Non-insulin-dependent diabetes mellitus complicated with idiopathic hypoparathyroidism

We report a case of non-insulin-dependent diabetes mellitus (NIDDM) complicated with idiopathic hypoparathyroidism. A 74-year-old male was hospitalized because of diplopia. He was revealed to have NIDDM. The levels of serum Ca and intact-PTH were 6.3 mg/dl and < 5 pg/ml, respectively. Brain computed tomography revealed abnormal calcification in the cerebral basal ganglia and the cerebellum. After recovery from hypocalcemia, the endogenous insulin secretion was normalized. It is suggested that the pathogenesis of NIDDM in this patient may have been related to an insulin secretory defect as a result of hypocalcemia in addition to the hereditary risk.

A case report of colonic ileus due to eosinophilic nodular lesions caused by Gnathostoma doloresi infection

Gnathostomiasis is primarily a disease of the skin characterized as creeping eruption or mobile erythema. However, larval Gnathostoma sometimes migrate into an unexpected site to elicit serious illness. Here we describe a case of colonic ileus caused by Gnathostoma doloresi. The patient was a 57-year-old man living in Miyazaki Prefecture, Japan, which is known as an area endemic for this parasite. One week after having eaten a few slices of the flesh of a snake (Agkistrodon halys), he developed severe abdominal pain. An abdominal radiograph revealed multiple gas-fluid levels with a distended bowel of an inverted U shape. A barium enema revealed a tumor in the ascending colon near the hepatic flexure that was surgically removed by simple colonic resection. An oblique section of a parasite surrounded by massive infiltration of eosinophils was found by postoperative histopathologic examination. The entire body of the advanced third-stage larva of G. doloresi was dissected from a specimen-embedded paraffin block.

Characterization of the 5'-flanking region and chromosomal assignment of the human brain natriuretic peptide gene

Brain natriuretic peptide (BNP) is a cardiac hormone that occurs predominantly in the ventricle, and synthesis and secretion of BNP are greatly augmented in patients with congestive heart failure and in animal models of ventricular hypertrophy. In order to elucidate the molecular mechanisms underlying the human BNP gene expression in the heart, the human BNP gene was isolated from a size-selected genomic minilibrary. The 1.9-kb human BNP 5'-flanking region (-1813 to +110) contained an array of putative cis-acting regulatory elements. Various lengths of the cloned 5'-flanking sequences were linked upstream to the bacterial chloramphenicol acetyltransferase (CAT) gene, and their promoter activities were assayed. The 1.9-kb promoter region showed a high-level CAT activity in cultured neonatal rat ventricular cardiocytes. When the CT-rich sequences (-1288 to -1095) were deleted, the high-level activity was reduced to approximately 30%. The 399-bp BNP 5'-flanking region (-289 to +110) showed approximately 10% activity of the 1.9-kb region. Furthermore, using human-rodent somatic hybrid cell lines, the BNP gene was assigned to human chromosome 1, on which the atrial natriuretic peptide gene is localized. The present study leads to a better understanding of the molecular mechanisms for the human BNP gene expression in the heart.

Clinicopathological study of minimum-sized hepatocellular carcinoma: an approach to the definition of early hepatocellular carcinoma

Clinicopathologic examination of 33 nodules from 23 cases of minimum-sized hepatocellular carcinoma (HCC), less than 15 mm in diameter, was carried out by imaging and clinical follow up. On ultrasound (US), 16 hypoechoic nodules (48%) and 15 hyperechoic nodules (45%) on angiography 7 tumour stains (21%) and on computerized tomography (CT) 3 low density nodules (9%) were detected. Of 27 nodules on lipiodol CT (LpCT), 7 lipiodol-deposited nodules (26%) were detected. Of 16 nodules on CO2US angiography (US-angiography), 7 hypervascular (44%), 5 hypovascular (31%) and 4 isovascular nodules (25%) were detected. Of 13 nodules on CT during arterial portography (CTAP), 7 perfusion defect nodules (54%) were detected. The nodules were graded according to the Edmondson & Steiner Classification. Three nodules were resected; grossly, two were not distinct and one was poorly demarcated. Histologically, they were highly differentiated with irregularly-thin trabecular-patterned HCC where portal triads were detected. Cancer cells invaded the non-cancerous liver cells by replacement, and the border between the cancerous and non-cancerous regions was unclear; the latter region manifested chronic hepatitis or liver cirrhosis without hyperplasia. Minimum-sized HCC is characteristically hypovascular in arterial and portal supply of blood, of multicentric origin and of a well-differentiated pattern. Because the three resected nodules did not damage the liver acinus structure, they were considered to be an early stage of HCC.

