Neoadjuvant chemotherapy, radical resection with intraoperative radiation therapy (IORT): improved treatment for gastric adenocarcinoma

BACKGROUND

Adenocarcinoma of the stomach and gastroesophageal junction results in substantial morbidity, locoregional recurrence, and death. Surgical procedures, even with adjuvant therapy, have not significantly improved survival. This study evaluated the toxicity, response rate, locoregional control, and survival of patients with locally advanced gastric cancer that was treated with neoadjuvant multimodality therapy.

METHODS

Patients with stage IIIA or early stage IV gastric adenocarcinoma received neoadjuvant 5-fluorouracil, Leucovorin, Adriamycin, and Cisplatin and underwent gastrectomy or esophagogastrectomy with intraoperative radiotherapy (IORT; 1000 cGY) to the gastric bed and postoperative radiation therapy.

RESULTS

Nine of 15 patients (60%) with transmural extension and/or nodal metastases received IORT. There were 2 pathologically complete responses at the primary site. Eleven of 15 patients (73%) had tumor in perigastric lymph nodes; however, 9 of 15 patients (60%) had mucin-filled nodes without tumor cells. Neoadjuvant treatment did not increase operative morbidity rates. Ten of 15 patients (67%) remain free of disease (median, 27 months; range, 6-60 months). Five patients died 13 to 41 months (median, 17 months) after diagnosis.

CONCLUSIONS

Neoadjuvant multimodality therapy with neoadjuvant 5-fluorouracil, Leucovorin, Adriamycin, and Cisplatin, radical resection with IORT, and postoperative radiation therapy is safe, can downstage tumors, provides improved locoregional control, and appears to cause significant tumor regression that may result in long-term survival or cure.

Prevention of primary cytomegalovirus disease in organ transplant recipients with oral ganciclovir or oral acyclovir prophylaxis

BACKGROUND

Optimal prophylaxis against cytomegalovirus (CMV) disease for organ transplant patients at risk for primary infection (donor seropositive, recipient seronegative, D+R-) remains to be determined. We hypothesized that prolonged oral ganciclovir therapy following intravenous therapy would provide increased protection.

METHODS

A total of 155 evaluable D+R- organ transplant recipients from 13 transplant centers were entered into the study: all received intravenous ganciclovir (5 mg/kg/day) for 5-10 days and then either oral acyclovir (400 mg tid) or oral ganciclovir (1 g tid) for an additional 12 weeks. Patients were assigned to their treatment groups at a central randomization site, with a separate randomization scheme for each of the organs transplanted (kidney, heart, or liver). In the case of kidney transplants, the patients were stratified according to source of the kidney (living related vs. cadaveric donor). The primary endpoint was the incidence of CMV disease in the first six months post-transplant.

RESULTS

Treatment with oral ganciclovir was associated with a significant decrease in the incidence of symptomatic disease or viremia when compared with the oral acyclovir group (32% vs. 50%, P<0.05). This difference was most marked in terms of tissue invasive disease: only 3 of 15 symptomatic patients in the ganciclovir group vs. 10 of 21 in the acyclovir group developed tissue-invasive infection (P<0.05). There was a significant difference in the time to CMV disease or viremia in the two groups: mean time 212+/-17 days post-transplant for the acyclovir group vs. 291+/-13 days for the ganciclovir group (P<0.001). The incidence of allograft rejection was 34% in the ganciclovir group and 46% in the acyclovir group (P=NS). Leukopenia was more common in the ganciclovir group (P<0.05), but in no case did it require drug discontinuation. Ganciclovir resistance did not develop in this study.

CONCLUSION

Prophylaxis with oral ganciclovir following a brief course of intravenous ganciclovir provides useful protection against primary CMV disease.

Multipoint linkage analysis of a candidate gene locus in rheumatoid arthritis demonstrates significant evidence of linkage and association with the corticotropin-releasing hormone genomic region

OBJECTIVE

Rheumatoid arthritis (RA) is the most common disabling autoimmune disease, affecting approximately 1% of the population. The disease etiology is unknown, but it involves inflammation and immune dysregulation and is influenced by genetic variation at both HLA and other, as-yet-unidentified genetic loci. Corticotropin-releasing hormone (CRH; or corticotropin-releasing factor), a primary regulator of the hypothalamic-pituitary-adrenal axis and a key element in the response to stress and inflammation, is a strong candidate gene for RA. We examined the role of DNA variation across the region containing this gene in multicase families with RA.

