Nitrogen-containing bisphosphonates inhibit the mevalonate pathway and prevent post-translational prenylation of GTP-binding proteins, including Ras

Bisphosphonates are currently the most important class of antiresorptive drugs used for the treatment of metabolic bone diseases. Although the molecular targets of bisphosphonates have not been identified, these compounds inhibit bone resorption by mechanisms that can lead to osteoclast apoptosis. Bisphosphonates also induce apoptosis in mouse J774 macrophages in vitro, probably by the same mechanisms that lead to osteoclast apoptosis. We have found that, in J774 macrophages, nitrogen-containing bisphosphonates (such as alendronate, ibandronate, and risedronate) inhibit post-translational modification (prenylation) of proteins, including the GTP-binding protein Ras, with farnesyl or geranylgeranyl isoprenoid groups. Clodronate did not inhibit protein prenylation. Mevastatin, an inhibitor of 3-hydroxy-3-methylglutatyl (HMG)-CoA reductase and hence the biosynthetic pathway required for the production of farnesyl pyrophosphate and geranylgeranyl pyrophosphate, also caused apoptosis in J774 macrophages and murine osteoclasts in vitro. Furthermore, alendronate-induced apoptosis, like mevastatin-induced apoptosis, could be suppressed in J774 cells by the addition of farnesyl pyrophosphate or geranylgeranyl pyrophosphate, while the effect of alendronate on osteoclast number and bone resorption in murine calvariae in vitro could be overcome by the addition of mevalonic acid. These observations suggest that nitrogen-containing bisphosphonate drugs cause apoptosis following inhibition of post-translational prenylation of proteins such as Ras. It is likely that these potent antiresorptive bisphosphonates also inhibit bone resorption by preventing protein prenylation in osteoclasts and that enzymes of the mevalonate pathway or prenyl protein transferases are the molecular targets of the nitrogen-containing bisphosphonates. Furthermore, the data support the view that clodronate acts by a different mechanism.

Physical exercise and psychological well being: a critical review

The relation between physical exercise and psychological health has increasingly come under the spotlight over recent years. While the message emanating from physiological research has extolled the general advantages of exercise in terms of physical health, the equivalent psychological literature has revealed a more complex relation. The paper outlines the research evidence, focusing on the relation between physical exercise and depression, anxiety, stress responsivity, mood state, self esteem, premenstrual syndrome, and body image. Consideration is also given to the phenomena of exercise addiction and withdrawal, and implications for exercise prescription are discussed.

Collagenase production by rheumatoid synovial cells: stimulation by a human lymphocyte factor

Human peripheral blood lymphocytes incubated in culture for 1 to 3 days at 37 degree C, but not at 4 degree C, release a soluble factor which can stimulate, up to 400-fold, collagenase production by isolated, adherent, rheumatoid synovial cells. Production of lymphocyte factor is enhanced by phytohemagglutinin or concanavalin A. By gel filtration the factor has an apparent molecular weight of about 12,000.

Role of pressure gradients and bulk flow in dynamics of vasogenic brain edema

The authors present the results of an investigation of the vasogenic type of brain edema using cold injury in cats as a model. Their findings indicate that bulk flow and not diffusion should be considered the main mechanism for the spread of edema through the white matter. This conclusion is based on: 1) comparison of the distances actually traveled by various substances during edema spread with those calculated theoretically for migration of the substances by diffusion; 2) coincidence in the speed of movement by two substances (sucrose and albumin) with widely different diffusion coefficients; 3) measurement of interstitial fluid pressure (IFP) at various distances from the lesion showing the presence of increased IFP in the lesion area and decreasing pressures along the edema pathway toward the normal tissue; and 4) the fact that spreading of edema can be significantly impeded by inducing before the cold lesion an intracellular type of brain edema that reduces the size of the extracellular space (ECS) and increases the resistance to flow of edema fluid. The pressure-volume curve of the brain ECS, as derived from determinations of IFP and tissue water content, indicates that initial steep slope in IFP probably represents the high resistance to fluid mobility through the small diameter extracellular channels and the counteracting resistance of the intermingled structures of brain parenchyma to be separated. Once the IFP exceeds these opposing forces, the ECS dilates, fluid mobility increases, and the edema front advances.

