that endogenous MMP inhibitors can have complex effects in particular cellular contexts.

The results of radiotherapy for brainstem tumors

OBJECTIVE

This analysis was performed to examine the outcome of adult and pediatric patients with brainstem tumors.

METHODS AND MATERIALS

Forty patients with brainstem glioma were evaluated retrospectively. Included were 24 females and 16 males ranging in age from 3 to 81 years (median, 29.5 years). These patients were treated with various combinations of surgery, chemotherapy, and radiotherapy (RT). The length of follow-up in survivors ranged from 0.6 to 20 years (median: 3.2 years, mean: 6 years). Survival rates were calculated with the Kaplan Meier method and differences between survival curves were calculated using the log-rank test.

RESULTS

The overall 2 and 5-year survival rates were 44% and 34%, respectively. The median survival time was 19 months. The 5-year survival rate was 54% for patients with tumors outside the pons compared to 21% for those with tumors involving the pons (p = 0.04). The 5-year survival rate was 59% for patients with exophytic tumors as compared to 23% for those with intrinsic tumors (p = 0.05). Patients undergoing subtotal resection had a 5-year survival rate of 53% compared to 28% for those having only a biopsy or no surgical intervention (p = 0.04). None of the other potential prognostic or treatment related factors evaluated [patient age, tumor grade, tumor histology, radiotherapy parameters (including BID fractionation, 3-D treatment planning, or the use of doses > 55 Gy), or the administration of adjuvant chemotherapy] evaluated were associated with patient survival.

CONCLUSIONS

Brainstem gliomas generally occur in younger individuals. The survival rates were better for patients with exophytic tumors, those involving sites other than the pons, and tumors amenable to subtotal resection. Improvements in the outcome of patients with brainstem gliomas will require new therapeutic approaches.

Community-acquired pneumonia

This seminar reviews the aetiology, clinical presentation, approach to diagnosis, and management of immunocompetent adults with community-acquired pneumonia (CAP). Pneumonia is a common clinical entity, particularly among the elderly. A thorough understanding of the epidemiology and microbiology of CAP is essential for appropriate diagnosis and management. Although the microbiology of CAP has remained relatively stable over the last decade, there is new information on the incidence of atypical pathogens, particularly in patients not admitted to hospital, and new information on the incidence of pathogens in cases of severe CAP and in CAP in the elderly. Recent studies have provided new data on risk factors for mortality in CAP, which can assist the clinician in decisions about the need for hospital admission. The emergence of antimicrobial resistance in Streptococcus pneumoniae, the organism responsible for most cases of CAP, has greatly affected the approach to therapy, especially in those patients who are treated empirically. Guidelines for the therapy of CAP have been published by the American Thoracic Society, the British Thoracic Society, and, most recently, the Infectious Diseases Society of America. These guidelines differ in their emphasis on empirical versus pathogenic-specific management.

The role of calcium in the volume regulation of rat lacrimal acinar cells

Earlier studies have suggested a role for Ca2+ in regulatory volume decrease (RVD) in response to hypotonic stress through the activation of Ca2+-dependent ion channels (Kotera & Brown, 1993; Park et al., 1994). The involvement of Ca2+ in regulating cell volume in rat lacrimal acinar cells was therefore examined using a video-imaging technique to measure cell volume. The trivalent cation Gd3+ inhibited RVD, suggesting that Ca2+ entry is important and may be via stretch-activated cation channels. However, Fura-2 loaded cells did not show an increase in [Ca2+]i during exposure to hypotonic solutions. The absence of any changes in [Ca2+]i resulted from the buffering of cytosolic Ca2+ by Fura-2 during hypotonic shock and therefore inhibition of RVD. The intracellular Ca2+ chelator, BAPTA, also inhibited the RVD response to hypotonic shock. An increase in [Ca2+]i induced by either acetylcholine or ionomycin, was found to decrease cell volume under isotonic conditions in lacrimal acinar cells. Cell shrinkage was inhibited by tetraethylammonium ion, an inhibitor of Ca2+-activated K+ channels. On the basis of the presented data, we suggest an involvement of intracellular Ca2+ in controlling cell volume in lacrimal acinar cells.