METHODS

We genotyped fluorescently labeled simple tandem repeat genetic markers from chromosome 8q13 in 295 families with multiple cases of RA. Singlepoint and multipoint nonparametric linkage analysis and association analysis using transmission disequilibrium testing (TDT) were also used.

RESULTS

Single-point linkage analysis using a microsatellite within 30 kb of the CRH locus (CRH.PCR at position 8q13) showed a significant excess of allele sharing in 295 United Kingdom RA families with at least 2 affected members (MapMaker/Sibs logarithm of odds [LOD] 1.4; P = 5.5x10(-3); mean identity by descent [ibd] sharing 55.9%). To provide a more detailed linkage map, a multipoint analysis was conducted with an additional 7 dinucleotide microsatellite markers (average heterozygosity 0.75) flanking the CRH locus. Significant linkage was detected over a 22-cM region between D8S285 and D8S530, with the maximum singlepoint LOD score of 1.77 at D8S1723 (MapMaker/Sibs P = 2.2x10(-3); mean ibd sharing 59.3%). Multipoint analysis showed strongest evidence for linkage at the same marker (multipoint LOD 1.78, P = 2.1x10(-3), mean ibd sharing 55.8%). TDT analysis showed significant association at the CRH locus (P = 2.6x10(-3)). CRH has a sibling relative risk of 1.14, and contributes <10% to the sibling relative risk of RA.

CONCLUSION

With the exception of HLA, this is the strongest evidence yet of a genetic locus that is both linked to and associated with RA, and provides an avenue for further genetic characterization and potentially novel therapeutic intervention.

A myosin phosphatase targeting subunit isoform transition defines a smooth muscle developmental phenotypic switch

Smooth muscle myosin phosphatase dephosphorylates the regulatory myosin light chain and thus mediates smooth muscle relaxation. The activity of this myosin phosphatase is dependent upon its myosin-targeting subunit (MYPT1). Isoforms of MYPT1 have been identified, but how they are generated and their relationship to smooth muscle phenotypes is not clear. Cloning of the middle section of chicken and rat MYPT1 genes revealed that each gene gave rise to isoforms by cassette-type alternative splicing of exons. In chicken, a 123-nucleotide exon was included or excluded from the mature mRNA, whereas in rat two exons immediately downstream were alternative. MYPT1 isoforms lacking the alternative exon were only detected in mature chicken smooth muscle tissues that display phasic contractile properties, but the isoform ratios were variable. The patterns of expression of rat MYPT1 mRNA isoforms were more complex, with three major and two minor isoforms present in all smooth muscle tissues at varying stoichiometries. Isoform switching was identified in the developing chicken gizzard, in which the exon-skipped isoform replaced the exon-included isoform around the time of hatching. This isoform switch occurred after transitions in myosin heavy chain and myosin light chain (MLC(17)) isoforms and correlated with a severalfold increase in the rate of relaxation. The developmental switch of MYPT1 isoforms is a good model for determining the mechanisms and significance of alternative splicing in smooth muscle.

Genetic polymorphism of IL-12 p40 gene in immune-mediated disease

Understanding of the genetic basis of autoimmune diseases is currently incomplete. Cytokine gene polymorphisms warrant consideration as factors explaining variation in the human immune and inflammatory responses and as candidate susceptibility genes for related pathological states. Interleukin 12 (IL-12) is a key regulator of the polarisation of immune responses to T helper 1 or 2 categories and plays a role in autoimmune and infectious diseases. Using a bioinformatic strategy, we aligned cDNA and expressed sequence tag sequences to identify putative polymorphic regions of the IL-12 p40 gene. Position 1188 in the 3' untranslated region (UTR) was polymorphic with the frequency of the common allele around 80% in healthy UK Caucasoids. PCR genotyping of multiple Caucasoid groups and an African group showed significant population variation. In a case-control design, the polymorphism was not associated with rheumatoid arthritis, Felty's syndrome or large granular lymphocyte syndrome with arthritis or multiple sclerosis. A nonsignificant increase in the B allele frequency was observed in the rare large granular lymphocyte syndrome without arthritis (odds ratio 2.02 95% CI 0.95-4.3). This new genetic marker could be useful in anthropological studies and should be investigated in other autoimmune, allergic, inflammatory and infectious diseases.

