Tear function and goblet cell density after pterygium excision

PURPOSE

To evaluate the short-term effect of pterygium excision on tear function and conjunctival goblet cell density.

METHODS

In all, 70 patients (70 eyes) with primary pterygia who underwent a bare-sclera procedure were enrolled in this study. Tear break-up time, Schirmer, and tear-ferning tests and conjunctival goblet cell density obtained by impression cytology were evaluated before and 1 month after surgery.

RESULTS

At 1 month postoperation, the tear break-up time (11.49+/-3.76 s) was significantly prolonged when compared with the preoperation tear break-up time (9.74+/-3.43 s, P=0.002). Before surgery, only 17% of the patients showed normal crystallization in the tear-ferning test. This proportion was significantly increased to 90% 1 month after surgery (P<0.001). There is no significant difference in the Schirmer test value between pre- and postsurgery (P>0.05). The mean goblet cell density in conjunctival impression specimens before surgery was 41.82+/-18.29/10 fields, which was increased significantly 1 month after surgery (P<0.001) with a mean cell density of 50.67+/-18.71/10 fields.

CONCLUSION

Tear function in patients with primary pterygium improves after pterygium excision, which indicates that pterygium has a close relationship with dry eye.

Resistin is not associated with insulin sensitivity or the metabolic syndrome in humans

AIMS/HYPOTHESIS

The aim of this study was to further elucidate the relationship between resistin and insulin sensitivity, body fat distribution and the metabolic syndrome in humans.

METHODS

We measured plasma resistin levels in 177 non-diabetic subjects (75 male, 102 female; age 32-75 years). BMI, waist circumference, blood pressure, lipids, glucose, plasminogen-activator inhibitor 1 (PAI-1), adiponectin and leptin levels were also measured. The insulin sensitivity index (S(I)) was quantified using Bergman's minimal model. Intra-abdominal fat (IAF) and subcutaneous fat (SQF) areas were quantified by CT scan. Presence of metabolic syndrome criteria was determined using the National Cholesterol Education Program Adult Treatment Panel III guidelines.

RESULTS

When subjects were divided into categories based on BMI (< or > or =27.5 kg/m(2)) and S(I) (< or > or = 7 x 10(-5) min(-1) [pmol/l](-1)), resistin levels did not differ between the lean, insulin-sensitive (n=53, 5.36+/-0.3 ng/ml), lean, insulin-resistant (n=67, 5.70+/-0.4 ng/ml) and obese, insulin-resistant groups (n=48, 5.94+/-0.4 ng/ml; ANOVA p=0.65). Resistin correlated with age (r=-0.22, p<0.01), BMI (r=0.16, p=0.03) and SQF (r=0.19, p=0.01) but not with S(I) (p=0.31) or IAF (p=0.52). Resistin did not correlate with the number of metabolic syndrome criteria or any of the individual metabolic syndrome criteria. In contrast, adiponectin, PAI-1 and leptin each correlated with IAF, SQF and S(I). Additionally, the number of metabolic syndrome criteria correlated with adiponectin (r=-0.32, p<0.001), leptin (r=0.31, p<0.001) and PAI-1 (r=0.26, p=0.001).

CONCLUSIONS/INTERPRETATION

In contrast to other adipokines, resistin is only weakly associated with body fat and is unlikely to be a major mediator of insulin resistance or the metabolic syndrome in humans.

An independent confirmation of a quantitative trait locus for milk yield and composition traits on bovine chromosome 26

Several reports have demonstrated that bovine chromosome 26 (BTA26) harbours significant or suggestive quantitative trait loci (QTL) for milk production and composition traits in dairy cattle. Our previous study showed that a C/T substitution in the bovine TCF7L2 gene on BTA26 was significantly linked to QTL for protein yield (PY) in a Canadian dairy cattle population. Actually, this polymorphism was one of the markers derived from a genome-wide screening of QTL for milk PY using an amplified fragment length polymorphism technique combined with a DNA pooling strategy. In the present study, 990 Holstein bulls with complete genotype and phenotype data from 14 sire families were analysed to confirm, if the QTL effects exist in other populations. Statistical analysis revealed that this marker was significantly associated with PY, protein percentage, milk yield and fat yield (FY) (p < 0.001) in the US Holstein population. These results indicate that this QTL region has a pleiotrophic effecton different milk traits and is portable in different populations.

Synthesis, in vitro anticancer evaluation, and interference with cell cycle progression of N-phosphoamino acid esters of zidovudine and stavudine

A series of N-diisopropylphosphoryl (DIPP) L-amino acid ester prodrugs of zidovudine (AZT) (3a-3e) and stavudine (d4T) (4a-4e) has been prepared. The activity of these compounds against MCF-7 cells (human pleural effusion breast adenocarcinoma cell line) and K562 cells (human chronic myeloid leukemia (CML) cell line) was evaluated. In difference from that of AZT amino acid phosphoramidates, the alophatic amino acid esters of AZT were found to be more cytotoxic than the aromatic analogues toward MCF-7 cell. Two DIPP-L-amino acid esters of d4T 4b (CC50 = 83 microM) and 4c (CC50 = 182 microM) were found to be more cytotoxic than the parent drug toward K562 cells. MCF-7 and K562 cell cycle disturbance was investigated showing detectable blockade in the S phase when exposed to biologically active AZT, 3a, 3b, 3c, 4b and 4c, indicating that they inhibit cell growth by blocking cell cycle progression. Together with previous reports, present findings suggest that anti-breast cancer activity of AZT may be due to hamper DNA synthesis.

Systemic AL amyloidosis due to non-Hodgkin's lymphoma: an unusual clinicopathologic association

Systemic AL amyloidosis (AL) is a disorder in which light chains form fibrillar deposits, leading to organ dysfunction and death. Rarely, AL has been associated with non-Hodgkin's lymphoma (NHL), although this association has not been well characterized. We report a series of six patients with AL associated with NHL, primarily lymphoplasmacytic lymphoma. Organ involvement was variable, with frequent bulky lymphadenopathy and visceral cavity deposits, but no cardiac involvement. Positron emission tomography scans were negative. Bone marrow and lymph node biopsies showed a mixed population of CD20+ lymphoid and CD138+ plasma cells. Serum free light chains were elevated, and correlated with response to therapy. Immunoglobulin light chain variable region (Ig VL) germline gene use was typical for AL, reflecting previously observed correlations between germline gene use and organ tropism. Five patients received rituximab-based therapies with two responses. Two patients underwent autologous stem cell transplantation with one complete haematological response. Four patients survive at 10-132 months from diagnosis. AL with NHL has distinctive clinical features but employs the same Ig VL gene repertoire as AL with clonal plasma cell dyscrasias. Serial serum free light chain levels are useful for tracking response to therapy. Treatments aimed at both lymphoid and plasma cell components appear warranted.

