Effect of life in a constant light environment on the course of hypertension in Dahl rats

An important goal for biobehavioral scientists is to evaluate treatments that might extend life in the presence and absence of disease. The prototypic example of such a treatment is food restriction. Importantly, we have shown that exposure to a life-long environment of constant light extends life in hamsters with severe, life-threatening heart disease. The purpose of this experiment was to determine whether constant light would also extend the life of rats with an inherited form of hypertension. Constant light neither delayed the progression of hypertension nor extended life in this model. These data suggest that constant light may have a more limited use as an experimental therapeutic modality to extend life as compared to food restriction.

Persistent plasma cholesterol elevations are produced by one or three stressor exposures in rats fed a normal laboratory diet

Typically, stress-related elevations in rat plasma cholesterol (CHOL) require preexposure to diets high in fats or cholesterol and lengthy stressor protocols. We report on two studies in which we measured plasma CHOL 22-h poststressor in rats fed Purina Laboratory Rodent Chow and exposed to 3 (3-day) or 1 (1-day) daily stressor sessions [40, 2 mA tailshocks]. In the first study, both the 3-day and 1-day groups exhibited moderately elevated morning plasma CHOL 22-h poststressor compared to nonshocked controls. Along with the groups in the first study, a second study included a restricted food control, rats transferred to the stressor environment, and rats simply transferred to an adjacent room. Neither restricted feeding nor the room transfers had an effect on morning plasma CHOL. However, the 3-day and 1-day groups again exhibited moderately elevated CHOL. Previous reports did not find elevated plasma CHOL in rats given a single stressor exposure when sampled at the end of the stressor session. Thus, the persistently elevated morning CHOL exhibited by the 1-day group may develop over time. The relatively slow development of plasma CHOL elevations may be related to the time course of stressor-induced thyroid suppression.

Effects of modulation of basic fibroblast growth factor on tumor growth in vivo

BACKGROUND

Recombinant human basic fibroblast growth factor (rHu-bFGF) is known to stimulate proliferation in some tumor cells and to modulate tumor vascularization.

PURPOSE

The purpose of this study was to examine the possible role of this agent in the development of tumors. The study was designed to determine the effects of modulating bFGF activity in vivo in tumor models from cell lines with different responses to bFGF and with different content and receptor levels of bFGF.

METHODS

Two tumor cell lines (human DLD-2 colon carcinoma and rat C6 glioma) were characterized for bFGF content and bFGF receptor levels by Western blot analysis in cultured cells and by studies of [125I]rHu-bFGF binding to sections from xenografts grown in nude mice. Tumor cell proliferation was monitored after treatment with rHu-bFGF or the DG2 or DE6 IgG monoclonal antibody to rHu-bFGF in culture and in vivo.

RESULTS

C6 cells exhibited 7800 high-affinity receptors for rHu-bFGF per cell (dissociation constant [Kd] = 46 pM), while DLD-2 cells lacked high-affinity receptors. rHu-bFGF stimulated [3H]thymidine uptake by C6 cells, but the addition of DG2 IgG prevented this stimulation; rHu-bFGF had no effect on [3H]thymidine incorporation by DLD-2 cells. C6 cells had higher levels of immunoreactive bFGF than did DLD-2 cells. The xenografts from both cell lines exhibited high-affinity [125I]rHu-bFGF binding that was concentrated on vascular-like structures. rHu-bFGF at a dosage of 0.25 mg/kg given intraperitoneally daily for 18 days caused a twofold increase in DLD-2 tumor weight but had little effect on the growth of C6 xenografts. In contrast, daily intravenous injections of DG2 IgG given to mice had no effect on DLD-2 tumor growth but reduced growth of C6 tumors by approximately 30%--a statistically significant difference.

CONCLUSIONS

The addition of exogenous rHu-bFGF or of a neutralizing antibody resulted in significant alterations in tumor growth in vivo, which were specific for tumor type and bFGF characteristics. While some of these effects may be mediated by the bFGF-responsive endothelial cells of the tumor vasculature (DLD-2 colon carcinoma), others may result from inhibition of bFGF-dependent tumor cell proliferation (C6 glioma).

IMPLICATIONS

Studies that measure tumor blood flow are necessary to confirm that these effects are mediated by changes in tumor vasculature.