Forced expression of essential myosin light chain isoforms demonstrates their role in smooth muscle force production

The molecular determinants of the contractile properties of smooth muscle are poorly understood, and have been suggested to be controlled by splice variant expression of the myosin heavy chain near the 25/50-kDa junction (Kelley, C. A., Takahashi, M., Yu, J. H., and Adelstein, R. S. (1993) J. Biol. Chem. 268, 12848-12854) as well as by differences in the expression of an acidic (MLC(17a)) and a basic (MLC(17b)) isoform of the 17-kDa essential myosin light chain (Nabeshima, Y., Nonomura, Y., and Fujii-Kuriyama, Y. (1987) J. Biol. Chem. 262, 106508-10612). To investigate the molecular mechanism that regulates the mechanical properties of smooth muscle, we determined the effect of forced expression of MLC(17a) and MLC(17b) on the rate of force activation during agonist-stimulated contractions of single cultured chicken embryonic aortic and gizzard smooth muscle cells. Forced expression of MLC(17a) in aortic smooth muscle cells increased (p < 0.05) the rate of force activation, forced expression of MLC(17b) in gizzard smooth muscle cells decreased (p < 0.05) the rate of force activation, while forced expression of the endogenous MLC(17) isoform had no effect on the rate of force activation. These results demonstrate that MLC(17) is a molecular determinant of the contractile properties of smooth muscle. MLC(17) could affect the contractile properties of smooth muscle by either changing the stiffness of the myosin lever arm or modulating the rate of a load-dependent step and/or transition in the actomyosin ATPase cycle.

Growth in the presence of salicylate increases fluoroquinolone resistance in Staphylococcus aureus

Salicylate and acetylsalicylate slightly increased fluoroquinolone resistance in ciprofloxacin-susceptible and -resistant Staphylococcus aureus. Salicylate allowed a greater number of cells from ciprofloxacin-susceptible and -resistant strains to survive on high fluoroquinolone concentrations. Salicylate also increased the frequency with which a susceptible strain mutated to become more resistant to ciprofloxacin.

Developmental remodeling and shortening of the cardiac outflow tract involves myocyte programmed cell death

The embryonic outflow tract is a simple tubular structure that connects the single primitive ventricle with the aortic sac and aortic arch arteries. This structure undergoes a complex sequence of morphogenetic processes to become the portion of the heart that aligns the right and left ventricles with the pulmonary artery and aorta. Abnormalities of the outflow tract are involved in many clinically significant congenital cardiac defects; however, the cellular and molecular processes governing the development of this important structure are incompletely understood. Histologic and tissue-tagging studies indicate that the outflow tract tissues compact and are incorporated predominantly into a region of the right ventricle. The hypothesis tested in the current study was that cell death or apoptosis in the muscular portion of the outflow tract is an important cellular mechanism for outflow tract shortening. The tubular outflow tract myocardium was specifically marked by infecting myocytes of the chicken embryo heart with a recombinant replication-defective adenovirus expressing beta-galactosidase (beta-gal) under the control of the cytomegalovirus promoter. Histochemical detection of the beta -gal-labeled outflow tract myocytes revealed that the tubular structure shortened to become a compact ring at the level of the pulmonic infundibulum over several days of development (stages 25–32, embryonic days 4–8). The appearance of apoptotic cardiomyocytes was correlated with OFT shortening by two histologic assays, TUNEL labeling of DNA fragments and AnnexinV binding. The rise and fall in the number of apoptotic myocytes detected by histologic analyses paralleled the change in activity levels of Caspase-3, a protease in the apoptotic cascade, measured in outflow tract homogenates. These results suggest that the elimination of myocytes by programmed cell death is one mechanism by which the outflow tract myocardium remodels to form the proper connection between the ventricular chambers and the appropriate arterial trunks.

Forced expression of the homeodomain protein Gax inhibits cardiomyocyte proliferation and perturbs heart morphogenesis