Cellular specificity of proexendin-4 processing in mammalian cells in vitro and in vivo

Glucagon-like peptide-1 (GLP-1) is a potent stimulator of glucose-dependent insulin secretion. Exendin-4(1-39) (Ex-4), isolated from Gila monster venom, is a highly specific GLP-1 receptor agonist that exhibits a prolonged duration of action in vivo. Although the processing mechanisms underlying liberation of GLP-1 from its prohormone have been elucidated, those for Ex-4 remain unknown. To examine the requirements for proEx-4 processing in mammalian cells, BHK fibroblasts, InR1-G9 islet A cells, and AtT-20 corticotropes, which express different prohormone convertases (furin, prohormone convertase 2, and prohormone convertase 1, respectively) were transfected with full-length lizard proEx-4, and the processing of proexendin was examined by HPLC and RIA (n = 3). All of the transfected cell lines exhibited Ex-4-like immunoreactivity in the media, and Ex-4-like immunoreactivity was detected in extracts of InR1-G9 and AtT-20 cells. However, only media and extracts from AtT-20 cells (not InR1-G9 and BHK cells) contained a single peak by HPLC corresponding to synthetic Ex-4. To establish whether proEx-4 can be processed to Ex-4 in nonimmortalized mammalian cells in vivo, the molecular forms of exendin-4 were examined in mice expressing a metallothionein-proEx-4 transgene (n = 3-6 for both males and females). ProEx4 mRNA transcripts were detected by RT-PCR in a broad range of both endocrine and nonendocrine tissues. Ex-4-like immunoreactivity was detected in pituitary, fat, adrenals, and testes; however HPLC analyses demonstrated that processed Ex-4 was found only in adrenals and testes. These results indicate that lizard proEx-4 is processed to mature bioactive Ex-4 in both rodent endocrine and nonendocrine mammalian cell types in vitro and in murine tissues in vivo. These findings may be useful for engineering cells that express a lizard pro-Ex4 transgene for the treatment of type 2 diabetes.

[Clinical comparison between intraoperative local arterial infusion chemotherapy and systemic venous chemotherapy of gastric cancer]

OBJECTIVE

To evaluate the effect of intraoperative local arterial infusion chemotherapy for gastric cancer.

METHODS

The effects of intraoperative local arterial infusion chemotherapy in 40 patients with gastric cancer were assessed. Twenty-four patients with gastric cancers who underwent the intraoperative systemic chemotherapy were taken as controls. The removed specimens were examined microscopically to show the degeneration and necrosis of the tumour cell.

RESULTS

After the treatment of the tumour cells, all of the cases in the study group showed various degrees of degeneration and necrosis. The immediate effective rate was 95% for the the study group but only 41.67% for the control group (P < 0.05).

CONCLUSION

Intraoperative local arterial infusion chemotherapy for gastric cancer has good immediate effect and little side effect; it prevents the intraoperative iatrogenic metastases and implantation and decreases the postoperative recurrence of gastric cancer.

B-Myc, a proximal caput epididymal protein, is dependent on androgens and testicular factors for expression

The myc family of transcriptional regulators carries out critical roles in the control of cellular proliferation, differentiation, apoptosis, and tumorigenesis. The B-myc gene is a recently identified myc family member that has not been well characterized. Previously, we have shown that B-Myc inhibits the ability of c-Myc to transform cells and can inhibit cellular proliferation. Because B-myc is primarily expressed in hormonally regulated tissues with predominant expression in the epididymis, we examined in greater detail B-myc expression in the epididymis to ultimately understand potential roles B-myc may play in this and other hormonally regulated tissues. Herein we demonstrate that, in contrast to c-myc, B-myc mRNA and protein expression are highly regionalized with expression predominantly in the proximal caput epididymal region. Furthermore, in situ and immunohistochemical analyses show that within the epididymis B-myc mRNA and protein are specifically expressed by the epithelial cells and that B-Myc protein is localized to both the nuclear and cytosolic compartments. Castration and hormone replacement studies further show that expression of the B-myc mRNA is highly dependent on the presence of androgens and testicular factors. Finally, mRNA turnover studies demonstrate that the B-myc mRNA is relatively unstable with a half-life of 3.5 h. Taken together, the highly restricted and regulated expression of the B-myc gene suggests it may play important regulatory roles in the epididymis and perhaps other hormonally regulated tissues.

[Eight cases of rhabdomyosarcoma in head and neck]

OBJECTIVE

To improve the clinical diagnosis and treatment level of rhabdomyosarcoma in head and neck.

METHOD

It was based on the documents that 8 cases of rhabdomyosarcoma in head and neck had been diagnosed by pathological diagnosis.

RESULT

The 8 cases were treated by operation. Among 8 patients, 5 took radiotherapy after operation. 1 took chemotherapy after operation. We kept in touch with 7 patients, the survival rate of 5 years was 57.1% (4/7).

CONCLUSION

We must pay attention to the painful or painless phyma in the otolaryngology and head and neck. It has the possibility of being rhabdomyosarcoma. We diagnose the rhabdomyosarcoma through biopsy and immuohistochemistry and with the references from the examination of CT, MR. In order to improve the survival rate of patients of rhabdomyosarcoma, we should use the comprehensive treatment, including operation, radiotherapy, and chemotherapy.

Biological activities of glucagon-like peptide-1 analogues in vitro and in vivo

Studies support a role for glucagon-like peptide 1 (GLP-1) as a potential treatment for diabetes. However, since GLP-1 is rapidly degraded in the circulation by cleavage at Ala(2), its clinical application is limited. Hence, understanding the structure-activity of GLP-1 may lead to the development of more stable and potent analogues. In this study, we investigated GLP-1 analogues including those with N-, C-, and midchain modifications and a series of secretin-class chimeric peptides. Peptides were analyzed in CHO cells expressing the hGLP-1 receptor (R7 cells), and in vivo oral glucose tolerance tests (OGTTs) were performed after injection of the peptides in normal and diabetic (db/db) mice. [D-Ala(2)]GLP-1 and [Gly(2)]GLP-1 showed normal or relatively lower receptor binding and cAMP activation but exerted markedly enhanced abilities to reduce the glycemic response to an OGTT in vivo. Improved biological effectiveness of [D-Ala(2)]GLP-1 was also observed in diabetic db/db mice. Similarly, improved biological activity of acetyl- and hexenoic-His(1)-GLP-1, glucagon((1-5)-, glucagon((1-10))-, PACAP(1-5)-, VIP(1-5)-, and secretin((1-10))-GLP-1 was observed, despite normal or lower receptor binding and activation in vitro. [Ala(8/11/12/16)] substitutions also increased biological activity in vivo over wtGLP-1, while C-terminal truncation of 4-12 amino acids abolished receptor binding and biological activity. All other modified peptides examined showed normal or decreased activity in vitro and in vivo. These results indicate that specific N- and midchain modifications to GLP-1 can increase its potency in vivo. Specifically, linkage of acyl-chains to the alpha-amino group of His(1) and replacement of Ala(2) result in significantly increased biological effects of GLP-1 in vivo, likely due to decreased degradation rather than enhanced receptor interactions. Replacement of certain residues in the midchain of GLP-1 also augment biological activity.