Distinct protein targets for signals acting at the c-fos serum response element

The c-fos serum response element (SRE) is a primary nuclear target for intracellular signal transduction pathways triggered by growth factors. It is the target for both protein kinase C (PKC)-dependent and -independent signals. Function of the SRE requires binding of a cellular protein, termed serum response factor (SRF). A second protein, p62TCF, recognizes the SRE-SRF complex to form a ternary complex. A mutated SRE that bound SRF but failed to form the ternary complex selectively lost response to PKC activators, but retained response to PKC-independent signals. Thus, two different signaling pathways act through discrete nuclear targets at the SRE. At least one of these pathways functions by recruitment of a pathway-specific accessory factor (p62TCF). These results offer a molecular mechanism to account for the biological specificity of signals that appear to act through common DNA sequence elements.

Isolation of an iron-binding compound from Pseudomonas aeruginosa

An iron-binding compound was isolated from ethyl acetate extracts of culture supernatant fluids of Pseudomonas aeruginosa and was purified by successive paper and thin-layer chromatographic procedures. The purified compound was characterized by UV, visible, infrared, and fluorescence spectroscopy. The compound possesses phenolic characteristics, with little or no similarity to dihydroxybenzoates and no indication of a hydroxamate group. P. aeruginosa synthesized the compound during active growth in culture media containing less than 5 X 10(-6) M added FeCl3. When added to iron-poor cultures of P. aeruginosa, the compound promoted the growth of the bacterium and also reversed growth inhibition by the iron chelator ethylenediamine-di-(o-hydroxyphenylacetic acid).

Identification of the acid/base catalyst in Agrobacterium faecalis beta-glucosidase by kinetic analysis of mutants

The catalytic mechanism of the retaining beta-glucosidase (Abg) from Agrobacterium faecalis involves a double-displacement process in which an alpha-glucosyl-enzyme intermediate is formed with general acid catalytic assistance and then hydrolyzed with general base assistance. Glu170 was identified as an important residue, possibly the acid/base catalyst, on the basis of sequence alignments. This glutamate is conserved in almost all enzymes in family 1 of glycoside hydrolases. Detailed pre-steady-state and steady-state kinetic analyses of the mutant E170G suggested very strongly that Glu170 is the acid/base catalyst. First, kcat values were invariant with pH over the range of 5.0-9.0. Secondly, rates of formation of the glycosyl-enzyme, calculated from kcat/Km and k2, were similar to those of wild-type enzyme for substrates not requiring protonic assistance but dramatically reduced for those needing acid catalysis. Thirdly, addition of azide as a competitive nucleophile increased kcat values 100-300-fold for substrates whose rate-limiting step is deglycosylation, yielding beta-glucosyl azide, but had no effect on the wild-type enzyme. Other anionic nucleophiles had similar, but less dramatic effects. Previous results [Gebler, J.C., et al. (1995) 34, 14547-14553] had indicated that Tyr298F is important for catalysis. The kinetic consequences of the mutations in the double mutant E170G-Y298F are additive, resulting in a 10(6)-fold reduction in kcat values and allowing the accumulation of a stable (t1/2 > 7 h) glucosyl-enzyme intermediate. Thus, Glu170 and Tyr298 function independently, and a possible role for Tyr298 in modulating the pKa of the catalytic nucleophile is proposed.

Factors determining outcome for breast-conserving irradiation with margin-directed dose escalation to the tumor bed

PURPOSE

A prospectively applied treatment policy for breast-conserving therapy used margin assessment as the exclusive guide to the intensity of therapy directed at the tumor-bearing quadrant.

METHODS AND MATERIALS

From 1982-1994, there were 509 treated Stage I and II breast carcinomas with a median follow-up of 72 months. For operational purposes, tumor excision margins were prospectively defined as: > 5 mm, 2.1-5 mm, > 0 < or = 2 mm, and positive. If a margin was assessed as < or = 2 mm or indeterminate, and it was deemed cosmetically feasible, a reexcision of the tumor bed would be performed. All patients received whole breast irradiation to 50-50.4 Gy. The following scheme for tumor bed boost irradiation as a function of final margin status (FMS) was observed: (a) Minimal risk = no tumor found on reexcision, no boost performed; (b) low risk = FMS > 5 mm, boost of 10 Gy; intermediate risk = FMS 2.1-5 mm, boost to 14 Gy; high risk = FMS < or = 2 mm or positive, boost to 20 Gy. Cases were analyzed for local failure (LF) with respect to histology (invasive ductal (IDC), IDC with associated DCIS (IDC/DCIS), invasive lobular (ILC)), age, tumor size, total excision volume, reexcision, total dose, tamoxifen therapy, and chemotherapy.