The development of the tubular heart into a complex four-chambered organ requires precise temporal and region-specific regulation of cell proliferation, migration, death and differentiation. While the regulatory mechanisms in heart morphogenesis are not well understood, increasing attention has focused on the homeodomain proteins, which are generally linked to morphogenetic processes. The homeodomain containing gene Gax has been shown to be expressed in heart and smooth muscle tissues. In this study, the Gax protein was detected in the nuclei of myocardial cells relatively late in chicken heart development, at a time when myocyte proliferation is declining. To test the hypothesis that the Gax protein functions as a negative regulator of cardiomyocyte proliferation, a replication-defective adenovirus was used to force its precocious nuclear expression during chicken heart morphogenesis. In experiments in which Gax- and beta-galactosidase-expressing adenoviruses were co-injected, clonal expansion of myocytes was reduced, consistent with inhibition of myocyte proliferation. This effect on proliferation was corroborated by the finding that the percentage of exogenous Gax-expressing myocytes that were positive for the cell cycle marker PCNA decreased over time and was lower than in control myocytes. The precocious nuclear expression of Gax in tubular hearts resulted in abnormal heart morphology, including small ventricles with rounded apices, a thinned compact zone and coarse trabeculae. These results suggest a role for the Gax protein in heart morphogenesis causing proliferating cardiomyocytes to withdraw from the cell cycle, thus influencing the size and shape that the heart ultimately attains.

Palliation of AIDS-related primary lymphoma of the brain: observations from a multi-institutional database

PURPOSE

To catalogue the presenting symptoms of patients with AIDS who are presumed to have primary central nervous system lymphoma (PCNSL). To document the palliative efficacy of cranial irradiation (RT) relative to the endpoints of complete and overall response for the respective symptoms.

METHODS

An analysis of 163 patients with AIDS-related PCNSL who were evaluated at nine urban hospitals was performed. These patients were treated for PCNSL after the establishment of a tissue diagnosis or on a presumptive basis after failing empiric treatment for toxoplasmosis. All patients were treated between 1983 and 1995 with radiotherapy (median dose-fractionation scheme = 3 Gy x 10) and steroids (>90% dexamethasone). Because multiple fractionation schemes were used, prescriptions were converted to biologically effective doses according to the formula, Gy10 = Total Dose x (1 + fractional dose/alpha-beta); using an alpha-beta value of 10.

RESULTS

The overall palliative response rate for the entire group was 53%. In univariate analysis, trends were present associating complete response rates with higher performance status (KPS > or = 70 vs. KPS < or = 60 = 17% vs. 5%), female gender (women vs. men = 29% vs. 8%), and the delivery of higher biologically effective doses (BED) of RT (Gy10 > 39 vs. < or = 39 = 20% vs. 5%). In multivariate analysis of factors predicting complete response, both higher KPS and higher BED retained independent significance. A separate univariate analysis identified high performance status (KPS > or = 70 vs. KPS < or = 60 = 71% vs. 47%), and young age (< or = 35 vs. > 35 = 61% vs. 40%) as factors significantly correlating with the endpoint of the overall response. In multivariate analysis, high performance status and the delivery of higher biologically effective doses of irradiation correlated significantly with higher overall response rates.

CONCLUSION

Most AIDS patients who develop symptoms from primary lymphoma of the brain can achieve some palliation from a management program that includes cranial irradiation. Young patients with excellent performance status are most likely to respond to treatment. The delivery of higher biologically effective doses of irradiation also may increase the probability of achieving a palliative response.

Endothelin-1 alters the contractile phenotype of cultured embryonic smooth muscle cells

Smooth muscle tissues may be classified into phasic (fast) or tonic (slow) contractile phenotypes. This study was initiated to examine the specification of these phenotypes during development and the role of growth factors in this process. We used myosin light chain 17 (MLC17) and myosin heavy chain transcript splice variants as markers of the tonic (aortic) and phasic (intestinal) smooth muscle phenotypes in chick embryos. By reverse transcription-polymerase chain reaction, we determined embryonic days 6 to 16 to be a critical period for the establishment of these phenotypes. During this period, endothelin-1 is present at 40-fold-higher levels in aortic compared with intestinal tissues. To test the hypothesis that endothelin-1 may be involved in establishing the aortic (tonic) phenotype, we developed a system in which embryonic smooth muscle cells exhibit phasic and tonic contractile properties in vitro. Single-cell force measurements showed that cultured embryonic gizzard (phasic) cells developed force more rapidly (8 +/- 2 seconds) and achieved greater force (3.0 +/- 0.7 microN) than did cultured embryonic aortic (tonic) cells (20 +/- 0.7 seconds, 0.76 +/- 0.01 microN; P < .05) in response to depolarization. Chronic exposure of the phasic (gizzard) cells to endothelin-1 prolonged the time to peak force (24 +/- 3 seconds) and reduced the peak force (1.0 +/- 0.1 microN), so that the contraction resembled the tonic type. This effect, mediated by the endothelin-A receptor, was associated with a shift in MLC17 splicing to the tonic pattern. These results demonstrate that endothelin-1 is highly enriched in developing aortic compared with intestinal tissues and can convert phasic smooth muscle cells to the tonic type in vitro, suggesting a role for this growth factor during development in determining the contractile phenotype of smooth muscle cells.