Fine mapping of Hyplip1 and the human homolog, a potential locus for FCHL

Familial combined hyperlipidemia (FCHL) is a common genetic dyslipidemia predisposing to premature coronary heart disease (CHD). We previously identified a locus for FCHL on human Chromosome (Chr) 1q21-q23 in 31 Finnish FCHL families. We also mapped a gene for combined hyperlipidemia (Hyplip1) to a potentially orthologous region of mouse Chr 3 in the HcB-19/Dem mouse model of FCHL. The human FCHL locus was, however, originally mapped about 5 Mb telomeric to the synteny border, the centromeric part of which is homologous to mouse Chr 3 and the telomeric part to mouse Chr 1. To further localize the human Hyplip1 homolog and estimate its distance from the peak linkage markers, we fine-mapped the Hyplip1 locus and defined the borders of the region of conserved synteny between human and mouse. This involved establishing a physical map of a bacterial artificial chromosome (BAC) contig across the Hyplip1 locus and hybridizing a set of BACs to both human and mouse chromosomes by fluorescence in situ hybridization (FISH). We narrowed the location of the mouse Hyplip1 gene to a 1.5-cM region that is homologous only with human 1q21 and within approximately 5-10 Mb of the peak marker for linkage to FCHL. FCHL is a complex disorder and this distance may, thus, reflect the well-known problems hampering the mapping of complex disorders. Further studies identifying and sequencing the Hyplip1 gene will show whether the same gene predisposes to hyperlipidemia in human and mouse.

Tecto-isthmo-optic transmission in pigeons is mediated by glutamate and nitric oxide

The isthmo-optic nucleus of the centrifugal system in birds receives primarily input from the ipsilateral tectum and projects to the contralateral retina. The present study using brain slices and microiontophoresis shows that synaptic transmission from the tectum to the centrifugal nucleus in pigeons is excitatory. About 75% of tecto-isthmo-optic fibers are glutamatergic, mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid but not N-methyl-D-aspartate-receptors, and 25% of others may use nitric oxide as a transmitter or modulator. On the other hand, about 60% of isthmo-optic cells receive glutamatergic afferents, 20% receive nitric oxidergic afferents, and 20% of others receive both glutamatergic and nitric oxidergic afferents from the tectum. In the last group, it is more likely that both glutamate and nitric oxide may co-release from the same tecto-isthmo-optic terminals. All the isthmo-optic cells examined in the present study also receive gamma-aminobutyric acid (GABA)ergic afferents via GABA(A) and GABA(B) receptors probably from some extratectal structures.

Visual responses of neurons in the pretectal nucleus lentiformis mesencephali to moving patterns within and beyond receptive fields in pigeons

Large-field patterns are effective stimuli for eliciting visual responses from neurons in the pretectal nucleus lentiformis mesencephali of nonmammals. The present study shows that stimulation beyond the receptive field does not contribute to the visual responses of neurons in the nucleus lentiformis mesencephali in two respects. First, changes in the direction and velocity of motion beyond the receptive field did not affect the visual responses of the pretectal cells to motion within the receptive field. Second, time differences in the onset of stimulation within and outside the receptive field did not influence the visual responses of the pretectal cells to motion in the receptive field, implying that there may be no long-range interaction between the receptive field and its surrounding field. The present study also indicates that the pretectal cells are not only sensitive to the direction and velocity of motion, but also to the size and density of dots in a random-dot pattern moving through the receptive field. Taken together with previous studies, these results suggest that the receptive field of the pretectal cells within the nucleus lentiformis mesencephali is large in size but well defined in boundaries, and that the pretectal cells respond to motion of visual stimuli within but not beyond their receptive fields.

Characterization of glucagon-like peptide-1 receptor-binding determinants

Glucagon-like peptide 1 (GLP-1) is a potent insulinotropic hormone currently under study as a therapeutic agent for type 2 diabetes. Since an understanding of the molecular mechanisms leading to high-affinity receptor (R) binding and activation may facilitate the development of more potent GLP-1R agonists, we have localized specific regions of GLP-1R required for binding. The purified N-terminal fragment (hereafter referred to as NT) of the GLP-1R produced in either insect (Sf9) or mammalian (COS-7) cells was shown to bind GLP-1. The physical interaction of NT with GLP-1 was first demonstrated by cross-linking ((125)I-GLP-1/NT complex band at approximately 28 kDa) and secondly by attachment to Ni(2+)-NTA beads. The GLP-1R NT protein attached to beads bound GLP-1, but with lower affinity (inhibitory concentration (IC(50)): 4.5 x 10(-7) M) than wild-type (WT) GLP-1R (IC(50): 5.2 x 10(-9)M). The low affinity of GLP-1R NT suggested that other receptor domains may contribute to GLP-1 binding. This was supported by studies using chimeric glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptors. GIP(1-151)/GLP-1R, but not GIP(1-222)/GLP-1R, exhibited specific GLP-1 binding and GLP-1-induced cAMP production, suggesting that the region encompassing transmembrane (TM) domain 1 through to TM3 was required for binding. Since it was hypothesized that certain charged or polar amino acids in this region might be involved in binding, these residues (TM2-TM3) were analyzed by substitution mutagenesis. Five mutants (K197A, D198A, K202A, D215A, R227A) displayed remarkably reduced binding affinity. These studies indicate that the NT domain of the GLP-1R is able to bind GLP-1, but charged residues concentrated at the distal TM2/extracellular loop-1 (EC1) interface (K197, D198, K202) and in EC1 (D215 and R227) probably contribute to the binding determinants of the GLP-1R.

B-Myc is preferentially expressed in hormonally-controlled tissues and inhibits cellular proliferation

The myc family of genes plays an important role in several cellular processes including proliferation, apoptosis, differentiation, and transformation. B-myc, a relatively new and largely unstudied member of the myc family, encodes a protein that is highly homologous to the N-terminal transcriptional regulatory domain of c-Myc. Here, we show that high level B-myc expression is restricted to specific mouse tissues, primarily hormonally-controlled tissues, with the highest level of expression in the epididymis. We also report the identification of the endogenous B-Myc protein from mouse tissues. Like other Myc family proteins, B-Myc is a short-lived nuclear protein which is phosphorylated on residues Ser-60 and Ser-68. Rapid proteolysis of B-Myc occurs via the ubiquitin-proteasome pathway. Finally, we found that overexpression of B-Myc significantly slows the growth of Rat la fibroblasts and COS cells suggesting B-Myc functions as an inhibitor of cellular proliferation.

[Assessment on application of Chinese herbs in process of corticosterone reduction in nephrotic syndrome]

OBJECTIVE

To evaluate the effect of Chinese herbs in the process of corticosterone (CS) reduction in nephrotic syndrome.

METHODS

One hundred and twenty patients of idiopathic nephrotic syndrome sensitive to prednisone treatment were divided into two groups randomly. The dosage of prednisone used was reduced by routine in both groups but Chinese herbal treatment was added to the treated group in the period of prednisone reduction. The effect of Chinese herbs was estimated by observing the recurrence rate of disease and side-effects of prednisone.