RESULTS

There were 19 breast recurrences for a Kaplan-Meier local failure rate for all cases at 5 and 10 years of 2.7% and 7.1%, respectively. Local failure in the first 4 years of follow-up was rare, with a mean annual incidence rate of 0.25% that rose to a mean of 1.1% in subsequent years. Univariate results of Cox proportional hazards regression survival models found positive FMS (p = 0.02), IDC/DCIS (p = 0.04) and age (0.0006) as significantly associated with local failure. In a multivariable model of FMS and IDC/DCIS, FMS retained significance (p = 0.01) but IDC/DCIS was borderline (p = 0.06). When FMS and age were included in a multivariable model, there was a significant interaction (p = 0.01) between the two variables. There was a significant increase in the relative risk of LF for age < or = 45 years (range 11.1-17.4), irrespective of FMS category. Although excellent overall control rates were achieved for patients > 45 years, for younger patients LF rates appeared to remain proportional to the relative closeness of the FMS, despite rigorous dose escalation.

CONCLUSIONS

Graded tumor-bed dose escalation in response to FMS results in an exceptionally low risk of "early" local recurrence within the first 5 years of follow-up. However, this strategy is unable to completely overcome the longer term adverse influence of young age and positive FMS.

Impairment of driving performance caused by sleep deprivation or alcohol: a comparative study

A study was conducted to assess the relative impact of partial sleep deprivation (restriction to 4 h sleep before testing) and full sleep deprivation (no sleep on the night before testing) on 2 h of simulated driving, compared with an alcohol treatment (mean blood alcohol content = 0.07%). Data were collected from the 64 male participants on the primary driving task, psychophysiology (0.1 Hz heart rate variability), and subjective self-assessment. The results revealed that the full sleep deprivation and alcohol group exhibited a safety-critical decline in lane-keeping performance. The partial sleep deprivation group exhibited only noncritical alterations in primary task performance. Both sleep-deprived groups were characterized by subjective discomfort and an awareness of reduced performance capability. These subjective symptoms were not perceived by the alcohol group. The findings are discussed with reference to the development of systems for the online diagnosis of driver fatigue. Potential applications of this research include the formulation of performance criteria to be encompassed within a driver impairment monitoring system.

Development of Sertoli cell junctional specializations and the distribution of the tight-junction-associated protein ZO-1 in the mouse testis

Basally located tight junctions between Sertoli cells in the postpubertal testis are the largest and most complex junctional complexes known. They form at puberty and are thought to be the major structural component of the "blood-testis" barrier. We have now examined the development of these structures in the immature mouse testis in conjunction with immunolocalization of the tight-junction-associated protein ZO-1 (zonula occludens 1). In testes from 5-day-old mice, tight junctional complexes are absent and ZO-1 is distributed generally over the apicolateral, but not basal, Sertoli cell membrane. As cytoskeletal and reticular elements characteristic of the mature junction are recruited to the developing junctions, between 7 and 14 days, ZO-1 becomes progressively restricted to tight junctional regions. Immunogold labeling of ZO-1 on Sertoli cell plasma membrane preparations revealed specific localization to the cytoplasmic surface of tight junctional regions. In the mature animal, ZO-1 is similarly associated with tight junctional complexes in the basal aspects of the epithelium. In addition, it is also localized to Sertoli cell ectoplasmic specializations adjacent to early elongating, but not late, spermatids just prior to sperm release. Although these structures are not tight junctions, they do have a similar cytoskeletal arrangement, suggesting that ZO-1 interacts with the submembrane cytoskeleton. These results show that, in the immature mouse testis, ZO-1 is present on the Sertoli cell plasma membrane in the absence of recognizable tight junctions. In the presence of tight junctions, however, ZO-1 is found only at the sites of junctional specializations associated with tight junctions and with elongating spermatids.

