[Human hemoglobin structure and respiratory transport]

Hemoglobin carries oxygen from the lungs to the tissues and helps to transport carbon dioxide back to the lungs. It fulfills this dual role by clicking back and forth between two alternative structures, designated T for tense and R for relaxed, which are defined by the theory of allostery. Like all proteins, it is made up of small molecules called amino acids. A hemoglobin molecule is made up of four polypeptide chains, two alpha chains of 141 amino acid residues each and two beta chains of 146 amino acid residues each. In the complete molecule, four subunits are closely joined, as in a three-dimensional jigsaw puzzle, to form a tetramer. In the T structure, the subunits of the molecule are clamped by salt bridges and hydrogen bonds against the pressure of springs and their narrow pockets impede the entry of oxygen. In the R structure, all the clamps have sprung open and the heme pockets are open wide enough to admit oxygen easily. Uptake of oxygen by the T structure would strain the clamps until they all burst open in concert and allow the molecule to relax to the R structure. Loss of oxygen will narrow the heme pockets and allow the T structure to re-form.

Functional importance of amino-terminal domain of Shc for interaction with insulin and epidermal growth factor receptors in phosphorylation-independent manner

Shc has two distinct domains, amino-terminal and SH2 domain, which can interact with activated growth factor receptors. Shc interacts with insulin receptor via Shc-amino-terminal (N) domain, whereas Shc associates with epidermal growth factor (EGF) receptor through both Shc-N and -SH2 domains. In accordance with the different functional roles between insulin and EGF receptors, EGF stimulated tyrosine phosphorylation of Shc faster than insulin. To clarify the functional importance of three distinct Shc domains on insulin and EGF signaling, we microinjected glutathione S-transferase (GST) fusion proteins containing the amino terminus plus collagen homology domain (NCH), collagen homology domain (CH), and Src homology 2 domain (SH2) into Rat1 fibroblasts expressing insulin receptors (HIRc). Bromodeoxyuridine (BrdUrd) incorporation into newly synthesized DNA was subsequently studied to assess the importance of the three distinct domains of Shc. Microinjection of the NCH-GST fusion protein inhibited BrdUrd incorporation induced by both EGF and insulin, whereas microinjection of the SH2-GST fusion protein inhibited EGF, but not insulin stimulation of DNA synthesis. Neither EGF- nor insulin-induced BrdUrd incorporation was inhibited by the CH-GST fusion protein. Following EGF or insulin stimulation, Shc is phosphorylated on single Tyr-317 residue serving as a docking site for Grb2. Microinjection of Shc-N+CH GST fusion protein with Tyr-317 --> Phe replacement (Y317F) also inhibited insulin stimulation of DNA synthesis. Next, we stably overexpressed wild-type Shc or Y317F mutant Shc into HIRc cells. Insulin-induced tyrosine phosphorylation of IRS-1 was compared among the transfected cell lines, since IRS-1 and Shc could competitively interact with insulin receptor. Insulin-stimulated tyrosine phosphorylation of IRS-1 was decreased in both WT-Shc and Y317F-Shc cells compared with that in HIRc cells. Furthermore, overexpression of the Shc-SH2 domain or Shc-N+CH domain with Y317F mutation interfered with EGF-stimulated endogenous Shc phosphorylation. These results suggest that the amino terminus domain of Shc is functionally important in insulin- and EGF-induced cell cycle progression and that the phosphorylation of Shc Tyr-317 residue is independent of Shc interaction with these receptors.

Increased pancreatic metallothionein and glutathione levels: protecting against cerulein- and taurocholate-induced acute pancreatitis in rats

Recent findings have suggested that oxygen-derived free radicals play an important role in the development and progression of acute pancreatitis. Therefore, the present study was designed to investigate whether metallothionein, a free radical scavenger, can protect against acute pancreatitis. Rats were injected intraperitoneally with zinc, followed by either an infusion of cerulein at 10 micrograms/kg for 4 h or a retrograde injection with 100 microliters/100 g body weight of 5% sodium taurocholate into the pancreaticobiliary duct, in order to induce acute pancreatitis. Zn administration significantly increased the levels of both metallothionein and reduced glutathione in the pancreas; the metallothionein levels reached a peak of 83-fold of normal levels after 24 h. The indications of acute pancreatitis, as well as the mortality, were improved by Zn treatment before the onset of acute pancreatitis. Immunohistochemical studies showed that metallothionein accumulated in the acini of the pancreas in the Zn-treated groups, and with strong staining around the periphery of the vacuoles in the group treated with both Zn and cerulein. These findings suggested that Zn increased both metallothionein and glutathione levels in the pancreas and exerted a beneficial effect against ceruleinor taurocholate-induced acute pancreatitis in rats.

IL-8/NAP-1 is the major T-cell chemoattractant in synovial tissues of rheumatoid arthritis

T-cell infiltration into synovium is a crucial process for rheumatoid arthritis (RA). To investigate the mechanism of T-cell infiltration, we studied T-cell attracting activity in synovial tissue extracts of RA or osteoarthritis (OA) whose synovium lacks T-cell accumulation. RA extracts attracted twofold more T cells than OA extracts. By gel filtration column chromatography the activity of RA extracts was separated into two peaks; one was eluted at the 67-kDa region and the other was at the 12-kDa region, while the latter was absent in OA extracts. The activity eluted at the 12-kDa region was absorbed mostly by an antibody against IL-8/NAP-1, a potent T-cell chemotactic factor. IL-8/NAP-1 concentrations in RA extracts were much higher than those in OA extracts and correlated to T-cell attracting activity eluted at the 12-kDa region. The checkerboard analysis revealed that the 67-kDa activity was chemokinetic but not chemotactic. These results suggest that IL-8/NAP-1 is the major T-cell chemoattractant in RA-synovium.