RESULTS

The recurrence rate of disease and the occurrence rate of side-effects of prednisone in the treated group were lesser than that in the control group significantly (P < 0.01).

CONCLUSION

Additional Chinese herbs in the process of CS reduction in the treatment of CS sensitive nephrotic syndrome could extenuate markedly the recurrence rate of disease and the side-effect of CS reduction.

[Cleft palate repair of infants with 32 cases]

OBJECTIVE

To search a proper time for cleft palate repair.

METHODS

Thirty-two patients with unilateral and bilateral cleft palate, aged from 25 days to 3 months, were undergoing the cleft palate repair. The surgical risk was analyzed perioperatively. The speech function and the maxillary development were also evaluated after the operation.

RESULTS

All of the cases were successfully repaired with less bleeding, quicker recovery, shorter operative time and less psychological injury. The speech function and the maxillary development were very well.

CONCLUSION

A patient, even under 3 months age, could also be a good candidates for cleft palate repairing when the general condition was good.

Developmental changes of NADPH-diaphorase positive structures in the isthmic nuclei of the chick

Nicotine adenine dinucleotide phosphate-diaphorase staining was used to study nitric oxide synthase activity and distribution in the midbrain visual structures of white leghorn chick embryos and post-hatched chickens. Enzyme staining first appeared in the isthmic region at the tenth embryonic day (E10) in the neuropil of the nucleus isthmi, pars parvocellularis. At E11 faint enzyme positivity appeared also in the nucl. isthmi pars magnocellularis, the nucl. semilunaris and the nucl. isthmo-opticus. The staining intensity of the isthmic nuclei dramatically increased between the 12.5th and the 13th days of incubation. The nucl. isthmi, pars parvocellularis showed the strongest enzyme reaction throughout embryonic life. A day before hatching all the isthmic nuclei were heavily stained, however, nicotine adenine dinucleotide phosphate-diaphorase-positive cells occurred exclusively in the nucleus isthmo-opticus. In the tectum opticum, intensely stained cells occupied the stratum fibrosum et griseum superficiale. The layer containing the projection neurons to the isthmo-optic nucleus was unstained. In the isthmic region, the intensity of staining surpassed that of the tectum and reached its maximum at E17 and then slowly decreased till the end of the experimental period (120 days post-hatched). The tractus isthmo-opticus showed nicotine adenine dinucleotide phosphate-diaphorase activity throughout the investigated period of life of the chicken, but the tractus tectoisthmo-opticus was unstained. Our results suggest that in the isthmic nuclei, nicotine adenine dinucleotide phosphate-diaphorase-positive neurons occur only in the isthmo-optic nucleus and optic tectum. The other positively stained structures are the fibers and terminals of tectal cells. In most brain areas nicotine adenine dinucleotide phosphate-diaphorase indicates nitric oxide synthase that produces nitric oxide. The transient appearance of this molecule is probably necessary for neuronal differentiation or the establishment of synaptic connections in the isthmic nuclei, and these developmental changes are under the control of the optic tectum.

Effects of GABA receptor blockade on the ventilatory response to hypoxia in hypothermic newborn piglets

Hypothermic newborn piglets have a depressed ventilatory response to hypoxia, and this may be due to an increase in CNS gamma-aminobutyric acid (GABA) levels. To evaluate the effects of GABA(A) receptor blockade on the ventilatory response to hypoxia in hypothermic piglets, 31 anesthetized paralyzed mechanically ventilated newborn piglets (2-7 d) were studied at a brain temperature of 38.5 +/- 0.5 degrees C [normothermia (NT), n = 15] or 34 +/- 0.5 degrees C [hypothermia (HT), n = 16]. The central respiratory output was evaluated by measuring burst frequency and moving time average area of phrenic nerve activity. Measurements of minute phrenic output (MPO), arterial blood pressure, heart rate, oxygen consumption, and arterial blood gases were obtained at room air and during 20 min of isocapnic hypoxia [fraction of expired oxygen (FiO2) = 0.10]. After 10 min of hypoxia, a bolus injection of 20 microL of bicuculline methiodide (BM; 10 microg) or Ringer's solution was administered into the cisterna magna over a 1-min period, and the piglets remained in hypoxia for an additional 10 min. There was an initial increase of 50 +/- 6% in MPO during the first minute of hypoxia followed by a decrease to values 24 +/- 8% above baseline at 10 min in the NT group. In contrast, in the HT group, the initial increase in MPO with hypoxia was eliminated, and, at 10 min, there was a decrease to a mean value 35 +/- 4% below baseline level (NT versus HT, p < 0.03). After administration of BM, a significant increase in MPO with hypoxia was observed in both groups compared with their placebo groups (p < 0.002 in NT-BM group, p < 0.0001 in HT-BM group). However, the magnitude of the increase in MPO during hypoxia was significantly greater in the HT group after administration of BM (NT versus HT, p < 0.0001). Changes in oxygen consumption, arterial blood pressure, heart rate, pH, partial pressure of oxygen (PaO2), and base excess with hypoxia were not different between NT and HT groups before and after the administration of BM. The cardiorespiratory response to hypoxia was not modified after administration of Ringer's solution to NT and HT placebo groups. These data suggest that the depression in hypoxic ventilatory response produced by HT is in part modulated by an increased CNS GABA concentration.

Circulating levels of glucagon-like peptide-2 in human subjects with inflammatory bowel disease

Glucagon-like peptide-2 (GLP-2) is a recently characterized intestine-derived peptide that exerts trophic activity in the small and large intestine. Whether circulating levels of GLP-2 are perturbed in the setting of human inflammatory bowel disease (IBD) remains unknown. The circulating levels of bioactive GLP-2-(1-33) compared with its degradation product GLP-2-(3-33) were assessed using a combination of RIA and HPLC in normal and immunocompromised control human subjects and patients hospitalized for IBD. The activity of the enzyme dipeptidyl peptidase IV (DP IV), a key determinant of GLP-2-(1-33) degradation was also assessed in the plasma of normal controls and subjects with IBD. The circulating levels of bioactive GLP-2-(1-33) were increased in patients with either ulcerative colitis (UC) or Crohn's Disease (CD; to 229 +/- 65 and 317 +/- 89%, P < 0.05, of normal, respectively). Furthermore, the proportion of total immunoreactivity represented by intact GLP-2-(1-33), compared with GLP-2-(3-33), was increased from 43 +/- 3% in normal healthy controls to 61 +/- 6% (P < 0.01) and 59 +/- 2% (P < 0.01) in patients with UC and CD, respectively. The relative activity of plasma DP IV was significantly reduced in subjects with IBD compared with normal subjects (1.4 +/- 0.3 vs. 5.0 +/- 1.1 mU/ml, respectively; P < 0.05). These results suggest that patients with active IBD may undergo an adaptive response to intestinal injury by increasing the circulating levels of bioactive GLP-2-(1-33), facilitating enhanced repair of the intestinal mucosal epithelium in vivo.