A randomised phase II study of sialyl-Tn and DETOX-B adjuvant with or without cyclophosphamide pretreatment for the active specific immunotherapy of breast cancer

Studies in animal models of mouse mammary carcinoma have shown that ovine submaxillary mucin, which carries multiple sialyl-Tn (STn) epitopes, is effective in stimulating an immune response and inhibiting tumour growth. In similar studies using carbohydrate antigens, pretreatment with low-dose cyclophosphamide has been shown to be important in modulating the immune response to antigen possibly by inhibiting suppresser T-cell activity. In a clinical trial assessing the efficacy and toxicity of synthetic STn, patients with metastatic breast cancer were randomised to receive 100 micrograms STn linked to keyhole limpet haemocyanin (KLH) with DETOX-B adjuvant given by subcutaneous injection at weeks 0, 2, 5 and 9 with or without low-dose cyclophosphamide (CTX, 300 mg m-2) pretreatment, 3 days before the start of immunotherapy. Patients with responding or stable disease after the first four injections were eligible to receive STn-KLH at 4 week intervals. The main toxicity noted was the development of subcutaneous granulomata at injection sites. Of 23 patients randomised, 18 received four injections, 5 patients having developed progressive disease during the initial 12 week period. Two minor responses were noted in the 18 patients who received four active specific immunotherapy (ASI) injections and a further five patients had stable disease. Six patients continued ASI at 4 week intervals and a partial response was noted in a patient who had previously had stable disease. All patients developed IgG and IgM responses to sialyl-Tn and levels of IgM antibodies were significantly higher in those patients who were pretreated with CTX. Measurable tumour responses have been recorded following ASI with STn-KLH plus DETOX and the immunomodulatory properties of low-dose CTX have been confirmed.

The value of breast lumpectomy margin assessment as a predictor of residual tumor burden

PURPOSE

Margin assessment is commonly used as a guide to the relative aggressiveness of therapy for breast conserving treatment (BCT), though its value as a predictor of the presence, type, or extent of residual tumor has not been conclusively studied. Controversy continues to exist as to what constitutes a margin that is "positive," "close," or "negative." We attempt to address these issues through an analysis of re-excision specimens.

PATIENTS AND METHODS

As part of an institutional prospective practice approach for BCT, 265 cases with AJCC Stage I/II carcinoma with an initial excision margin that was < or = 2 mm or indeterminate were subjected to re-excision. The probability of residual tumor (+RE) was evaluated with respect to tumor size, histopathologic subtype, relative closeness of the measured margin, the extent of margin positivity graded as focal, minimal, moderate, or extensive, and the extent of specimen processing as reflected in the number of cut sections per specimen volume (S:V ratio). The amount of residual tumor was graded as microscopic, small, medium, or large. The histopathologic subtype of tumor in the re-excision specimen was classified as having an invasive component (ICa) or pure DCIS (DCIS).

RESULTS

The primary excision margin was positive, > 0 < or = 1 mm, 1.1-2 mm, and indeterminate in 60%, 18%, 5%, and 17%, respectively. The predominant histopathologies in the initial excision specimens were invasive ductal (IDC) (50%) and tumors with an extensive intraductal component (EIC) (43%). The histopathology of the initial excision specimen was highly predictive of the histopathology of tumor found on re-excision, as residual DCIS was found in 60% of +RE specimens with initial histopathology of EIC compared to 26% for IDC (p = 0.001). Neither the extent of margin positivity nor the extent of tumor in the re-excision were significantly related to the initial histopathologic subtype; however, a +RE was seen in 59% of EIC, 43% of IDC, and 32% of invasive lobular ILC cases (p = 0.01). The extent of margin positivity was significantly related to the size of the tumor such that tumor size < or = 20 mm was associated with a greater probability of focal or minimal margin involvement. Positive margins graded as focal, minimal, moderate/extensive were associated with a +RE in 26%, 58%, and 84%, respectively (p = 0.001). Further, the extent of positivity was significantly correlated with the extent of residual tumor such that focal/minimal positivity was more commonly associated with micro/small +RE, whereas moderate/extensive positivity was associated with medium/large +RE. When the closest margin of the initial excision specimen was positive, > 0 < or = 1 mm, or 1.1-2 mm, a +RE was found in 56%, 41%, and 17%, respectively (p = 0.01) but did not correlate with the amount of residual tumor. The extent of specimen processing as reflected in the S:V ratio did not correlate with the probability of defining a measured margin as positive nor the probability of a +RE. In a univariate model, the extent of tumor in the re-excision and the histologic type of tumor in the re-excision were significantly associated with margin status and initial histopathology, respectively. The probability of finding a +RE, based on a multivariate model, was associated with the closeness and extent of margin involvement and initial histopathology of an EIC.