Quantitation of hepatitis C viral RNA in liver and serum samples using competitive polymerase chain reaction

AIMS

To investigate whether the amount of hepatitis C viral RNA (HCV-RNA) in liver and serum can predict the effectiveness of interferon treatment in patients with chronic hepatitis C.

METHODS

The amount of HCV-RNA in frozen liver tissues and sera of 22 patients with chronic hepatitis C was determined before and after interferon alfa treatment by the competitive reverse transcriptional polymerase chain reaction method.

RESULTS

Patients with small amounts of HCV-RNA in serum before treatment showed a significantly more effective response to interferon treatment. After treatment, HCV-RNA disappeared from both the liver and serum of all patients who sustained complete response (n = 11); in contrast, HCV-RNA decreased but persisted in the liver of all those who relapsed after cessation of treatment (n = 11).

CONCLUSIONS

The elimination of hepatitis C virus from the liver as well as from the serum seems to be essential for sustained remission. The quantitation of HCV-RNA in liver biopsy specimens obtained after treatment would be a highly accurate predictor of whether relapse is likely to occur.

Immunological analysis of inhibition of lung metastases by fucoidan (GIV-A) prepared from brown seaweed Sargassum thunbergii

The antimetastatic effect of GIV-A (fucoidan) and/or 5-FU was examined in an experimental model of lung metastases induced by Lewis lung carcinoma in mice. Injection of GIV-A i.p. after removal of the implanted primary tumor inhibited the development of lung metastases. Combination treatment with GIV-A and 5-FU inhibited significantly the lung metastases. The number of peritoneal macrophages, total cells and macrophages in the lung increased in mice treated with GIV-A. Binding of the third component of complement (C3) cleavage products (C3b) to the C3 receptor on peritoneal macrophages after i.v. injection of GIV-A was enhanced, as shown by the fluorescent antibody technique. Lung metastases were inhibited by i.v. injection of peritoneal macrophages activated with GIV-A. GIV-A depressed aniline hydroxylase and aminopyrine demethylase activities of the hepatic microsomal drug-metabolizing system in tumor-bearing mice. Moreover, the concentration of 5-FU in the tissues (lung, liver, kidney, spleen and blood) was increased significantly by coadministration of GIV-A. The picryl chloride-induced delayed type hypersensitivity (PC-DTH) response in mice was depressed after the implantation of tumor and treatment with 5-FU. GIV-A restored the suppression of PC-DTH by 5-FU, but did not increase the PC-DTH of normal mice. GIV-A not only enhanced the degree of spleen cell-mediated sheep red blood cell (SRBC) hemolysis (quantitative hemolysis of SRBC), the indexes of the spleen and thymus and the number of spleen cells, but also restored the suppressive effect of 5-FU. In the group receiving GIV-A, the percentages of splenic Thy1.2-, L3T4- and asialo GM1-positive cells were significantly increased as compared with the tumor-bearing mice treated with saline. Furthermore, the L3T4+/Lyt2+ ratio showed a tendency to increase, and the Lyt2+/Thy1.2+ ratio was decreased. These results suggest that the antitumor effect of GIV-A may be correlated with the changing pattern of the Thy1.2-, L3T4- and asialo GM1-positive cells, C3 activation, macrophage activation and depression of the hepatic microsomal drug-metabolizing system. These findings raise the possibility that GIV-A may have clinical value in the prevention of cancer metastasis.