Electrical interaction between neurons in the pigeon isthmo-optic nucleus

The present study used brain slices to investigate interneuronal communication in the isthmo-optic nucleus in pigeons. Electrical stimulation of the isthmo-optic tract generated a transmembrane potential in isthmo-optic cells that was obtained by subtracting the extracellular potential from the intracellular potential. This transmembrane potential resulted in enhancement of excitability and/or in production of spikes in 42 (63%) cells. In most cases, proximal axons marked in brain slices by Lucifer yellow were too short to reach the stimulation site, indicating that spikes were evoked by electrical field effect or ephaptic interaction produced by nearby cells whose axons were activated by stimulation. Eleven (16%) cells discharged a spikelet, or spike that was abolished by hyperpolarizing current injection leaving a spikelet. Markings of five of these cells all indicated the presence of dye-couplings, each of which consisted of a pair of cells. Fourteen (21%) cells only produced antidromic spikes with a short and constant latency. Four of these cells were marked and their axons passed through the stimulation site, implying that their nearby cells' axons might be cut too short to be electrically stimulated or they were in a sparse-cell area. The present results provide electrophysiological and neuroanatomical evidence that both electrical field effect and electrical coupling may play important roles in interneuronal communication within the pigeon isthmo-optic nucleus. These findings are supported by anatomical arrangement of densely packed cells and their oriented dendrites in this centrifugal nucleus.

Rat McA-RH7777 cells efficiently assemble rat apolipoprotein B-48 or larger fragments into VLDL but not human apolipoprotein B of any size

Studies of truncated apoB peptides in human subjects with familial hypobetalipoproteinemia, as well as of puromycin-generated spectra of nascent apoB peptides in rat and hamster liver, suggest that a minimum size is required for N-terminal fragments of apoB to be efficiently assembled into full-sized VLDL. We report here results of experiments undertaken to examine this phenomenon in greater detail by expressing individual carboxyl-truncated human apoB constructs in McArdle cells. Thus, apoB-29, -32, -37, -42, -47, -53, -70 and full length apoB-100 were transiently expressed in rat McA-RH7777 hepatoma cells, or human apoB-31 and apoB-53 were stably expressed in the same cells, and the secreted VLDL particles were characterized by kinetic gradient ultracentrifugal flotation. Calibration with rat plasma VLDL subfractions showed that about 90 and 50%, respectively, of lipoprotein particles containing endogenous rat B-100 and B-48 floated between fractions 2;-8 of the 11-fraction gradient. This corresponds to the normal VLDL diameter range of about 47 to 28 nm, with the remaining half of rat B-48 recovered as HDL particles in the 1.1 g/ml range. In contrast, regardless of their size, only 2;-5% of any of the truncated human apoB peptides expressed in these cells was recovered in the VLDL region of the gradient. The remaining 95+% of the lipoproteins were found as high density particles; as previously found in other systems the densities of the latter were inversely related to their peptide chain-length. Furthermore, transiently expressed full-length human apoB-100 was inefficiently secreted as VLDL by these cells, with the remainder appearing as LDL-sized particles. Thus, although we showed that McA-RH7777 cells secreted endogenous rat apoB as normal-sized VLDL, we found them unsuitable for our original purpose of using human apoB fragments to further define effects of apoB size on VLDL assembly. These cells appeared unable to efficiently use any size of human apoB for that process. Pulse-labeled untransfected McA-RH7777 cells chased in the presence of puromycin did, however, show a sharp decline in VLDL assembly efficiency for endogenous nascent rat apoB peptides shorter than B-48, similar to that originally found in normal rat liver.

"Skin-CNS-bladder" reflex pathway for micturition after spinal cord injury and its underlying mechanisms

PURPOSE

A "skin-CNS-bladder" reflex pathway for inducing micturition after spinal cord injury has been established in cat. This reflex pathway which is basically a somatic reflex arc with a modified efferent limb that passes somatic motor impulses to the bladder, has been designed to allow spinal cord injured patients to initiate voiding by scratching the skin.

MATERIALS AND METHODS

The skin-CNS-bladder reflex was established in the cat by intradural microanastomosis of the left L7 ventral root (VR) to the S1 VR while leaving the L7 dorsal root (DR) intact to conduct cutaneous afferent signals that can trigger the new micturition reflex arc. After allowing 11 weeks for axonal regeneration, urodynamic, pharmacological and electrophysiological studies were conducted in pentobarbital or chloralose anesthetized animals.

RESULTS

A detrusor contraction was initiated at short latency by scratching the skin or by percutaneous electrical stimulation in the L7 dermatome. Maximal bladder pressures during this stimulation were similar to those activated by bladder distension in control animals. Electrophysiological recording revealed that single stimuli (0.3 to 3 mA, 0.02 to 0.2 msec duration) to the left L7 spinal nerve in which the efferent axons had degenerated evoked action potentials (0.5 to 1 mV) in the left S1 spinal nerve distal to the anastomosis. In addition, increases in bladder pressure were elicited by trains of the stimuli (5 to 20 Hz, 5 seconds) applied to the L7 spinal nerve. Urodynamic studies including external sphincter EMG recording demonstrated that the new reflex pathway could initiate voiding without detrusor-external urethral sphincter dyssynergia. Atropine (0.05 mg./kg., i.v.) or trimethaphan (5 mg./kg., i.v.), a ganglionic blocking agent, depressed the bladder contractions elicited by skin stimulation. The skin-CNS-bladder reflex could also be elicited after transecting the spinal cord at the L2-L3 or L7-S1 levels.

CONCLUSION

The cross-wired somato-autonomic bladder reflex is effective in initiating bladder contractions and coordinated voiding in cats with an intact neuraxis and can also induce bladder contractions after acute transection of the lumbar spinal cord. The new pathway is mediated by cholinergic transmission involving both nicotinic and muscarinic receptors. It is concluded that somatic motor axons can innervate bladder parasympathetic ganglion cells and thereby transfer somatic reflex activity to the bladder smooth muscle.

Secretion of the intestinotropic hormone glucagon-like peptide 2 is differentially regulated by nutrients in humans

BACKGROUND & AIMS

Glucagon-like peptide 2(1-33) (GLP-2(1-33)), an intestinally derived hormone, stimulates growth in rodent small and large bowel. To explore the physiology of GLP-2(1-33) secretion, we measured plasma GLP-2 levels in 6 healthy male volunteers, before and after test meals.

METHODS

Blood samples were collected over 24 hours with the subjects consuming a normal, solid mixed diet (2500 kcal) and for 4 hours after liquid test meals (400 kcal/300 mL) composed of carbohydrate, fat, or protein. All studies commenced at 9 AM. Plasma was extracted and analyzed in radioimmunoassays for N-terminal immunoreactive GLP-2 (N-IR-GLP-2; measures bioactive GLP-2(1-33)) as well as total IR-GLP-2 (T-IR-GLP-2), which includes GLP-2(1-33), GLP-2(3-33) (an inactive degradation product of GLP-2(1-33)), and the pancreatic major proglucagon fragment (an inactive precursor that contains GLP-2). Basal and nutrient-stimulated plasma samples were also analyzed by high-performance liquid chromatography to determine the levels of GLP-2(1-33) and GLP-2(3-33).