Multiple overlapping processes underlying short-term synaptic enhancement

Recently there have been exciting advances in understanding the mechanisms and functional roles of a form of short-term synaptic enhancement (STE) that results from an activity-dependent accumulation of Ca2+ in the presynaptic terminal. This form of STE is composed of at least four processes: fast-decaying facilitation (FI), slow-decaying facilitation (F2), augmentation (AUG) and post-tetanic potentiation (PTP). Recent results suggest that these processes can now be distinguished mechanistically by the site of their induction within the presynaptic terminal: FI and F2 appear to be induced by a rapid, high concentration of Ca2+ at or near the site of exocytosis, whereas AUG and PTP seem to be induced by lower levels of Ca2+ with slower kinetics, possibly within the core of the terminal. STE is highly conserved across diverse species, and appears to serve as a flexible mechanism for temporal information processing in systems ranging from peripheral motor control to higher cortical integration.

Performance status and age as independent predictors of survival among AIDS patients with primary CNS lymphoma: a multivariate analysis of a multi-institutional experience

PURPOSE

There is limited information about the outcome of AIDS patients with primary central nervous system lymphoma treated with definitive irradiation. The purpose of this study was to determine factors associated with increased survival in such patients.

METHODS

An analysis was performed of 163 patients with AIDS who were evaluated at nine urban hospitals. These patients were treated for primary central nervous system lymphoma after the establishment of a tissue diagnosis or on a presumptive basis after failing empiric treatment for toxoplasmosis. All patients were treated between 1983 and 1995 with radiotherapy (median dose-fractionation scheme = 3 Gy x 10) and steroids (> 90% dexamethasone). Because multiple fractionation schemes were used, prescriptions were converted to biologically effective dose according to the formula Gy10 = Total Dose x (1 + fractional dose/alpha-beta), using an alpha-beta of 10.

RESULTS

Longer median survival times were associated with high Karnofsky performance status (KPS > or = 70 vs < or = 60: 181 vs 77 days), young age (< 35 vs > 35: 162 vs 61 days), and high total definitive irradiation doses (> 39 Gy10 vs < 39 Gy10: 162 vs 40 days). Tissue diagnosis, gender, race, number of lesions (solitary vs multiple), and the presence of other cancers did not influence outcome. In multivariate analysis, young age, high Karnofsky performance status, and the delivery of higher biologically effective doses of irradiation retained independent significance relative to the endpoint of survival.

CONCLUSIONS

Even at urban tertiary medical centers, few AIDS patients with intracranial lesions undergo biopsies to establish a precise tissue diagnosis. Survival following definitive irradiation is strongly related to two pretreatment factors (young age, high performance status) and one treatment factor (total biologically effective dose of cranial radiotherapy). These variables should be considered in selecting patients for definitive irradiation and in designing future studies.

Immediate-early gene responses to different cardiac loads in the ejecting rabbit left ventricle

Clinical and experimental observations in humans and animals have shown that different cardiac adaptations occur in response to different types of hemodynamic overload. However, very little is known about how different hemodynamic loads lead to these different cardiac adaptations. Accordingly, we studied the acute response of ejecting isolated rabbit hearts to independently varied systolic and diastolic mechanical loads at constant coronary perfusion pressure. We studied the combined effects of low end-diastolic volume (EDV) and low systolic ejection pressure (Pej), compared to low EDV and high Pej, high EDU and low Pej, and high EDV and high Pej, on the expression of c-fos, c-jun, and egr-1. Further, although we did not seek to clarify the role of these immediate-early genes in cardiac hypertrophy, we hypothesized that they should not all respond in the same manner to these different mechanical loads. In these ejecting hearts we found that the expression of these immediate-early genes did not all respond alike to the different mechanical loads: both c-fos and egr-1 were strongly induced at both 30 and 60 min. However, at 30 min only c-fos depended on the level of EDV (P = 0.01). Neither c-fos nor egr-1 was influenced by EDV at 60 min. The expression of c-jun was largely insensitive to all loading conditions. We conclude that EDV, independent of Pej, influences the pattern and time course of expression of some immediately-early genes and that these different immediate-early genes do not respond in parallel to changes in cardiac loading.