CONCLUSION

The relative closeness of tumor to the specimen edge and the extent of margin positivity are predictive for residual tumor, though with an error consistent with its limitations as a sampling procedure. The histopathology of tumor in the initial excision is predictive of the type of residual tumor and the extent of margin positivity was correlated with the amount of residual tumor.

Absence of disease phenotype and intergenerational stability of the CAG repeat in transgenic mice expressing the human Huntington disease transcript

The mutation underlying Huntington disease (HD) is CAG expansion in the first exon of the HD gene. In order to investigate the role of CAG expansion in the pathogenesis of HD, we have produced transgenic mice containing the full length human HD cDNA with 44 CAG repeats. By 1 year, these mice have no behavioral abnormalities and morphometric analysis at 6 (one animal) and 9 (two animals) months age revealed no changes. Despite high levels of mRNA expression, there was no evidence of the HD gene product in any of these transgenic mice. In vitro transfection studies indicated that the inclusion of 120 bp of the 5' UTR in the cDNA construct and the presence of a frameshift mutation at nucleotide 2349 prevented expression of the HD cDNA. These findings suggest that the pathogenesis of HD is not mediated through DNA-protein interaction and that presence of the RNA transcript with an expanded CAG repeat is insufficient to cause the disease. Rather, translation of the CAG is crucial for the pathogenesis of HD. In contrast to that seen in humans, the CAG repeat in these mice was remarkably stable in 97 meioses. This suggests that genomic sequences may play a critical role in influencing repeat instability.

Open-field behavior is not related to treadmill performance in exercising rats

We examined the association between open-field behavior and treadmill performance in 39 adult male Sprague-Dawley rats. Three daily, five-minute trials were conducted in an open field of 49 19 cm squares. The objectivity of the open-field test was established by intraclass correlations (R) for observer agreement on total squares traversed (R = .99) and a subjective behavioral rating scale for anxiety (R = .92). As expected, total squares were inversely correlated (r = -.86) with the subjective anxiety ratings. An independent observer also rated animals on treadmill performance across six daily, five-minute trials of level running at 15 m/min. Performance ratings were objective (rs = .89) and reproducible (R = .91). A volitional endurance run at 30 m/min on level grade was also conducted on a subsequent day. Extreme groups of low anxious (N = 7) and high anxious (N = 7) animals were then identified from convergent responses on total square traversals and the subjective behavioral ratings that were reproducible (R = .72 to .78) of trials two and three of the open-field test. Repeated measures ANOVA showed no group differences (p greater than 0.10) on mean treadmill performance across trials. Endurance was also the same for each group (p greater than 0.05). Our findings indicate that the open-field test is objective and reliable, and it does not reveal a selection bias effect on treadmill performance or endurance. Thus, open-field behavior can be used as a dependent or subject-matching variable in studies of adult male Sprague-Dawley rats when motor-driven treadmill running is a behavioral intervention or outcome measure.

Suppressed anger and blood pressure: the effects of race, sex, social class, obesity, and age

We studied 572 men and women who participated in a blood pressure screening program at a government unemployment office. Before having their blood pressures taken, the subjects completed a brief questionnaire that included two items measuring conflict over anger expression. Information was also obtained on obesity, race, sex, social class, and age. Across all subjects, systolic blood pressure was found to be significantly related to suppressed anger (p less than 0.016). Normotensive were twice as likely as hypertensives to be free of suppressed anger. This relationship remained after controlling for the covariates of age, social class, and obesity. The relationship between suppressed anger and systolic blood pressure was significant for white men, exhibited a trend in black men, and was not significant for women. In contrast to the systolic findings, suppressed anger was unrelated to diastolic pressure in all the analyses.

A waterborne outbreak of hepatitis E virus transmission in southwestern Vietnam

A hepatitis outbreak affecting primarily adults occurred in southwestern Vietnam, along the Hau river bordering Cambodia, in June and July 1994. One month after the outbreak, sera and epidemiologic information were collected from 150 subjects: 50 patient cases, 50 matched, healthy community controls, and 50 geographic controls living 50 km upriver. The prevalence of immunoglobulin G (IgG) to hepatitis E virus (HEV) was significantly (P < 0.001) higher (76%) among cases than among the matched (38%) and geographic (38%) control populations. Immunoglobulin M to HEV was detected by enzyme-linked immunosorbent assay and Western blot in 16% of sera collected from patients one month after the outbreak. Hepatitis E virus RNA was detected with the polymerase chain reaction in 6% of sera from patients; RNA was not detected in either control group. These results indicate that HEV was the etiologic agent responsible for the outbreak. Children were under-represented among clinical cases. River water served as the principal source for drinking and bathing among most (96%) of the case and control study populations. Boiling of drinking water was negatively associated (P < 0.05) with IgG anti-HEV seropositivity. Unusually heavy rainfall likely contributed to conditions that favored the outbreak. This is the first recognized outbreak of epidemic HEV transmission in Indo-China.