Rapid transcriptional activation and early mRNA turnover of brain natriuretic peptide in cardiocyte hypertrophy. Evidence for brain natriuretic peptide as an "emergency" cardiac hormone against ventricular overload

We previously demonstrated that brain natriuretic peptide (BNP) is a cardiac hormone mainly produced in the ventricle, while the major production site of atrial natriuretic peptide (ANP) is the atrium. To assess the pathophysiological role of BNP in ventricular overload, we have examined the gene expression of BNP, In comparison with that of ANP, in a model of cardiac hypertrophy using cultured neonatal rat ventricular cardiocytes. During cardiocyte hypertrophy evoked by endothelin-1, Phenylephrine, or PMA, the steady state level of BNP mRNA increased as rapidly as the "immediate-early" induction of the c-fos gene expression, and reached a maximal level within 1 h. Actinomycin D, a transcriptional inhibitor, completely diminished the response, while the translational blocked with cycloheximide did not inhibit it. In contrast, ANP mRNA began to increase 3 h after the stimulation, and accumulated during cardiocyte hypertrophy. The BNP secretion from ventricular cardiocytes was also stimulated, more rapidly than the ANP secretion. Furthermore, the turnover of BNP mRNA was significantly faster than that of ANP mRNA, being consistent with the existence of AUUUA motif in the 3'-untranslated region of BNP mRNA. These results demonstrate that the gene expression of BNP is distinctly regulated from that of ANP at transcriptional and posttranscriptional levels, and indicate that the characteristics of the BNP gene expression are suitable for its possible role as an " emergency" cardiac hormone against ventricular overload.

Hamster alpha 1B-adrenergic receptor directly activates Gs in the transfected Chinese hamster ovary cells

A prototypic Ca(2+)-mobilizing hormone receptor, alpha 1-adrenergic receptor (alpha 1AR), stimulates cAMP accumulation. The mechanism underlying this phenomenon was previously suggested to be secondary to phosphatidylinositol hydrolysis-protein kinase C activation in some cells. We transfected Chinese hamster ovary (CHO)-K1 cells with hamster alpha(1B)AR cDNA and isolated cells stably expressing alpha(1B)AR (CHO alpha 1B cells). We investigated the molecular mechanism underlying the alpha 1AR-mediated cAMP production in the CHO alpha 1B cells. Norepinephrine (NE) stimulated intracellular calcium mobilization and cAMP production through alpha(1B)AR. Pretreatment with a phospholipase C inhibitor, U-73,122 (10 microM), abolished the NE-induced intracellular calcium response, whereas it did not affect the NE-stimulated cAMP production. Treatment with various agents (protein kinase C inhibitors, calcium ionophore, cyclo-oxygenase inhibitor, or pertussis toxin) had little effect on the NE-induced cAMP production. The parent CHO and CHO alpha 1B cells contained similar amounts of Gs alpha (42 and 45 kDa, respectively), as detected with immunoblot analysis, and exhibited similar extents of cAMP synthesis with cholera toxin and forskolin. Adenylyl cyclase activity in the CHO alpha 1B cell membranes was also enhanced by NE. Furthermore, incubation of CHO alpha 1B cell membranes with antiserum directed against the carboxyl-terminal portion of Gs alpha inhibited the NE-stimulated adenylyl cyclase activity. Taken together, the results indicate that the alpha(1B)AR-mediated cAMP synthesis in CHO alpha 1B cells reflects direct stimulation of Gs-adenylyl cyclase. Therefore, the alpha 1AR-stimulated cAMP production observed in some native tissues may involve the multiple mechanisms of the direct activation of Gs-adenylyl cyclase and a secondary effect through activation of phosphatidylinositol hydrolysis.

[Chemohyperthermic peritoneal perfusion and subtotal peritonectomy for peritonitis carcinomatosa in gastroenteric cancer]

A new operative procedure, called subtotal peritonectomy (SP), in combination with chemohyperthermic peritoneal perfusion, was developed for the treatment of peritonitis carcinomatosa in gastrointestinal cancer. SP includes resection of primary lesion, colon, small bowel, spleen, and gall bladder and parietal peritonectomy. Six patients with gastric cancer and two patients with colon cancer underwent these procedures. A great deal of discharge from the peritoneal cavity, an increase in systemic vascular resistance index, and a decrease in central venous pressure represented much decrease in circulatory volume on days 1 to 2 postoperatively. This state improved at 3 to 4 days after operation. Histopathological study revealed multiple peritoneal seedings with negative surgical margins in all patients. There were no related deaths though bleeding, perforation, and abscess occurred in two patients each. One patient died of peritoneal recurrence after one year, but the other have survived.