Glomerular hyperfiltration in NIDDM patients without overt proteinuria

OBJECTIVE--To evaluate the frequency and correlates of glomerular hyperfiltration in NIDDM patients without overt proteinuria. RESEARCH DESIGN AND METHODS--A cross-sectional study was conducted. Seventy-one consecutive NIDDM patients attending an outpatient clinic, with Albustix-tested negative urine and a 24-h AER < 200 micrograms/min, were examined for long-term complications of diabetes. We measured their GFR (51Cr-EDTA single-injection method), 24-h AER (RIA), plasma creatinine, HbA1c, total cholesterol, triglycerides, urinary glucose, and urea. RESULTS--GFR above the upper limit of the normal range for age-matched control subjects (137.1 ml.min-1 x 1.73 m2) was present in 15 of 71 (21%) NIDDM patients. Subjects with normal and hyperfiltration did not differ in terms of age, sex distribution, BMI, duration of NIDDM, BP, AER, or frequency of long-term complications. Plasma glucose was significantly higher in subjects with hyperfiltration (mean [range]: 12.8 [4.3-18.7] vs. 8.7 [2.6-17.5] mM). HbA1c failed to reach statistical significance, although it tended to be higher in the group with hyperfiltration (10.4 [6.7-13.9] vs. 9.4 [4.2-16.5]%, P = 0.10). Age (rS -0.37, P = 0.002), FPG (rS 0.45, P < 0.0005), total cholesterol (rS -0.31, P = 0.008), and glycosuria (rS 0.40, P = 0.001) correlated significantly with GFR. In a stepwise multiple regression analysis, FPG, age, and total cholesterol emerged as significant correlates of the dependent variable GFR. CONCLUSIONS--Hyperfiltration occurred in 21% of NIDDM patients without overt proteinuria. FPG and age significant correlates of the GFR in these patients. Cholesterol is significantly (although only modestly) correlated with the GFR.

Immunolocalization of basic fibroblast growth factor to the microvasculature of human brain tumors

BACKGROUND

Microvascular proliferation, a prominent feature of tumors of the central nervous system, is a prime target for anti-cancer therapy.

METHODS

Because basic fibroblast growth factor (bFGF) plays a key role in the regulation of angiogenesis, surgical specimens from 52 human brain tumors were examined by immunocytochemical studies with a murine monoclonal antibody to bFGF. Sections from these tumors also were incubated with Ki-67 monoclonal antibody to measure the growth fraction.

RESULTS

Immunostaining for bFGF was observed in 45 of 52 (87%) neoplasms, reacting with 97% of the malignant brain tumors and 67% of benign tumors (P < 0.01). The nonreactive tumors were a medulloblastoma and 7 of 21 (33%) benign, noninvasive, slow-growing neoplasms (1 acoustic schwannoma, 3 meningiomas, 2 pituitary adenomas, and 1 cholesteatoma). The indices of proliferation (Ki-67 labeling) were lower for the 21 benign tumors (1.2 +/- 1.1%) than the 31 malignant tumors (10.3 +/- 10.5%; P < 0.001). The bFGF was immunolocalized in the tumor cell nuclei in 23 of 52 tumors (44%) and in the cytoplasm of 8 of 52 (15%) tumors. Immunostaining to bFGF was prominent in the microvascular endothelial compartment in 84% of the malignant tumors and only 52% of benign tumors (P < 0.01). Immunostaining was not present after preabsorption of the antibody with pure human recombinant bFGF.

CONCLUSIONS

The presence of bFGF predominantly within the tumor microvasculature indicates a cellular depot for this potent growth factor that mediates angiogenesis and tumorigenesis. These data support a role for bFGF in the transition from the benign to the malignant phenotype.

Structure-activity relationships of imidazo[4,5-f]quinoline partial structures and analogs. Discovery of pyrazolo[3,4-f]quinoline derivatives as potent immunostimulants

Structure-activity studies have been carried out on a series of imidazo[4,5-f]quinoline derivatives reported to have potent in vivo immunostimulatory activity. This activity has been confirmed, and subtle structure-activity relationships have been uncovered which resulted in the identification of novel analogs (pyrazolo[3,4-f]quinoline derivatives, 7a,b) with potent in vivo effects in a mouse protection model. Regioisomeric pyrazolo[4,3-f]quinoline derivatives (6a,b) were shown to be inactive. Data are presented which support the notion that the in vivo activity is mediated by an immunostimulatory mechanism.

Regulation of synovial cell growth. Coexpression of transforming growth factor beta and basic fibroblast growth factor by cultured synovial cells

OBJECTIVE

To demonstrate expression of transforming growth factor beta (TGF beta) and basic fibroblast growth factor (bFGF) by cultured rheumatoid arthritis (RA) synovial cells and to investigate their role as synovial cell mitogens.

METHODS

Polypeptide growth factors were detected and identified by immunocytochemical staining and Western blot analysis. Messenger RNA (mRNA) transcripts encoding TGF beta and bFGF were identified by polymerase chain reaction analysis. The influence of neutralizing growth factor monoclonal antibodies (MAb) on RA synovial cell growth was investigated. TGF beta bioactivity was determined by Mv1Lu assay.

RESULTS

Lysates of RA, as compared with normal, synovial cells contained greater amounts of TGF beta and bFGF. Western blot analysis identified a single TGF beta band (MW approximately 25 kd) in each of the cell lysates examined. Western blot analysis using MAb DE6 identified a doublet of bFGF bands (MW approximately 18.0 kd) in normal synovial cell lysates and 4 bFGF bands (MW approximately 18.0, 22.0, 22.6, and 25.2 kd) in RA synovial cell lysates. RA and normal synovial cells expressed mRNA transcripts encoding TGF beta 1 but not TGF beta 2, and FGF-2 (basic FGF). Additional mRNA transcripts encoding FGF-5 and FGF-7 were expressed by RA, but not normal, synovial cells in culture. In contrast to MAb 1D11.16, which caused a dose-dependent decrease in RA synovial cell growth, MAb DG2 (up to 100 micrograms/ml) had no effect on cell growth.