MDC-9 (ADAM-9/Meltrin gamma) functions as an adhesion molecule by binding the alpha(v)beta(5) integrin

MDC-9 is a widely expressed member of the metalloproteinase/disintegrin/cysteine-rich protein family. The disintegrin domain of MDC-9 lacks an RGD motif but has recently been reported to bind the alpha(6)beta(1) integrin; however, it is unclear whether MDC-9 can bind other integrins. In the present study myeloma cells, but not lymphoblastoid cells, were shown to bind to immobilised, recombinantly expressed MDC-9 disintegrin domain (A9dis). Binding was divalent cation-dependent, being supported by Mn(2+) and Ca(2+). Adhesion of myeloma cells to A9dis was completely inhibited by an antibody to the alpha(v)beta(5) integrin but not by antibodies to other subunits. RGD-containing peptides had no effect on binding, suggesting that MDC-9 interacts with alpha(v)beta(5) in an RGD-independent manner. Flow cytometric analyses demonstrated that myeloma cells, but not lymphoblastoid cells, expressed alpha(v)beta(5) on the cell membrane. These data indicated that the disintegrin domain of MDC-9 can function as an adhesion molecule by interacting with an alpha(v)beta(5) integrin.

Epidemiology of nosocomial infection and resistant organisms in patients admitted for the first time to an acute rehabilitation unit

The objectives of this study were to define the epidemiology of nosocomial bacterial colonization and infection and to define predictors of nosocomial infection among a cohort (n=423) of admissions to an acute rehabilitation unit. Overall, methicillin-resistant Staphylococcus aureus (MRSA) and enterococci were the most commonly identified colonizing organisms. Escherichia coli and Pseudomonas aeruginosa were the most commonly identified colonizing gram-negative bacilli. During 70 (16.5%) of the 423 hospitalizations in the unit, 94 nosocomial infections occurred. The most common infections were those of the urinary tract (30% of 94 infections) or a surgical site (17%), Clostridium difficile diarrhea (15%), and bloodstream infection (12.8%). Antibiotic-resistant bacteria most commonly caused bloodstream infection (41.7%) and surgical site infection (56.3%). Independent predictors of nosocomial infection at the time of admission were functional status (measured with the functional independence measure), APACHE III score, and spinal cord injury. In conclusion, gram-positive organisms were the predominant strains causing nosocomial colonization and infection. The logistic model, if verified, may be useful in defining patients who should be targeted for measures to prevent nosocomial infection.

The effect of several diphosphonates on acid phosphohydrolases and other lysosomal enzymes

Diphosphonates are known to inhibit bone resorption in tissue culture and in experimental animals. This effect may be due to their ability to inhibit the dissolution of hydroxyapatite crystals, but other mechanisms may be important. Since lysosomal enzymes have implicated in the process of bone resorption, we have examined the effect of several phosphonates and of a polyphosphate (P20,2) on lysosomal hydrolases derived from rat liver and rat bone. Dichloromethylene diphosphonate strongly inhibited acid beta-glycerophosphatase (EC 3.1.3.2) and acid p-nitrophenyl phosphatase (EC 3.1.3.2) and to a lesser degree (in descending order) acid pyrophosphatase (EC 3.1.3.-), arylsulfatase A (EC 3.1.6.1), deoxyribonuclease II(EC 3.1.4.6) and phosphoprotein phosphatase (EC 3.1.3.16) of rat liver. Inhibition of acid p-nitrophenyl phosphatase and arylsulfatase A was competitive. Ethane-1-hydroxy-1, 1-diphosphonate did not inhibit any of these enzymes, except at high concentrations. Neither dichloromethylene diphosphonate nor ethane-1-hydroxy-1, 1-diphosphonate had any effect on beta-glucuronidase (EC 3.2.1.31), arylesterase (EC 3.1.1.2) and cathepsin D (EC 3.4.23.5). Of several other phosphonates tested only undec-10-ene-1-hydroxy-1, 1-diphosphonic acid inhibited acid p-nitrophenyl phosphatase strongly, the polyphosphate (P20, I) had little effect. Acid p-nitrophenyl phosphatase in rat calvaria extract behaved in the same way as the liver enzyme and was also strongly inhibited by dichloromethylene diphosphonate, but not by ethane-1-hydroxy-1, 1-diphosphonate. It is suggested that the inhibition of bone resorption by dichloromethylene diphosphonate might be due in part to a direct effect of this diphosphonate on lysosomal hydrolases.