The complete amino acid sequence of chum salmon stanniocalcin, a calcium-regulating hormone in teleosts

Stanniocalcin (STC) is a hypocalcemic hormone secreted from the corpuscles of Stannius of bony fish. Chum salmon STC was isolated in pure form by ion-exchange chromatography and reversed phase high performance liquid chromatography following ethanol-ammonium extraction of the tissues. A cDNA was cloned from cDNAs of the tissue by the PCR method using two primers corresponding to the N- and C-terminal amino acid sequence of the hormone. Sequence analysis of the protein and the cDNA revealed that chum salmon STC is a homodimer, and that the monomer consists of 179 amino acids including 11 half-Cys residues and one N-linked glycosylation site, which is 44 residues smaller at the C-terminal region than the sequence deduced from coho salmon STC cDNA.

Young borderline hypertensives are hyperreactive to mental arithmetic stress: spectral analysis of R-R intervals

To investigate whether sympathetic tone and its reactivity to stress are increased in borderline hypertension, we compared pressor and autonomic nervous responses to mental arithmetic stress in male borderline hypertensives (BH) and normotensive volunteers (NT). Three age groups, 30, 40 and 50-year-old groups, which included 30 to 39, 40 to 49 and 50 to 59-year-old subjects, were studied. Fractional LF (%LF), fractional HF (%HF) and L/H, obtained from the power spectrum of R-R intervals, were used as indices of autonomic nervous function. Baseline autonomic nervous indices did not differ between NT and BH of any age group. Blood pressure rose higher during mental arithmetic stress in 50 than in 30-year-old NT but not in comparable age groups of BH. Pressor responses were augmented in BH compared to NT only in the 30-year-old group. However, the differences were not significant when pressor responses were expressed as percent increases in blood pressure. Both %L and L/H increased during arithmetic stress. The increase in %L did not differ between NT and BH but that in L/H (% delta L/H) was larger in 50 than in 30-year-old NT. % delta L/H was larger in BH than in NT only in the 30-year-old group. These findings suggest that both pressor and autonomic nervous responses to metal arithmetic stress were altered by aging and augmented in BH compared to NT in the 30-year-old group.

[Primary pulmonary alveolar proteinosis--clinical observation of 68 patients in Japan]

The clinical features of 68 Japanese patients (53 men and 15 women; mean age 44 years) with primary pulmonary alveolar proteinosis were reviewed. Pulmonary alveolar proteinosis was diagnosed from histologic findings after open lung biopsy (n = 7) or transbronchial lung biopsy (n = 61). Major symptoms were a dry cough (24.2%) and dyspnea or shortness of breath on exertion (51.5%), but one third of the patients were asymptomatic. Crackles were audible in 30% of the patients, but clubbing (6%) and cyanosis (4%) were rare. Ten patients had been occupationally exposed to dust. Slightly less than half (46%) of the patients first presented with symptoms, and the remainder (54%) first presented with abnormal pulmonary infiltrates seen on chest roentgenograms taken during general health examinations. Many patients had abnormally high levels of LDH and CEA in serum (62% and 63%, respectively). Restrictive pulmonary dysfunction (%VC < 80%) was seen in 31% of the patients, an abnormally low DLco (%DLco < 70%) was seen in 62%,m and hypoxemia (PaO2 < 80 mmHg) was seen in 67%. Arterial blood gas tension was closely correlated with the severity of disease in these patients. Chest roentgenograms usually showed bilateral symmetric alveolar infiltrates, mainly distributed from hilar areas toward the pleura, but on CT scans many of the shadows were mixed with alveolar and interstitial infiltrates of various extent along the pulmonary arteries and bronchi. There was no apparent relation between chest roentgenographic findings and chest CT findings in these patients. Neither the extension nor other characteristics of shadows in the chest roentgenograms and chest CT scans were closely related to symptoms, laboratory data, or pulmonary function in these patients. Symptoms were alleviated and chest roentgenographic findings improved in 82% of the 51 patients who underwent therapeutic bronchoalveolar lavage, and in 94% of the 17 patients who did not undergo that procedure. In patients who underwent therapeutic bronchoalveolar lavage and also in those who recovered spontaneously, both diffusing capacity and blood gas values improved significantly. When compared to the patients who did not undergo therapeutic bronchoalveolar lavage, significantly more of those who did undergo that procedure has initial PaO2 values below 60 mmHg, and fewer of them had values greater than 80 mmHg. Thus, a PaO2 below 60 mmHg may be an indication for therapeutic bronchoalveolar lavage in patients with this disease. During the follow-up period (mean 5 years, range 2 months to 23 years), four patients had pneumothorax and none died of pulmonary alveolar proteinosis.