RESULTS

N-IR-GLP-2 levels were increased 2.0 +/- 0.2- to 2.8 +/- 0.5-fold 40 minutes after each mixed meal (P < 0.05-0.01) and returned to basal overnight, whereas T-IR-GLP-2 levels were increased 1.3 +/- 0.1-fold 40 minutes after breakfast only (P < 0.05). After ingestion of carbohydrate or fat alone, plasma N-IR-GLP-2 concentrations increased by 5.6 +/- 2.0- and 2.7 +/- 0.6-fold within 1 hour (P < 0.05). High-performance liquid chromatography analysis showed a relative increase in the levels of GLP-2(1-33) compared with GLP-2(3-33) (P < 0.05). Ingestion of the protein meal did not alter N-IR-GLP-2 levels, whereas T-IR-GLP-2 was increased by fat and protein (by 1.7 +/- 0. 2-fold for each, P < 0.01) but not by carbohydrate.

CONCLUSIONS

These results show that secretion of GLP-2(1-33) from the intestine is regulated in a nutrient-dependent manner in normal humans.

Reserpine modulates serotonin transporter mRNA levels in the rat brain

Despite recent advances in determining central serotonin (5-HT) function, the basic aspects by which serotonin neurotransmission is controlled and regulated are still not understood. Since the serotonin transporter (5-HTT) is involved in terminating the action of 5-HT that is released from the presynaptic nerve terminal, the regulation of 5-HTT may be an important step in controlling 5-HT neurotransmission at the synaptic cleft. The present study investigated the effects of reserpine administration on 5-HTT gene expression as well as on tryptophan hydroxylase (TPH) expression in the rat brain. Male Sprague-Dawley rats were injected with reserpine (10 mg/kg, i.p.) and sacrificed at 8 h, 3 days, 7 days or 21 days after the injection. Control rats were injected with saline and sacrificed either at 8 h or 21 days after the injection. The midbrain region was dissected, RNA was isolated and probed for 5-HTT expression using Northern Blotting. Data were analyzed using Super-Anova followed by post-hoc Dunnett's test. While mRNA levels for 5-HTT were unchanged at 8 h after reserpine, a significant decrease was noted at 3 days and 7 days (F=10; p<0.0001). 5-HTT mRNA levels returned to control levels by 21 days. In contrast, TPH expression was unaltered at all time points examined. The results of this study provide useful information regarding the role that the 5-HTT may be playing in the homeostatic control of 5-HT neurotransmission at the synapse.

Telomerase reverse transcriptase gene is a direct target of c-Myc but is not functionally equivalent in cellular transformation

The telomerase reverse transcriptase component (TERT) is not expressed in most primary somatic human cells and tissues, but is upregulated in the majority of immortalized cell lines and tumors. Here, we identify the c-Myc transcription factor as a direct mediator of telomerase activation in primary human fibroblasts through its ability to specifically induce TERT gene expression. Through the use of a hormone inducible form of c-Myc (c-Myc-ER), we demonstrate that Myc-induced activation of the hTERT promoter requires an evolutionarily conserved E-box and that c-Myc-ER-induced accumulation of hTERT mRNA takes place in the absence of de novo protein synthesis. These findings demonstrate that the TERT gene is a direct transcriptional target of c-Myc. Since telomerase activation frequently correlates with immortalization and telomerase functions to stabilize telomers in cycling cells, we tested whether Myc-induced activation of TERT gene expression represents an important mechanism through which c-Myc acts to immortalize cells. Employing the rat embryo fibroblast cooperation assay, we show that TERT is unable to substitute for c-Myc in the transformation of primary rodent fibroblasts, suggesting that the transforming activities of Myc extend beyond its ability to activate TERT gene expression and hence telomerase activity.

Transactivation-defective c-MycS retains the ability to regulate proliferation and apoptosis

Transcriptional activation by c-Myc through specific E box elements is thought to be essential for its biological role. However, c-MycS is unable to activate transcription through these elements and yet retains the ability to stimulate proliferation, induce anchorage-independent growth, and induce apoptosis. In addition, c-MycS retains the ability to repress transcription of several specific promoters. Furthermore, c-MycS can rescue the c-myc null phenotype in fibroblasts with homozygous deletion of c-myc. Taken together, our data argue against the paradigm that all of the biological functions of c-Myc are mediated by transcriptional activation of specific target genes through E box elements.

Stimulus features eliciting visual responses from neurons in the nucleus lentiformis mesencephali in pigeons

The purpose of the present study was to find out what particular stimulus features, in addition to the direction and velocity of motion, specifically activate neurons in the nucleus lentiformis mesencephali (nLM) in pigeons. Visual responses of 60 nLM cells to a variety of computer-generated stimuli were extracellularly recorded and quantitatively analyzed. Ten recording sites were histologically verified to be localized within nLM with cobalt sulfide markings. It was shown that the pigeon nLM cells were specifically sensitive to the leading edge moving at the optimal velocity in the preferred direction through their excitatory receptive fields (ERFs). Generally speaking, nLM cells preferred black edges to white ones. However, this preference cannot be explained by OFF-responses to a light spot. The edge sharpness was also an essential factor influencing the responsive strength, with blurred edges producing little or no visual responses at all. These neurons vigorously responded to black edge orientated perpendicular to, and moved in, the preferred direction; the magnitude of visual responses was reduced with changing orientation. The spatial summation occurred in all neurons tested, characterized by the finding that neuronal firings increased as the leading edge was lengthened until saturation was reached. On the other hand, it appeared that nLM neurons could not detect any differences in the shape and area of stimuli with an identical edge. These data suggested that feature extraction characteristics of nLM neurons may be specialized for detecting optokinetic stimuli, but not for realizing pattern recognition. This seems to be at least one of the reasons why large-field gratings or random-dot patterns have been used to study visual responses of accessory optic neurons and optokinetic nystagmus, because many high-contrast edges in these stimuli can activate a neuron to periodically discharge, or groups of neurons to simultaneously fire to elicit optokinetic reflex.

[A clinical study on reducing immunologic rejection in combining corneal lamellar autografting with allografting]

OBJECTIVE

To reduce the rate of immunologic rejection, corneal lamellar autografting with allografting were combined, making immune cells less attack on allograft.

METHODS

The pterygium having encroached upon the pupillary area was removed surgically, and the combination of autograft with allograft was transplanted on the peripheral and central cornea in 23 cases (24 eyes). The control group of 13 cases (13 eyes) was established in which the pterygium and dermoids were removed, and lamellar allografts were transplanted. The rate of rejection and their effects were compared.

RESULTS

The rate of transparent autograft and allograft was 100%, no rejection and recurrence of pterygium occurred in any case in the combined group, while in the control group, the rejection rate was 30.8% and recurrence rate, 20.0%.