Critical closure in the canine pulmonary vasculature

The vascular pressure-flow (P-Q) relationships in zone II (West et al.) were studied in isolated canine left lower lobes, in order to characterize the total resistance in the pulmonary vascular bed with respect to incremental or flow resistance and critical closure. At each of five levels of static lung inflation, the P-Q relationship was curvilinear at low flow and rectilinear at higher flows. The slope of the linear portion was not significantly different at alveolar pressures (PA) = 5, 7, or 9 cm H2O, but decreased significantly at PA = 11 and 15 cm H2O ((P less than 0.05), indicating an increase in flow resistance. The pulmonary artery pressure (Ppa) fell to the same value at zero flow regardless of inflation level [10.1 +/- 1.0 (SD) cm H2O at PA = 5 cm H2O to 10.9 +/- 2.7 (SD) at PA = 15 cm H2O]. The Ppa intercept (Ppai), extrapolated from the linear portion of the P-Q curve and representing the average closing pressure for the vascular bed, increased from 16.0 +/- 1.8 (SD) cm H2O at PA = 5.0 to 26.5 +/- 4.4 (SD) cm H2O at PA = 15 (P less than 0.05) in a direct one-to-one relationship with the increase in PA. Since this results in a constant transmural gradient at the alveolar vessel level, these vessels must be the major fraction which undergo critical closure. Operationally defined vascular compliance, determined from the slope of a simultaneously obtained pressure-volume (P-V) curve, decreased significantly from 1.51 +/- 0.62 (SD) ml/cm H2O at PA = 5.0 H2O to 0.87 +/- 0.27 ml/cm H2O at PA = 15 cm H2O (P less than 0.05).

Bioprocess development for the production of a recombinant MUC1 fusion protein expressed by CHO-K1 cells in protein-free medium

The mucin MUC1 is a candidate for use in specific immunotherapy against breast cancer, but this requires the large-scale production of a MUC1 antigen. In this study, a bioprocess for the expression of a recombinant MUC1 fusion protein with a cancer associated glycosylation in CHO-K1 cells has been developed. Cells permanently expressing parts of the extracellular portion of MUC1 fused to IgG Fc were directly transferred from adherent growth in serum-containing medium to suspension culture in the protein-free ProCHO4-CDM culture medium. Using the Cellferm-pro system, optimal culture parameter as pH and pO(2) were determined in parallel spinner flask batch cultures. A pH of 6.8-7.0 and a pO(2) of 40% of air saturation was found to give best cell growth and productivity of secreted recombinant protein. Specific productivity strongly depended the pO(2) and correlated with the online monitored oxygen uptake rate (OUR) of the cells, which indicates a positive influence of the rate of oxidative phosphorylation on productivity. The optimised conditions were applied to continuous perfusion culture which gave very high cell densities and space time yields of the recombinant MUC1 fusion protein, allowing production at gram scale. The product degradation was much lower in supernatants from continuous perfusion culture compared to batch mode. Antibodies reacting with cancer associated MUC1 glycoforms strongly bound to the fusion protein, indicating that the desired glycoforms were obtained and suggesting that the recombinant MUC1 protein could be tested for use in immunotherapy.

The effects of ischemia, lactic acid and hypertonic sodium chloride on phrenic afferent discharge during spontaneous diaphragmatic contraction

In 9 sodium pentobarbital anaesthetized cats, 50 single-unit phrenic afferent recordings were determined during spontaneous ventilation, retrograde carotid arterial injection of lactic acid (LA, 0.1 N) and NaCl (5%), and a 2-min occlusion of the superior thoracic aorta. Fifty percent of the units had tonic low-frequency spontaneous discharge; 50% had phasic high-frequency discharge. Tonic fiber activity increased significantly with LA, NaCl and occlusion, while phasic fiber activity decreased in all 3 conditions. These results suggest that the diaphragm contains sensory endings sensitive to ischemia and extracellular metabolic changes.