Expression of exogenous protein and analysis of morphogenesis in the developing chicken heart using an adenoviral vector

OBJECTIVES

Recombinant retroviral vectors have been shown to be useful tools for marking cells so as to follow their fates during development. The aim of this study was to determine the utility and advantages of an adenoviral vector as a tool to study the heart as it develops from a simple tube into a complex four-chambered organ.

METHODS

Replication-defective adenovirus (10(7) pfu) expressing beta-galactosidase (beta-gal) under the control of the RSV-LTR was applied to the external surface of embryonic stage 13-21 chick hearts in ovo. Embryos were incubated for up to an additional 96 h. Hearts were harvested at 12-24 h intervals and (1) whole-mount-stained for beta-gal and sectioned, (2) examined by electron microscopy and (3) homogenized and beta-gal activity measured with a luminescent assay.

RESULTS

beta-gal expression peaked at 48 h, when a significant percentage of the myocytes in the atrial and ventricular walls expressed the protein, and it comprised 0.5% of total heart protein. Significant levels were still expressed at 96 h. When applied to early-stage (13-16) embryos, expression occurred predominantly in cardiomyocytes. beta-gal marking of cells enabled us to identify the following morphogenic patterns: (1) cells of the conus region compact into the bulbis cordis; (2) by applying the virus at later stages, e.g. 21-22, it was evident that the epicardium invests the heart, after stage 17, in a dorsal to ventral and caudal to rostral direction; (3) at lower titers (10(5) pfu), the virus serves as a clonal marker through several cell divisions, with an estimated cell doubling time of 24 h.

CONCLUSIONS

Application of an adenoviral vector to early-stage embryonic chick heart results in substantial expression of exogenous protein in a significant percentage of cardiomyocytes without grossly affecting heart development. Adenoviral vectors are useful for following the fate of cells as the heart develops from a simple tube into a complex four-chambered organ and hold promise for enabling the expression of exogenous proteins which might alter cell behavior.

Characterization of cardiac gene cis-regulatory elements in the early stages of chicken heart morphogenesis

To study transcriptional regulation during early stages of cardiogenesis, stage 10-17 chicken embryo hearts were transfected efficiently within the intact embryo by application of plasmid DNA complexed to liposomes. Viral regulatory sequences and the skeletal alpha-actin, SERCA2 and ANF promoters activated expression of reporter genes in the primitive heart tube. Deletion and mutation analysis of the skeletal alpha-actin promoter revealed the importance of CArG cis-regulatory elements in enhancing transcription of the gene during early heart development. These results demonstrate the utility of this method for the identification of gene regulatory elements that specify the cardiac phenotype during early stages of heart morphogenesis.

Developmental and tissue distribution of expression of nonmuscle and smooth muscle isoforms of myosin light chain kinase

Using a combination of Northern and Western blotting and RT-PCR, we demonstrate the existence of a high molecular mass MLCK, which is expressed during chicken embryogenesis. It is expressed in developing smooth muscle containing tissues, and is detected at low concentrations in adult tissues. Direct sequencing of the RT-PCR product from embryonic tissue RNA revealed that the embryonic, high molecular mass MLCK is indeed the previously cloned "nonmuscle MLCK". Therefore, the high molecular mass MLCK should be termed embryonic/non-muscle MLCK isoform. Curiously, cultured embryonic gizzard and vascular smooth muscle cells express the lower molecular mass smMLCK protein, albeit at lower levels than in the in vivo tissues.

Norepinephrine and ANG II stimulate secretion of TGF-beta by neonatal rat cardiac fibroblasts in vitro

Transforming growth factor-beta (TGF-beta) is a ubiquitous growth-regulating protein that is capable of influencing the growth and function of heart cells in vitro. To better understand the role TGF-beta might play as a paracrine mediator of cardiac hypertrophy, the expression, secretion, and growth effects of TGF-beta were examined. Neonatal cardiac fibroblasts in vitro secreted latent TGF-beta 1 and TGF-beta 2 as high as 15 ng/10(6) cells. Angiotensin II (ANG II) and norepinephrine (NE) each augmented up to threefold the expression and secretion of latent TGF-beta 1 and TGF-beta 2 and also induced a shift in isoform predominance from beta 1 to beta 2. Each agent individually produced hypertrophic growth of neonatal cardiocytes and hyperplastic growth of cardiac fibroblasts. Paradoxically, the combination of NE and ANG II at intermediate and high concentrations resulted in less TGF-beta secretion (compared with either agent alone) and in hypertrophic growth of fibroblasts. These results suggest that the growth-promoting effects of ANG II and NE may in part be mediated via a paracrine stimulation of TGF-beta secretion.