CONCLUSION

RA and normal synovial cells cultured in serum-free medium express TGF beta 1 and native bFGF. However, only RA synovial cells in culture express higher molecular weight isoforms of bFGF. TGF beta 1 appears to regulate synovial cell growth in vitro through an external autocrine loop. Despite expression of high-affinity bFGF receptors on cultured synovial cells, the mechanisms by which bFGF modulates synovial cell growth are unknown.

Immunoconjugates containing novel maytansinoids: promising anticancer drugs

The potential of immunoconjugates of cytotoxic drugs for the treatment of cancer has not yet been realized owing to the difficulty of delivering therapeutic concentrations of these drugs to the target cells. In an effort to overcome this problem we have synthesized maytansinoids that have 100- to 1000-fold higher cytotoxic potency than clinically used anticancer drugs. These maytansinoids are linked to antibodies via disulfide bonds, which ensures the release of fully active drug inside the cells. The conjugates show high antigen-specific cytotoxicity for cultured human cancer cells (50% inhibiting concentration, 10 to 40 pM), low systemic toxicity in mice, and good pharmacokinetic behavior.

Modulation of synovial fibroblast plasminogen activator and plasminogen activator inhibitor production by protein kinase C

Phorbol myristate acetate (PMA) added to human synovial fibroblast cultures caused a dose-dependent increase in the production of plasminogen activator inhibitor-type 1 (PAI-1). In addition, PMA inhibited endogenous and interleukin-1 (IL-1) induced plasminogen activator (PA) activity, while increasing mRNA PAI-1 levels. Other protein kinase C (PKC) activators, mezerein and teleocidin B4, caused similar effects. The simultaneous addition of the PKC antagonists, H-7 or staurosporine, prevented the inhibition of PA activity by PMA. This study shows that activation of PKC inhibits PA and stimulates PAI production in human synovial fibroblasts. These results suggest that activation of PKC may play an important role in regulating increased PA production associated with joint destruction in rheumatoid arthritis (RA).

Evolution of glomerular filtration rate in proteinuric NIDDM patients

OBJECTIVE

To evaluate, by means of a precise method, the rate of decline of glomerular filtration rate in proteinuric non-insulin-dependent diabetic (NIDDM) patients.

RESEARCH DESIGN AND METHODS

The study was comprised of seven NIDDM patients who visited an outpatient clinic and had a 24-h urinary protein excretion rate greater than or equal to 500 mg in the absence of heart failure, urinary tract infection, or other nephropathies.

RESULTS

Glomerular filtration rate (51Cr-labeled EDTA, single-injection protocol) and 24-h proteinuria (turbidimetric method) were assessed at periodic intervals (2-6 mo). Correlation of the measurements with time (Pearson's r, with Student's t test used to assess the significance, alpha = 0.05) was used to evaluate the trend of evolution of glomerular filtration rate. Renal biopsies were performed in four patients. In three of four patients, renal histopathology was consistent with the diagnosis of diabetic nephropathy (in the 4th patient measurements were not satisfactory). Neither glomerular filtration rate nor proteinuria correlated significantly with time, except in one patient who had multiple myeloma.

CONCLUSIONS

The decline of glomerular filtration rate in proteinuric NIDDM patients is different from that observed in insulin-dependent diabetic patients, which is probably much slower.

[Comparative multicenter study of bovine insulin with forms more purified of swine and human insulin in the treatment of type 1 diabetes mellitus]

A multicentric double-blind randomized study was organized to investigate the relationship between insulin antibodies and metabolic control in type I diabetics who changed from bovine insulin to monopic porcine and monocomponent human insulin. Twenty eight type I diabetic patients treated with bovine insulin (proinsulin less than 3,000 ppm) were selected. In a 6 month study, 9 patients maintained bovine insulin, 9 changed to monopic porcine insulin (proinsulin less than 10 ppm) and 10 to human insulin (proinsulin less than 1 ppm). The insulin were a gift from Biobras laboratory. The insulin antibodies (IA) were measured by an ELISA method and the metabolic control assessed by fasting blood sugar (FBS), 24 hour glucosuria and glycated protein (GP) measured by affinity chromatography method. After switching insulin therapy, IA decreased with porcine and human insulin, but increased with bovine insulin. Concerning metabolic control, only an increase of FBS with human insulin was found. In the beginning of study, there was negative correlation between IA and 24h glucosuria (rs = -0.509; p = 0.006). In conclusion, there was no improvement of metabolic control, in spite of a decrease of IA in type I diabetics treated during 6 months with less immunogenic insulin preparations.

An automated filtration assay for protein kinase C ligands

[3H]Phorbol dibutyrate ([3H]PDBu) binding to soluble mouse brain protein kinase C (PKC) was established in a 96-well microtiter plate assay. [3H]PDBu-PKC receptor complexes were rapidly aspirated from wells, filtered, and washed onto glass fiber filter mats using an automated cell harvester. Results were compared to a modification of a previously described assay in which components were incubated in tubes, and manually delivered and washed onto filters with a manifold filtration apparatus. Both 96-well plate and tube assays gave qualitatively and quantitatively similar results since: (i) [3H]PDBu binding to PKC was phosphatidylserine (PS) dependent and calcium stimulatable; (ii) the amounts of [3H]PDBu bound by filters with each technique at receptors excess were similar, 3.2 +/- 0.3 and 3.1 +/- 0.4 pmol respectively; and (iii) the affinities of [3H]PDBu for PKC were comparable; Kd's were 1.95 +/- 0.3 and 2.2 +/- 0.55 nM, respectively. The 96-well plate assay was more accurate and rapid than the tube assay. The microtiter plate assay was adapted for use with [N,N-dimethyl-3H]N,N-dimethylstaurosporine ([3H]DMS). With [3H]PDBu and [3H]DMS as ligands, the 96-well plate method was used for the rapid discrimination of agents which bound selectively at the regulatory and/or catalytic domains of PKC.