Different effects of traditional Chinese medicines containing similar herbal constituents on prednisolone pharmacokinetics

Three major traditional Chinese medicines (TCM), Sho-saiko-To, Saiboku-To, and Sairei-To, consist of similar herbal prescriptions containing glycyrrhizin, which is a strong inhibitor of 11 beta-hydroxysteroid dehydrogenase. We performed cross-over open trials in healthy subjects to clarify prednisolone pharmacokinetics on co-administration of these preparations. All subjects received a single oral dose of 10 mg prednisolone before oral treatment with one of the test preparations. After a 2-week wash-out interval, they received one of the test preparations for three days at daily doses of 7.5 or 9.0 g. On the third study day, 10mg prednisolone was administered orally in combination with the test preparation. Area under the curves (AUC) of prednisolone before and after the treatment decreased from 0.94 to 0.78 mg h L-1 (P < 0.05) in the Sho-saiko-To group, increased from 0.92 to 1.06 mg h L-1 (P < 0.01) in the Saiboku-To group, and did not change in the Sairei-To group. AUC ratios of prednisone and prednisolone, which reflect the 11 beta-hydroxysteroid dehydrogenase activity, increased in the Sho-saiko-To group (P < 0.01), decreased in the Saiboku-To group (P < 0.01), and did not change in the Sairei-To group after the treatments. Similar results were observed in ratios of endogenous cortisone to cortisol. Because of the equal glycyrrhizin content in all three preparations, it was unexpected that the 11 beta-hydroxysteroid dehydrogenase effect was different amongst the three groups. These observations suggest that some unknown metabolic enzyme modifiers, promoters or inhibitors, may be involved in these traditional treatments.

Induction of 73-kDa and 90-kDa heat shock protein expression in HL60 cells during differentiation

We investigated the expression of heat shock proteins HSP73 and HSP90 in human promyelocytic line HL60 during their differentiation induced by phorbor ester and all trans retinoic acid (ATRA). Polyclonal antibodies which had been raised against HSPs purified from bovine brains were used to detect human HSPs. Semiquantitation of HSPs was performed by immunoblotting. Induction of monocytoid and granulocytoid differentiation with phorbor ester and ATRA was accompanied by increased expression of HSP73 and HSP90 with distinct kinetics. Increased expression of both HSPs was confirmed by immunocytochemical studies. Our results suggest that HSP73 and HSP90 may be involved in differentiation of HL60 cells.

Interaction stabilizing tertiary structure of bacteriorhodopsin studied by denaturation experiments

The structural stability of bacteriorhodopsin was studied by denaturation experiments, using aliphatic alcohol as denaturants. The disappearance of a positive peak at 285 nm of the circular dichroism spectra, the change in the intrinsic fluorescence decay time, and the decrease of the regeneration activity bacteriorhodopsin indicated the denaturation of the tertiary structure of this protein at a methanol concentration of about 3 M. The circular dichroism band at 222 nm was unchanged by the denaturation. It was concluded that the alcohol-denatured state in water was similar to the molten globule state of soluble proteins, in which only the tertiary structure was destroyed. Solvent substitution from water to hexane did not cause denaturation of bacteriorhodopsin. However, further addition of alcohol destroyed the secondary as well as the tertiary structures. Comparing the alcohol effects of bacteriorhodopsin in water to that in hexane, the dominant interactions for the structure formation of this protein could be revealed: the hydrophobic interaction that arose from the structure of water is essential for the stability of membrane spanning helices, while the interaction which binds the helices is polar in nature.

Cloning of the cDNA encoding mast cell tryptase of Mongolian gerbil, Meriones unguiculatus, and its preferential expression in the intestinal mucosa

By using the combination of reverse-transcription PCR and rapid amplification of cDNA ends methods, a cDNA encoding mast cell tryptase was successfully cloned from the small intestine of Mongolian gerbil, Meriones unguiculatus, infected with Nippostrongylus brasiliensis. The cDNA was 1219 bp long including 810 bp of an open reading frame. Based on the deduced amino acid sequences of known mast cell tryptases of other species, the gerbil mast cell tryptase (gMCT) was highly similar to mouse mast cell protease (mMCP)-7, and seems to be translated as a prepro-enzyme with 25 amino acids of signal and activation peptides and 245 amino acids of mature enzyme. The gMCT mRNA was preferentially transcribed in the intestinal mucosa and to a far lesser extent in the connective tissue such as skin and tongue. Moreover, kinetic study after infection revealed that the amount of gMCT mRNA in the small intestine correlated well with the degree of intestinal mastocytosis. Throughout the course of infection, enzyme-histochemically detectable tryptase activity was limited to mucosal mast cells. Since mucosal mast cells of other rodents, including mice and rats, do not express tryptases, this is the first report of rodent mast cell tryptase expressed in the intestinal mucosa.