Accumulation and proteolytic processing of vicilin deletion-mutant proteins in the leaf and seed of transgenic tobacco

Vicilin, a 7S globulin of Pisum sativum L. seed, accumulates in protein-storage vacuoles (protein bodies) of cotyledonary storage-parenchyma cells. The synthesis and proteolytic processing of various genetically engineered proteins within the leaf and seed of a heterologous (tobacco, Nicotiana tabacum L.) host was examined. A modified vicilin gene, in which the DNA sequence corresponding to the signal peptide was removed, resulted in a polypeptide of 50 kDa in the tobacco leaf and seed; none of the normal proteolytic cleavage products characteristic of expression of an unmodified vicilin gene were obtained. Likewise, no vacuolar accumulation of this mutant vicilin occurred in leaf protoplasts, which is also supportive of the predicted cytosolic localization for this protein. In-frame deletions were made within the region of the vicilin gene encoding the mature protein, to eliminate the N-terminal 28 and 121 amino acids and the C-terminal 69 residues, while maintaining an intact signal peptide. All of these "mature" deletion-mutant proteins were accumulated to only low levels in the host, but exhibited the predicted molecular weight and underwent some normal proteolytic processing in the seed. Mutant vicilin proteins having deletions in either the N-terminus (delta NT 121) or C-terminus (delta CT 69) were not found in appreciable amounts within the vacuolar fraction of transgenic tobacco leaf protoplasts, perhaps due to protein degradation in this compartment. Compared with the intact vicilin, oligomer assembly of the C-terminal deletion-mutant protein was disrupted in leaf cells, which may have further affected protein stability.(ABSTRACT TRUNCATED AT 250 WORDS)

Collagen synthesis inhibitors disrupt embryonic cardiocyte myofibrillogenesis and alter the expression of cardiac specific genes in vitro

The extra-cellular matrix has been demonstrated to play an important role in the differentiation of a number of cell types in vitro. The purpose of this study was to establish the role of ECM collagen synthesis in regulating growth and differentiation of embryonic cardiocytes in vitro. We report that treatment of embryonic cardiocytes in vitro with two chemically distinct inhibitors of collagen synthesis, cis-hydroxy-L-proline and ethyl-3,4-dihydroxybenzoate, effectively inhibits collagen secretion. This results in disruption of myofibrillogenesis as seen by immunocytochemistry and electron microscopy, and absence of beating. The expression of muscle specific genes TroponinT and Myosin Heavy Chain are reduced, while the expression of the housekeeping gene glyceraldehyde phosphate dehydrogenase is uneffected. All of these effects are reversible. The structural effects are not prevented by growing the cells on various substrates, including denatured collagen, collagen type IV, laminin and Matrigel. Thus, inhibition of collagen secretion disrupts myofibrillogenesis and results in the alteration of expression of muscle-specific genes, suggesting that collagen synthesis plays an essential role in maintaining the differentiated phenotype of cardiocytes.

Confocal laser scanning microscopy reveals voltage-gated calcium signals within hippocampal dendritic spines

The induction of long-term potentiation (LTP) is generally assumed to be triggered by Ca2+ entry into dendritic spines via NMDA receptor-gated channels. A previous computational model proposed that spines serve several functions in this process. First, they compartmentalize and amplify increase in [Ca2+]i. Second, they augment the nonlinear relationship between synaptic strength and the probability or magnitude of LTP induction. Third, they isolate the metabolic machinery responsible for LTP induction from increases in [Ca2+]i produced by voltage-gated Ca2+ channels in the dendritic shaft. Here we examine this last prediction of the model using methods that combine confocal microscopy with simultaneous neurophysiological recordings in hippocampal brain slices. Either of two Ca(2+)-sensitive dyes were injected into CA1 pyramidal neurons. Direct depolarization of the neurons via the somatic electrode produced clear increases in Ca2+ signals within the dendritic spines, a result that was not predicted by the previous spine model. Our new spine model suggests that some of this signal could theoretically result from Ca(2+)-bound dye diffusing from the dendritic shaft into the spine. Dye diffusion alone cannot, however, explain the numerous cases in which the Ca2+ signal in the spine was considerably larger than that in the adjacent dendritic shaft. The latter observations raise the possibility of voltage-gated Ca2+ entry directly into the spine or else perhaps via Ca(2+)-dependent Ca2+ release. The new spine model accommodates these observations as well as several other recent experimental results.