Basic fibroblast growth factor: a potential autocrine regulator of human glioma cell growth

Basic fibroblast growth factor (bFGF) is a potent mitogen and angiogenic factor. bFGF is expressed by a variety of solid human tumors and has been implicated as an autocrine regulator of tumor growth. Different solid tumor lines including glioma, colon carcinoma and melanoma were examined for intracellular immunoreactive bFGF, high- and low-affinity bFGF receptors and mitogenic response to bFGF when grown in chemically defined medium. All tumor lines contained significant levels of bFGF. In addition, all tumor lines contained subsets of five forms of immunoreactive bFGF, as well as 0.68-20 x 10(6) low affinity bFGF binding sites (Kd = 15-300 nM). Most, but not all lines exhibited high affinity bFGF receptors (Kd = 25-40 pM). Glioma cell lines were distinguished by expressing the highest levels of bFGF protein as well as the most high-affinity receptors for bFGF. Furthermore, glioma cell lines were the only tumor type mitogenically responsive to bFGF. These results indicate that glioma cells express high levels of this potent mitogen and angiogenic factor relative to human colon carcinoma and melanoma cells. The expression of bFGF and bFGF receptors by glioma cells may be related to abnormal growth and neoplastic progression in these tumors.

Characterization of specific [3H]dimethylstaurosporine binding to protein kinase C

The microbial alkaloid staurosporine is a member of a recently described family of protein kinase inhibitors. [N,N-dimethyl-3H]N-dimethylstaurosporine ([3H]DMS) was prepared from staurosporine by methylation with [3H]methyl iodide. Since staurosporine inhibits protein kinase C (PKC) most potently, the binding of [3H]DMS to this enzyme was examined. Unlike [20-3H(N)]phorbol-12,13-dibutyrate ([3H]PDBu) binding to PKC, [3H]DMS binding was not calcium or phosphatidylserine (PS) dependent. Binding was reversible, with a T1/2 of 69 min and a Koff of 0.01/min. Non-specific binding was defined by a 500-fold molar excess of staurosporine and was less than 10% of total [3H]DMS binding. Specific binding of [3H]DMS was consistent with a single class of binding sites with a Kd of 3.8 +/- 0.6 nM and a Bmax of 675 +/- 30 pmol/g tissue. In competition experiments, staurosporine inhibited [3H]DMS binding with a Ki of 4.7 +/- 0.6 nM, indicating that the two alkaloids had a similar potency for PKC. Also, unlabeled DMS and staurosporine inhibited [3H]DMS binding and PKC catalysis with equivalent potencies. Highly purified rat brain PKC bound equimolar amounts of [3H]PDBu and [3H]DMS. In contrast, crude rat brain PKC, which had been proteolysed to generate a PS and Ca2+ independent enzyme (PK-M) retained the ability to bind [3H]DMS, but not [3H]PDBu. In addition, the kinase inhibitors K-252a and H-7 [1-(5-isoquinolinesulfonyl)-2-methylpiperazine] inhibited [3H]DMS binding, whereas PDBu did not. These results indicate that [3H]DMS is a useful ligand to identify catalytic inhibitors of kinase activity and to explore their mechanisms of action.

Basic fibroblast growth factor-like activity and receptors are expressed in a human glioma cell line

Basic fibroblast growth factor (bFGF), a potent mitogen and angiogenic peptide, has been examined as an autocrine regulator of glioma cell growth. The addition of purified bovine pituitary bFGF to an established human glioma cell line, SNB-19, doubled the density of these cells in chemically defined medium. Half-maximal stimulation occurred at 8.2 ng/ml (480 pM). Also, human recombinant bFGF (hr-bFGF) significantly enhanced the growth of SNB-19 cells in soft agar. SNB-19 cells expressed both high and low affinity binding sites for hr-bFGF. These cells expressed approximately 13,000 high affinity sites/cell (Kd = 16.6 +/- 1.7 pM) and 9.5 x 10(6) low affinity sites/cell (Kd = 61.2 +/- 4.1 nM). The results of cross-linking experiments with iodinated hr-bFGF demonstrated the presence of two bands with molecular masses of 145 and 130 kDa. High affinity receptors were also demonstrated in SNB-19 tumors grown in nude mice. SNB-19 cell extracts contained mitogenic activity that eluted from heparin-agarose with high salt (1.2-2 M NaCl) and exhibited many properties normally associated with authentic bFGF. This material cross-reacted with a monoclonal antibody to hr-bFGF, comigrated with hr-bFGF by Western blot analysis, competed with 125I-hr-bFGF in a radioreceptor assay, and stimulated SNB-19 cell growth. These results indicate that a human glioma cell line both expresses and utilizes a bFGF-like growth factor. Such a factor may be an important autocrine regulator of glioma cell growth and may also facilitate its neoplastic progression.