CONCLUSION

The combination of lamellar autografting with allografting can reduce the rate of rejection and recurrence of pterygium.

Apoptosis in the developing cerebellum of the thyroid hormone deficient rat

The mechanism underlying transient reduction of cell number in the developing cerebellum have been studied for several decades. In this study we analyzed cell death by apoptosis in the developing cerebellum of euthyroid and hypothyroid rats. Results showed that in both groups the apoptotic activity is limited to the internal granular layer from postnatal (p) day 2 to day 12 in euthyroid animals, with the peak at 8 days. No apoptotic cells were detected in the cerebellum of 22 days old euthyroid rats. The level of apoptosis in the cerebellum of hypothyroid rats also reached a peak at 8 days but was four times higher than in control animals. Apoptosis in hypothyroid animals was also observed at p22 and corresponds to the value found in the time of the apoptotic peak in euthyroid cerebellum. At the age of 42 days, no apoptotic cells were found in the cerebellum of either group. Furthermore, it appears that the hormone also plays a role in the disappearance of the external germinal layer, since its presence is still apparent in 42 day old hypothyroid cerebellum. Hence, our results suggest that the deficiency of thyroid hormone (TH) not only increases, but also extends apoptosis during rat cerebellum development and affects the disappearance of the external germinal layer.

Secretoneurin and chemoattractant receptor interactions

Secretoneurin (SN) is a 33-amino acid peptide derived from secretogranin II (chromogranin C) which induces chemotaxis of monocytes but not neutrophils. In this study, we found that SN interacted with specific cell surface binding sites on human monocytes. The chemoattractants MCP-1, MCP-2 or fMLP could not compete for SN binding sites suggesting SN may bind to a novel chemotactic receptor. Additional studies showed that neither SN nor MCP-2 induced a rise in cytosolic Ca2+, and chemotaxis to SN was inhibited by cholera toxin (CT) and pertussis toxin (PT). Chemotactic desensitization studies demonstrated that fMLP, MCP-1, SN, and MCP-2 could all desensitize monocytes to subsequent SN stimulation. Our results indicate that SN binds to a cell surface receptor expressed on monocytes and activates signaling pathways which are sensitive to CT and PT.

Prothrombin deficiency results in embryonic and neonatal lethality in mice

The conversion of prothrombin (FII) to the serine protease, thrombin (FIIa), is a key step in the coagulation cascade because FIIa triggers platelet activation, converts fibrinogen to fibrin, and activates regulatory pathways that both promote and ultimately suppress coagulation. However, several observations suggest that FII may serve a broader physiological role than simply stemming blood loss, including the identification of multiple G protein-coupled, thrombin-activated receptors, and the well-documented mitogenic activity of FIIa in in vitro test systems. To explore in greater detail the physiological roles of FII in vivo, FII-deficient (FII-/-) mice were generated. Inactivation of the FII gene leads to partial embryonic lethality with more than one-half of the FII-/- embryos dying between embryonic days 9.5 and 11.5. Bleeding into the yolk sac cavity and varying degrees of tissue necrosis were observed in many FII-/- embryos within this gestational time frame. However, at least one-quarter of the FII-/- mice survived to term, but ultimately they, too, developed fatal hemorrhagic events and died within a few days of birth. This study directly demonstrates that FII is important in maintaining vascular integrity during development as well as postnatal life.

Studies on the enzymology of aldehyde dehydrogenase-2 in genetically modified HeLa cells

The Asian flush reaction is known to result from a lysine for glutamine substitution in the aldehyde dehydrogenase 2 (ALDH2) gene. This mutation was studied in HeLa cells transduced with retroviruses carrying the ALDH2E (wild-type) and ALDH2K (variant) cDNAs. The cells expressed high levels of the enzyme protein that had the same pI and enzymatic characteristics as the corresponding liver enzyme. When cells expressing ALDH2E were transduced with ALDH2K expressing retrovirus, the ALDH2 activity was reduced roughly in proportion to the amount of ALDH2K mRNA expressed, indicating a dominant suppression of activity. The half-life of the wild-type enzyme was 22 hr, while that of variant enzyme was 14 hr. The half-life of the enzyme in cells expressing both cDNAs was 13 hr, indicating that the shorter half-life of the variant was also dominant These data are consistent with a model in which the wild-type homodimers have normal activity and turnover, while the heterodimers have reduced to virtually no activity and increased turnover. The model predicts residual ALDH2 activity in heterozygotes of about 13% of that in individuals homozygous for ALDH2*1, in good agreement with experimentally determined values.

Centrifugal innervation modulates visual activity of tectal cells in pigeons

Centrifugal modulation of visual responsiveness of tectal cells by the isthmo-optic nucleus (ION) through the retina was studied in homing pigeons. Visual activity evoked by computer-generated stimuli was reduced by an average of 59% in tectal cells whose receptive fields (RFs) either overlapped with, or were close to, those of isthmo-optic cells whose activity was blocked by the injection of lidocaine through micropipettes. Activity usually recovered to 87% of pre-drug controls in 8-17 min (average 12.3 min) after stopping lidocaine injections. Those tectal cells whose RFs were far from those of ION cells did not show clear-cut changes in their visual responsiveness to isthmo-optic lidocaine application. The spatial relationship between receptive fields of tectal and isthmo-optic cells, saline controls, as well as the specificity, reproducibility and reversibility of effects of ION-injected lidocaine on tectal activity, show that this chemical action is pharmacological, not toxicological. Neuronal circuitry underlying centrifugal modulation of tectal activity by isthmo-optic cells is discussed.

[Development of the LCY-3E intelligent intracranial pressure monitor]

The LCY-3E intelligent intracranial pressure (ICP) monitor uses a microcomputer system for measurement and control. The ICP is transmitted by an air capsule, and detected by an universal high precision transducer. The problem of zero point drift during continuous ICP measurement was successfully solved and the electric safety of the instrument was greatly improved.

Fibrinogen deficiency is compatible with the development of atherosclerosis in mice

A critical role of the coagulation system in the development of atherosclerosis has been frequently postulated based on a variety of indirect observations, including the expression of procoagulants and fibrinolytic factors within atherosclerotic vessels, the presence of substantial amounts of fibrin(ogen) and fibrin degradation products within intimal lesions, the cellular infiltration and assimilation of mural thrombi into developing plaques, and the identification of high plasma fibrinogen (Fib) levels as an independent risk factor for the development of ischemic heart disease. To directly examine the role of fibrin(ogen) in atherogenesis, Fib-deficient mice were crossed to atherosclerosis-prone apolipoprotein E (apo E)-deficient mice. Both apo E-/- and apo E-/-/Fib-/- mice developed lesions throughout the entire aortic tree, ranging in appearance from simple fatty streaks to complex fibrous plaques. Furthermore, remarkably little difference in lesion size and complexity was observed within the aortae of age- and gender-matched apo E-/- and apo E-/-/Fib-/- mice. These results indicate that the contribution of fibrin(ogen) to intimal mass and local cell adhesion, migration, and proliferation is not strictly required for the development of advanced atherosclerotic disease in mice with a severe defect in lipid metabolism.