Characterization of promoter elements of the rabbit cardiac sarcoplasmic reticulum Ca(2+)-ATPase gene required for expression in cardiac muscle cells

The sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2) plays a critical role in the contractile performance of cardiac and slow-twitch skeletal muscle by restoring cytosolic calcium to low resting levels during the contractile cycle. We have previously shown that SERCA2 expression in the heart is altered by a number of pathophysiological stimuli. In an effort to define molecular mechanisms regulating expression of the SERCA2 gene in cardiac muscle cells, deletions of a 1460-bp promoter fragment were generated and inserted into a luciferase reporter plasmid. Promoter constructs were transiently transfected into embryonic cardiocytes and skeletal muscle cell lines Sol 8 and C2C12 in vitro and injected into adult myocardium in vivo. Results demonstrate that sequences from the transcription start site to -284 are both necessary and sufficient for high-level transcription of the reporter gene in differentiating muscle cells and in fetal cardiocytes in culture. We further demonstrate that this promoter fragment is highly active in vivo when injected into rat hearts, suggesting that the same regulatory elements are functional in vivo as well as in vitro. The region of the gene from -284 to -658 exerts a modest positive effect in cardiocytes and Sol 8 myotubes but exerts a negative effect in C2C12 fast skeletal muscle cells. This initial analysis of transcriptional regulation of the SERCA2 gene will serve as a foundation for the study of alterations of expression of the gene in pathological conditions.

A district health service in Khayelitsha--panacea or pipedream?

Khayelitsha is an underserviced, largely informal urban settlement on the edge of Cape Town. It is home to some 350,000 people. This paper maintains that a district health service would be beneficial in Khayelitsha. Advantages include (i) the integration and co-ordination of services with coherent management of health care; (ii) the ability to prioritise and act on problems with the full range of preventive and curative measures as well as intersectoral support; and (iii) the accountability of health providers. Some of the steps taken towards the initiation of a district health service are illustrated in a discussion of the recent changes in health service structures in Khayelitsha. There are many obstacles to the implementation of a formal district health service and these are discussed briefly.

Measles vaccination coverage and its determinants in a rapidly growing peri-urban area

A study was undertaken to ascertain the vaccination coverage of children aged 12-23 months living in Khayelitsha, a peri-urban township outside Cape Town, and to identify factors associated with measles vaccination coverage. A stratified proportional cluster sampling technique was used to select 46 clusters of 10 children each. Three strata were defined according to area of residence. The vaccination status of each child was determined from the preschool card. Usable information was obtained for 432 children; in 75.4% of cases the respondent was the child's mother, and 69.4% of children possessed a preschool card. Measles vaccination coverage was 63.5% (95% confidence interval 58-67%). Three factors had a significant association with incomplete measles vaccination: less than 6 months' residence in the area (odds ratio (OR) 3.1), having been born outside Cape Town (OR 2.5), and home delivery (OR 2.0). The mothers' level of education and children's age were not associated with measles vaccination status. Children in the New Shanty area were identified as a high-risk group. Carers of children in the New Shanty area were the least likely to know of the need for measles vaccination and to be visited by a community health worker. Greater efforts are required to identify high-risk children and areas.

Innovative techniques in radiation oncology. Clinical research programs to improve local and regional control in cancer

There is a growing importance in failure analysis in cancer management. In these analyses locoregional failure as the cause of death emerges as a significant problem in many tumor sites, e.g., head and neck cancer, gynecologic cancer, genitourinary cancer. Because of these data, the radiation oncology community has attributed high priority to research efforts to improve locoregional control. These efforts include the following: (1) brachytherapy alone or with external beam radiation therapy or surgery; (2) intraoperative radiation therapy; (3) hyperthermia with radiation therapy; (4) particle irradiation (protons, neutrons, stripped nuclei, and pions); and (5) routes of administration of the treatment, including infusional (intravenous) chemotherapy with radiation therapy, intraarterial monoclonal antibodies with radionuclides, and intraarterial chemotherapy with radiation therapy. Each area of investigation is discussed.