Protein kinase C-linked inactivation of the interleukin-1 receptor in a human transformed B-cell line

The effect of tumor-promoting phorbol ester treatment on the binding of interleukin-1 beta (IL-1 beta) to specific cell surface receptors was investigated. A 1 h exposure of Raji human B lymphoma cells with the protein kinase C-activating phorbol ester, phorbol dibutyrate (PDBu), reduced IL-1 beta binding by up to 90% of control cells. This effect was dose-dependent and was not observed with 4-alpha-phorbol, an inactive tumor promoter. Analysis of 125I-labeled IL-1 beta binding to intact cells revealed that PDBu caused a 91% decrease in high-affinity cell-surface receptor number without an effect on receptor affinity. The phorbol ester response was rapid (30 min), observed both at 4 and 37 degrees C, and was preceded by the rapid translocation (t much less than 6 min) of protein kinase C (PKC) from the cytosol to the cell membrane. The PDBu-induced decrease in IL-1 beta receptor number was inhibited by prior incubation of cells for 30 min with the PKC inhibitor 1-(5-Isoquinoline sulfonyl)-2-methylpiperazine (H7). The decrease in receptor binding was not due to enhanced IL-1 beta receptor internalization or shedding into the extracellular medium, since a similar effect was observed with solubilized IL-1 beta receptor. The most likely explanation for the phorbol ester effect appears to be cell surface inactivation of IL-1 receptors. These data suggest that modulation of PKC activity could play a role in the regulation of the IL-1 beta receptor.

Subcellular distribution of protein kinase C/phorbol ester receptors in differentiating mouse keratinocytes

The activation of protein kinase C (PKC) by diacylglycerol or tumor promoters plays a pivotal role in signal transduction and subsequent activation of cellular processes. Since the activity of this enzyme is dependent on its immediate lipid domain, its relative distribution within the cell may be an important regulatory mechanism. We report here a relative decrease in PKC/phorbol ester receptor associated with the particulate fraction of mouse keratinocytes induced to differentiate by two separate systems. First, proliferating keratinocytes maintained in low Ca2+ (0.09 mM) serum-free medium were induced to differentiate rapidly by the addition of Ca2+ (1.8 mM). A 1.4-fold decrease in the percent of total phorbol receptor binding activity present in the particulate fraction and concomitant increase in binding in the cytosol fraction was evident 20 min after the Ca2+ addition. Second, in keratinocytes that differentiate over a 6 day cultivation period in serum-containing medium with Ca2+ concentration of 1.8 mM, a significant decrease in the percent of the phorbol receptor binding activity present in the particulate fraction was observed as the culture begins to differentiate on days 3 and 4. Maximal phorbol ester binding in the particulate fraction corresponded to the proliferative phase of the culture (day 2), while lower levels of PKC/phorbol ester binding to particulate fractions were noted during the early differentiative phase (days 3 and 4). Addition of the synthetic diacylglycerols 1-oleoyl-2-acetylglycerol or L-alpha-1,2 dioctanyl glycerol at 30 micrograms/ml to proliferating keratinocyte cultures induced a modest increase in two markers of terminal differentiation: cornified envelope formation and transglutaminase levels. These findings, taken together, support the hypothesis that PKC activation plays a role in the initial signalling events for keratinocyte differentiation.

[Pituitary adenomas: immunohistochemical study of 167 cases]

One hundred and sixty seven cases of pituitary adenoma were analysed using the immunocytochemical method of the Avidin-Biotin Complex (ABC), described by Hsu et al. (1981). Six pituitary anti-hormones were utilized: anti-prolactin (aPRL) at a 1:1,500 dilution; anti-growth hormone (aHGH) at a 1:4,000 dilution: anti-adrenocorticotrophic hormone (aACTH) at a 1:3,000 dilution; anti-thyrothrophic hormone (aTSH) at a 1:3,000 dilution; anti-luteinizing hormone (aLH) at a 1:1,000 dilution; and a anti-follicle-stimulating hormone (aFSH) at a 1:300 dilution. Incubation period was 14 to 16 hours at 4 degrees C. The survey of clinical, laboratory and radiological data of cases of pituitary adenomas was performed after reading the stained slides using the immunocytochemical method. Of the 167 cases of pituitary adenomas, 136 (81.4%) disclosed a positive immunoreaction to one or more anti-hormones, and the positivity index of neoplastic cells varied from 1 to 90%. The immunoreaction was positive exclusively to one anti-hormone in 80 cases (58.8%) and to two or more anti-hormones in 56 cases, and the association most frequently found was between both aPRL and aHGH. The positivity to the immunoreaction was distributed as follows: -100 cases were positive for aPRL, exclusively in 4 cases; -65 cases were positive for aHGH, exclusively in 22 cases; -31 cases were positive for aACTH, exclusively in 8 cases; -5 cases were positive for aTSH, exclusively in one case; -one patient presented an adenoma positive to aLH and another patient to aFSH.