Plasma brain natriuretic peptide concentrations in healthy children from birth to adolescence: marked and rapid increase after birth

The aim of the present study is to establish the normal range and to determine the developmental changes of plasma brain natriuretic peptide (BNP) concentrations in children. We measured plasma BNP concentrations as well as atrial natriuretic peptide (ANP) concentrations in 58 healthy children from birth to adolescence and in the umbilical vein of 20 healthy neonates using highly sensitive immunoradiometric assays. The plasma BNP concentration was the highest at 0 days of age and descended through maturation to be almost constant and to be at the adult level at 3 months of age. The plasma BNP concentration at 0 days of age (56.7 +/- 49.6 fmol/ml; mean +/- SD) was 25 to 30 times higher than the adult level and 21 times higher than that in the umbilical vein (2.7 +/- 1.4 fmol/ml). The plasma ANP concentration at 0 days of age was not significantly different from that in the umbilical vein. The ratio of BNP to ANP was also the highest at 0 days of age (1.39 +/- 0.72) and decreased through maturation to be at the adult level at 3 months of age. Thus, the plasma BNP concentration in healthy subjects showed a marked, rapid and preferential increase immediately after birth, suggesting that BNP has a physiological role distinct from that of ANP in the perinatal circulatory changes from fetus to neonate.

Stenosis enhances role of platelets in growth of regional thrombus and intimal wall thickening in rat carotid arteries

The authors present the results of a study in which stenosis was induced, resulting in either thrombus or intimal wall thickening, in rat carotid arteries. At > or = 75% stenosis in mildly denuded arteries, an acute and occlusive thrombus formation was induced, but the thrombus was significantly reduced in thrombocytopenia. Thrombus formation near the site of stenosis decreased with decreasing degree of stenosis, whereas the percent formation in the distal region (percent total thrombus) increased. Numerous mural platelet microthrombi were noted at the distal region of the stenosed arteries. After chronic 50% stenosis of the carotid artery for 2 weeks, significant intimal thickening was observed, without any occlusive thrombus formation. The combination with mild denudation was critical in eliciting the effect of stenosis. The magnitude of intimal growth in the stenosed artery was marked by day 6 and plateaued thereafter, whereas it was slight in nonstenosed arteries. The 5-bromodeoxyuridine index of the cells of the medial layer at day 3 was significantly increased by the stenosis, and the effect was reversed in thrombocytopenia. Complete reendothelialization of the intimal surface was observed by 7 to 10 days after surgery in the stenosed arteries. These findings suggest that the introduction of stenosis in these arteries enhances the interaction of platelets with the damaged arterial walls under abnormal fluid shear and that this enhancement leads to acute and occlusive thrombus formation associated with more marked stenosis as well as to sustained increase of intimal wall thickness in less marked stenosis.

G protein beta gamma subunit activates Ras, Raf, and MAP kinase in HEK 293 cells

Using transient transfection of HEK 293 cells, we have studied the activation of Ras, c-Raf, and MAP kinase by G protein-coupled receptors, activated G protein alpha subunit (G alpha), and beta gamma subunits (G beta gamma). The expression of constitutively activated Gs alpha, Gi alpha, and G11 alpha did not have any effect on MAP kinase phosphorylation. In contrast, overexpression of G beta gamma could stimulate the phosphorylation of MAP kinase and enhance the MEK kinase activity of c-Raf. Coexpression of dominant negative Ras inhibited G beta gamma-induced phosphorylation of MAP kinase. Furthermore, the GTP-bound form of Ras was increased by overexpression of G beta gamma. These results strongly suggest that the G beta gamma may play an important role in signaling from G protein-coupled receptors to the MAP kinase pathway, and the activation of Ras and c-Raf may be involved in this signaling cascade in HEK 293 cells.