Human placenta and fetal membranes contain peptide YY1-36 and peptide YY3-36

Extracts of human term amniotic, placental, and chorion/decidua tissue contained, respectively, 4.36 +/- 2.79 (pmol/g wet wt; mean +/- S.E.M.: n = 5). 2.78 +/- 0.5 (n = 5) and 0.68 +/- 0.68 (n = 5) peptide YY (PYY)-like immunoreactivity. Using a specific PYY antiserum, gel filtration chromatography and reverse-phase high performance liquid chromatography (HLPC), amniotic, placental and fetal intestinal tissue extracts were demonstrated to contain PYY-like immunoreactivity consisting of equal amounts of PYY1-36 and PYY3-36. The presence of pancreatic polypeptide was not detected in any of the extracts. Positive immunohistochemical staining for PYY was seen in extravillous trophoblasts in the decidual septa and fetal membranes, the syncytiotrophoblast and cytotrophoblasts, amniotic epithelial cells and in maternal decidual stromal cells. Positive staining for PYY was found at the earliest date examined (9.5 weeks) and remained present throughout pregnancy to term. PYY1-36 and PYY3-36 may play important roles in human pregnancy, acting via endocrine or paracrine mechanisms.

Locations and molecular forms of PACAP and sites and characteristics of PACAP receptors in canine ileum

In canine ileum we investigated the distribution of pituitary adenylate cyclase-activating peptide (PACAP), using immunofluorescence and radioimmunoassay and the binding of 125I-PACAP-27 to membranes. Nerve profiles immunoreactive to PACAP-27, and often to vasoactive intestinal polypeptide (VIP) as well, were found in all plexi, but PACAP was present in approximately 100-fold lesser amounts than VIP. High-performance liquid chromatography analysis of deep muscular plexus (DMP) synaptosomes suggested the presence of PACAP-38, PACAP-27, and a third unidentified molecular form. High- and low-affinity 125I-PACAP-27 binding sites were found in DMP synaptosomes and circular smooth muscle (CM) plasma membranes. In competition studies with DMP membranes, high (H)- and low (L)-affinity dissociation constants (Kd) and maximal binding capacities (Bmax) were as follows: KdH = 66.9 pM, BmaxH = 101 fmol/mg; KdL = 2.18 nM, BmaxL = 580 fmol/mg protein. The binding of 125I-PACAP-27 was fast. Dissociation was slow and incomplete in the presence of unlabeled PACAP-27 but accelerated by pretreatment with guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S). GTP gamma S or cholera toxin treatment eliminated high-affinity binding in both membranes. VIP had approximately 100-fold lower affinity than PACAP-27 in both membranes. Cross-linking studies identified an approximately 70-kDa PACAP receptor in each membrane. Thus PACAP coexists with VIP in ileal enteric nerves and acts on PACAP-preferring, possibly Gs-coupled, receptors in DMP synaptosomes and CM membranes.

Regulation of cardiac alpha-myosin heavy chain gene transcription by a contractile-responsive E-box binding protein

The hemodynamic workload imposed on the heart modulates the expression of the cardiac-specific alpha-myosin heavy chain (MHC) gene. A hemodynamic responsive element (HME) has been mapped to an E box motif (CACGTG) located at position -47 of the promoter. The present studies showed that the HME is sufficient to confer contractile responsiveness to a heterologous promoter, the simian virus thymidine kinase gene, when expressed in cultured neonatal rat ventricular myocytes. Proximity of the HME to the TATA box of the alpha-MHC promoter appear necessary for high levels of basal transcription and for the four-fold induction in response to the contractile stimulus. An HME binding protein, approximately 43 kDa, was isolated from a neonatal rat ventricular myocyte cDNA library with sequence homology to the human upstream stimulatory factor-1 (hUSF1). Electrophoretic mobility shift assay showed that the in vitro translation product of the rat USF1 cDNA bound to the alpha-MHC HME motif and was recognized by an antibody to hUSF1. Overexpression of recombinant rat USF1 in spontaneously contracting cultured cardiomyocytes significantly increased activity of a cotransfected alpha-MHC promoter/luciferase reporter plasmid containing the HME motif plus core promoter elements (-40/+32), suggesting a role of rat USF1 in the contractile-mediated activation of the gene.

Secretion from cell culture of HDL and VLDL bearing apoB-33 with a large internal deletion

Rat hepatoma McA-RH7777 cells synthesize and secrete two populations of apoB-containing lipoproteins: a larger, VLDL-sized population floating in the Sf 40-150 range and a smaller, LDL and HDL-sized population. Three permanently transfected cell lines of McA-RH7777 cells secreted (in addition to the endogenous lipoproteins) lipoproteins containing 1) a carboxyl-terminally truncated human apoB-53 (2377 amino acids in length); 2) a carboxyl-terminally truncated human apoB-31 (1420 amino acids in length); or 3) an internally deleted human apoB protein, apoB-18/95, containing a total of 1490 amino acid residues, equivalent in length to an apoB33. The apoB-18/95 protein contained amino acid residues 1-782 joined to 708 residues near the C-terminus of apoB (residues 36364343). All three of the apoB peptides, apoB53, apoB-31, and apoB-18/95, were present on smaller LDL-HDL-class lipoproteins, with buoyant densities in the HDL density range. The sizes of the HDL class lipoproteins agreed with prior observations that lipoprotein core circumference is directly proportional to apoB size. As HDL containing apoB-18/95 conformed to this rule, contiguous apoB amino acid sequence is not required for the rule to be obeyed. In addition, apoB-18/95, but not apoB-31, was also present on the VLDL-sized lipoproteins even in the absence of serum or oleate supplementation. As the latter two constructs encode equally sized apoB peptides, their particular amino acid sequences rather than just overall length must determine whether they can assemble into a VLDL particle.

Growth and dissemination of Lewis lung carcinoma in plasminogen-deficient mice

Plasminogen activation has been proposed to play a critical role in cancer invasion and metastasis. The effects of complete ablation of plasminogen activation in cancer was studied by inoculation of a metastatic Lewis lung carcinoma expressing high levels of plasminogen activator into plasminogen-deficient (Plg-/-) mice and matched control mice. Primary tumors developed in all mice with no difference in the rate of appearance between Plg-/- and control mice. However, the primary tumors in Plg-/- mice were smaller and less hemorrhagic and displayed reduced skin ulceration. In addition, dissemination of the tumor to regional lymph nodes was delayed in Plg-/- mice. Surprisingly, no quantitative differences were observed in lung metastasis between Plg-/- and control mice. In addition, Plg deficiency was compatible with metastasis of the primary tumor to a variety of other organs. Nevertheless, Plg-/- mice displayed a moderately increased survival after primary tumor resection. These findings suggest that plasmin-mediated proteolysis contributes to the morbidity and mortality of Lewis lung carcinoma in mice, but sufficient proteolytic activity is generated in Plg-/- mice for efficient tumor development and metastasis.