Inhibition of protein kinase C activity promotes the neurotrophic action of epidermal and basic fibroblast growth factors

In primary neuronal cultures the activation of protein kinase C (PKC) by tumor-promoting phorbol esters blocked growth factor-induced neuronal survival and neurite extension. Depletion of PKC markedly facilitated both epidermal growth factor and basic fibroblast growth factor-inducible neurite extension. Inhibition of PKC by H-7 also stimulated neurite extension. These results suggest that down-regulation of PKC in neurons may be required for trophic factor action.

Plasminogen activator and inhibitor activity in human glioma cells and modulation by sodium butyrate

The activity of the serine protease plasminogen activator (PA), which correlates with tumorigenicity and metastatic capacity, was examined using the 125I-labeled fibrin plate assay in cell extracts from four human glioma lines as a function of growth in vitro. Cell-associated inhibitory activity to plasmin and urokinase-type PA was also measured concurrently. The relative PA activities differed markedly among the lines, whereas inhibitory activities did not. Two lines, SNB-19 and SNB-75, exhibited maximal PA activities (1-6 m Plough units/micrograms protein) as cultures approached confluence, whereas two other lines, SNB-56 and SNB-78, expressed low PA activity at all times (less than 0.2 m Plough units/micrograms protein). The PA of SNB-19 cell extracts was predominantly urokinase-type PA. In addition to having the highest PA levels, SNB-19 and SNB-75 were the most clonogenic in soft agar and tumorigenic in nude mice. In contrast, SNB-56 and SNB-78 were poorly clonogenic in soft agar and were not tumorigenic in nude mice. Measured directly, inhibitory activities to plasmin, urokinase-type PA, and tissue-type PA were detected in SNB-19 (high PA) and SNB-56 (low PA) cell extracts. However, there were no qualitative or quantitative differences in inhibitor effects between SNB-19 and SNB-56 suggesting that the differences in PA activity between these lines resulted from changes in PA activity and were not due to differential plasminogen activator inhibitor effects. The ability of the differentiating agent sodium butyrate (NaB) to modulate total PA activity was also examined. Peak SNB-19 cell PA activity was decreased in a concentration (Ki, 0.75 mM) and time-dependent manner by the addition of nontoxic amounts of NaB. The dose-dependent decrease in PA activity induced by NaB was most likely due to an effect on PA itself, since the action of inhibitor on urokinase was unchanged in response to NaB. These results suggest that net cellular PA activity in glioma cells is a balance between relative PA activity and inhibitor(s) effects and that this balance can be modulated by sodium butyrate.

Effect of protein-restricted diet on renal response to a meat meal in humans

To study the influence of preceding dietary protein intake on the renal response to a protein meal we examined renal hemodynamic and excretory responses to a meat meal in six normal human subjects either taking their normal-protein diet (NPD, 75 +/- 5 g/day) or after 3 wk of a low-protein diet (LPD, 43 +/- 3 g/day; P less than 0.005). Glomerular filtration rate (GFR) was lower on LPD than on NPD (107 +/- 7 vs. 124 +/- 5 ml X min-1 X 1.73 M-2, respectively; P less than 0.01), as was renal plasma flow (RPF) (NPD, 666 +/- 44; LPD, 605 +/- 43 ml X min-1 X 1.73 M-2; P less than 0.05). Filtration fraction (FF) was not different (NPD, 0.19 +/- 0.01; LPD, 0.18 +/- 0.01). Urinary excretion of albumin was also lower after LPD than NPD (2.1 +/- 0.5 vs. 4.2 +/- 0.8 micrograms/min; P less than 0.05). After an 80-g protein meat meal, GFR rose to a ceiling significantly higher on NPD than on LPD (132 +/- 4.8 vs. 120 +/- 5.2 ml X min-1 X 1.73 M-2; P less than 0.02), even though the percent changes were greater on LPD than on NPD (12.7 +/- 3.3 vs. 6.6 +/- 1.5%, respectively; P less than 0.05). There was a rise in RPF that was entirely attributable to a fall in renal vascular resistance, and FF did not change. On both diets, oral protein loading produced a 200-300% increase in the urinary excretion and fractional clearance of albumin and IgG, but failed to alter that of beta 2-microglobulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary composition and renal function in healthy subjects

Increments in dietary protein intake can increase glomerular filtration rate (GFR) in humans, and the glomerular hyperfiltration induced by high protein intake has been incriminated in the progression of glomerulosclerosis related to age and a number of renal diseases. GFR (as 51Cr-EDTA clearance) was measured in 18 vegans, 16 lactovegetarians and 18 omnivorous control subjects, matched for age. Omnivores ate significantly more total protein and protein of animal origin than the other two groups. Vegetable protein comprised 100% of the vegans' daily protein intake and 64% of the lactovegetarians', both significantly higher than the omnivores' (32%). Vegans and lactovegetarians also ate more carbohydrate and fibre than omnivores, although fat intake was similar. Mean GFR was significantly lower in the vegans than in the omnivores (100 +/- 13 vs. 113 +/- 16 ml/min/1.73 m2; p less than 0.04) and was intermediate in the lactovegetarians (105 +/- 16 ml/min/1.73 m2). Omnivores had significantly higher mean urinary albumin excretion rate (p less than 0.05) than vegans, and higher mean diastolic blood pressure than both vegans and lactovegetarians (p less than 0.01). The vegan diet is associated with glomerular and systemic haemodynamic changes which may be beneficial in the prevention of glomerular sclerotic changes in health and disease.

Leptomeningeal carcinomatosis presenting as eosinophilic meningitis

The case of a 67-year-old man with underlying carcinomatous meningitis who presented with meningismus and cerebrospinal fluid (CSF) eosinophilia is reported. CSF eosinophilia can reflect a number of underlying conditions; however, carcinomatous meningitis is not generally considered. In this case, studies for bacterial, fungal and parasitic agents were negative. Cytologic examination of a lumbar puncture specimen revealed malignant epithelial cells in an inflammatory background. When unexplained eosinophilia is found in the CSF, a thorough search for coincident meningeal carcinomatosis should be undertaken.

Increased capillary endothelial cell protease activity in response to angiogenic stimuli in vitro

Bovine capillary endothelial (BCE) cells produce increased amounts of the proteases plasminogen activator (PA) and latent collagenase when cultured in the presence of the following preparations which are known to contain angiogenic activities: bovine retinal extract, mouse adipocyte conditioned medium, and human hepatoma cell lysate. These preparations stimulated both BCE cell PA and collagenase activities in a dose-dependent manner. Both activities were increased to about the same level by these preparations as by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate. Mitogens that are not angiogenic, such as insulin, epidermal and fibroblast growth factors, and endothelial cell growth supplement, had no effect on BCE cell PA and collagenase activities. Two of the angiogenic preparations (retinal extract and mouse adipocyte-conditioned medium) had no effect on PA activity in endothelial cells derived from bovine aortae (BAE cells). The angiogenic preparations had little (human hepatoma cell lysate, mouse adipocyte-conditioned medium) or no (bovine retinal extract) effect on BAE cell collagenase activities. In the bovine system, the induction of high levels of both PA and collagenase activities by angiogenic preparations is limited to capillary endothelial cells.

Down-regulation of epidermal growth factor receptor correlates with plasminogen activator activity in human A431 epidermoid carcinoma cells

Human A431 epidermoid carcinoma cells in culture exhibit epidermal growth factor (EGF)-induced "down-regulation" of cell-surface and total cellular (Triton X-100 extractable) EGF receptors caused entirely by an enhanced rate (4-fold) of receptor inactivation [Krupp, M. N., Connolly, D. T. & Lane, M. D. (1982) J. Biol. Chem. 257, 11489-11496]. The following observations show that this enhanced rate of EGF receptor inactivation is closely correlated with an increased cellular activity of plasminogen activator (PA), a serine protease. First, EGF-induced down-regulation of cell-surface and total cellular EGF receptors and the concomitant increase in cellular PA activity occur with identical kinetics, the t 1/2 for both processes being 3-3.5 hr. Second, the EGF dose-response curves for down-regulation of total cellular EGF receptor and increased PA activity are similar. The EGF concentrations for half-maximal responses of both processes are 10-15 nM and 20 nM, respectively. Third, the removal of EGF from previously down-regulated cells results in the recovery of total cellular EGF binding activity with a concurrent loss of cellular PA activity. Fourth, blocking PA synthesis or activity with cycloheximide or dexamethasone prevents down-regulation of the EGF receptor. Fifth, the addition of leupeptin, an inhibitor of PA and plasmin action, blocks EGF-induced receptor down-regulation as well as the increase of PA activity. That EGF receptor down-regulation is independent of plasminogen per se in the culture medium suggests that PA-mediated events may initiate the rapid inactivation of the EGF receptor that occurs during down-regulation.

Plasminogen activator and collagenase production by cultured capillary endothelial cells

Cultured bovine capillary endothelial (BCE) cells produce low levels of collagenolytic activity and significant amounts of the serine protease plasminogen activator (PA). When grown in the presence of nanomolar quantities of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), BCE cells produced 5-15 times more collagenolytic activity and 2-10 times more PA than untreated cells. The enhanced production of these enzymes was dependent on the dose of TPA used, with maximal response at 10(-7) to 10(-8) M. Phorbol didecanoate (PDD), an analog of TPA which is an active tumor promoter, also increased protease production. 4-O-methyl-TPA and 4alpha-PDD, two analogs of TPA which are inactive as tumor promoters, had no effect on protease production. Increased PA and collagenase activities were detected within 7.5 and 19 h, respectively, after the addition of TPA. The TPA-stimulated BCE cells synthesized a urokinase-type PA and a typical vertebrate collagenase. BCE cells were compared with bovine aortic endothelial (BAE) cells and bovine embryonic skin (BES) fibroblasts with respect to their production of protease in response to TPA. Under normal growth conditions, low levels of collagenolyic activity were detected in the culture fluids from BCE, BAE, and BES cells. BCE cells produced 5-13 times the basal levels of collagenolytic activity in response to TPA, whereas BAE cells and BES fibroblasts showed a minimal response to TPA. Both BCE and BAE cells exhibited relatively high basal levels of PA, the production of which was stimulated approximately threefold by the addition of TPA. The observation that BCE cells and not BAE cells produced high levels of both PA and collagenase activities in response to TPA demonstrates a significant difference between these two types of endothelial cells and suggests that the enhanced detectable activities are a property unique to bovine capillary and microvessel and endothelial cells.

Relationship of the Valsalva ratio to autonomic neuropathy and other complications of diabetes mellitus

1. The Valsalva ratios (VR) of 48 diabetic patients and 48 normal individuals matched by age and sex were compared in order to examine the relationship between VR and the prevalence and severity of retinopathy, neuropathy and nephropathy, which are chronic complications of diabetes mellitus. 2. Diabetic patients without clinical evidence of neurological damage had the same VR (1.95 +/- 0.09) as the matched control group (1.95 +/- 0.14). Diabetic patients exhibiting some evidence of diabetic neuropathy showed VR values lower than their control groups (1.58 +/- 0.07 vs. 1.81 +/- 0.7), whereas patients with symmetric sensitive polyneuropathy plus autonomic neuropathy had the lowest VR scores (1.16 +/- 0.04 vs. 1.86 +/- 0.14). 3. An inverse relationship was shown between VR and the prevalence of retinopathy and nephropathy and the duration of diabetes mellitus. Low VR values correlated well with the prevalence and severity of complications. 4. It is concluded that the Valsalva ratio is an effective indicator of autonomic neuropathy.

T3 hyperthyroidism and thyroid cancer

The authors present an unusual case of T3 hyperthyroidism caused by a well-differentiated thyroid follicular carcinoma and its large skull metastasis. They suggest iodine deficiency as being the single major factor in the aetiology of both disorders.

The effect of avian retroviruses on limb bud chondrogenesis in vitro

Mesenchymal cells isolated from stage 24 embryonic chicken limb buds were infected with the temperature-sensitive transformation mutants of Rous sarcoma virus tsNY68, tsNY10 and tsLA25 at the nonpermissive temperature for transformation (41 degrees C). Virus infection greatly inhibited subsequent limb bud chondrogenesis under nontransforming conditions, as indicated by a reduction in the rate of 35SO4 incorporation into cell-associated proteoglycans. The inhibition of chondrogenesis was directly related to the percentage of cells infected with tsNY68 at 41 degrees C. The observed inhibition of chondrogenesis was independent of src gene expression since this effect was also caused by many viruses which lack the src gene, including the leukosis viruses RAV-1, RAV-2 and MAV-2(0); the src deletion mutant RSVtd107; and the reticuloendotheliosis viruses REV-T and SNV. Infection of mesenchymal cells with tsNY68 under nontransforming conditions did not cause changes in parameters such as the rate of thymidine incorporation, total cell DNA and total cell protein. Infection with tsNY68 at 41 degrees C resulted in altered kinetics of 35SO4 incorporation into cell-associated proteoglycans and a corresponding reduction in 35SO4-labeled proteoglycans extracted from the cell layer. There were no apparent quantitative effects on the rate of accumulation of proteoglycans in the culture medium. The proteoglycans extracted from the cells and the collected medium of tsNY68-infected cultures were smaller than those of uninfected cultures, as shown by agarose gel chromatography.

Intraventricular 2-deoxyglucose, glucose, insulin, and free fatty acid mobilization

The possibility of eliciting changes in the activity of lipomobilizing centers in the rat central nervous system was investigated by injecting glucose or substances that affect glucose metabolism directly into the cerebrospinal fluid of conscious, unrestrained rats. Intracerebroventricular administration of minute amounts of 2-deoxyglucose to fed rats induced a rapid increase in the concentration of plasma free fatty acids (FFA) without affecting plasma insulin levels. Furthermore, small amounts of either glucose or insulin injected intraventricularly reduced the increased plasma FFA levels of normal fasted rats without affecting the glycemia or plasma insulin levels in these animals. In diabetic rats, the increased levels of plasma FFA were not affected by intraventricular administration of glucose, but clearly decreased after intraventricular insulin. The results suggest that the lipomobilizing centers are insulin sensitive and that their activity is modulated by the rate of glucose uptake, rather than by external hexose concentration. The data are also consistent with our previous hypothesis of a direct control of the sympathetic tonus of adipose tissue by these centers.

Further evidence for a central regulation of free fatty acid mobilization in the rat

Previous studies have shown that anterior hypothalamic deafferentation in rats completely suppresses the increase in plasma free fatty acid (FFA), but not the hyperglycemia induced by administration of 2-deoxyglucose, suggesting a specific central regulation of FFA mobilization. The physiological importance of this finding was further investigated by examining in deafferented rats the response to several stimuli that modify the rate of lipomobilization in normal rats. The results show that the hypothalamic lesion interferes with FFA mobilization mainly when increased sympathetic activity is required: during cold exposure or forced muscular activity, and after insulin-induced hypoglycemia or a relatively long period of fasting. Changes in blood sugar responses, when observed, could be interpreted as secondary to an initial block in FFA mobilization. The data support our hypothesis that there are areas in the central nervous system sensitive to glycopenia and activated in situations requiring rapid mobilization of metabolic reserves that can specifically influence FFA mobilization through an activation of the sympathetic fibers of adipose tissue.