Effect of glimepiride (HOE 490) on insulin receptors of skeletal muscles from genetically diabetic KK-Ay mouse

A new sulfonylurea, glimepiride (HOE 490), has been developed for the glycemic control in non-insulin-dependent diabetes mellitus. We examined the effect of glimepiride on glucose and insulin levels in KK-Ay mice, an animal model of non-insulin-dependent diabetes mellitus, which is characterized by hyperglycemia and hyperinsulinemia. Administration of glimepiride (0.5 mg/kg/day) for 8 weeks to KK-Ay mice resulted in decrease in glucose (297 +/- 36 to 250 +/- 51 mg/dl) and insulin (76 +/- 14 to 41 +/- 14 microU/ml) levels. To clarify the mechanism of the agent, we examined the effect of this new drug on insulin receptors in the skeletal muscles. There was no difference in insulin binding to the receptors from both glimepiride-treated and -untreated KK-Ay mice muscles. The insulin-stimulated autophosphorylation of insulin receptors from KK-Ay mice was decreased compared to that from normal mice (5 +/- 1 vs. 39 +/- 13% over basal). Glimepiride did not ameliorate impaired insulin-stimulated insulin receptor autophosphorylation. To determine the effect of glimepiride on post-insulin receptor signaling pathway, we measured 2-[3H]glycerol incorporation into diacylglycerol in the cultured rat fibroblast cell line overexpressing human insulin receptors. Glimepiride (100 microM) as well as insulin (10 nM) significantly stimulated diacylglycerol production. These results suggest that glimepiride has a potent extrapancreatic effect on glucose metabolism and may directly stimulate glucose transport activity through phospholipid signaling pathway, but not through insulin receptor kinase signaling pathway.

Effects of cholecystokinin and carbachol on membrane fluidity in pancreatic acini

The effects of pancreatic secretagogues on the membrane fluidity of pancreatic acini were investigated using 1-[4-(trimethylammonium)phenyl]-6-phenyl-1,3,5-hexatriene iodide as a probe. Two kinds of pancreatic secretagogues, one category of which induces acute pancreatitis (cholecystokinin and carbachol) and another which does not induce acute pancreatitis (bombesin, CCK-JMV-180, and secretin), as well as lecithin were used to investigate the effect of changes in membrane fluidity of acini. Our study revealed that the membrane fluidity of the pancreatic acini was unaffected by a physiological dose (10(-11) M) of cholecystokinin. However, stimulation with a supramaximal dose of cholecystokinin (10(-8) M) increased membrane fluidity markedly within 20 min. Membrane fluidity increased dose-dependently with increasing CCK stimulation. A supramaximal dose of cholecystokinin also induced bleb formation and increased LDH release. These phenomena were blocked by simultaneous incubation with CR1505 (Loxiglumide), a potent antagonist of peripheral cholecystokinin receptors. A supramaximal dose of carbachol (10(-3) M) also induced increases in the membrane fluidity. Pancreatic secretagogues that do not induce acute pancreatitis did not induce alterations in membrane fluidity. Lecithin increased both membrane fluidity and LDH release. These observations suggest that this increase in membrane fluidity of the pancreatic acini may be related to membrane alteration and to functional damage of the acini. These observations [correction of observation] can serve as a window to detect the development of acute pancreatitis at an early stage.

Effect of transforming growth factor-beta on fibroblasts in ossification of the posterior longitudinal ligament

We studied the immunohistochemical localization of TGF-beta in the ligament tissue of patients with ossification of the posterior longitudinal ligament (OPLL), and the effects of TGF-beta on cultured cells derived from the spinal ligament of patients with OPLL. ALP activity in the cultured cells was also examined. TGF-beta was present in the ossified matrix and in the chondrocytes in cartilaginous areas adjacent to OPLL. ALP activity was high in the cultured cells of OPLL patients. Exogenous TGF-beta inhibited proliferation in the OPLL cells but promoted proliferation in control cells. These results suggest that the spinal ligaments of OPLL patients have an osteogenetic predisposition and that TFG-beta may play a role in the ossification.

Pioglitazone attenuates the inhibitory effect of phorbol ester on epidermal growth factor receptor autophosphorylation and tyrosine kinase activity

A new anti-diabetic drug, pioglitazone, was tested as to whether it could ameliorate the decreased kinase activity of epidermal growth factor (EGF) receptor induced by phorbol ester (PMA) in A431 cells. The treatment of A431 cells with PMA decreased the tyrosine kinase activity of EGF receptors to 37% of normal in autophosphorylation and to 24% in tyrosine kinase activity toward Glu/Tyre synthetic polymers. Co-incubation of the cells with pioglitazone and PMA improved the receptor tyrosine kinase activity to 81% of control. Pioglitazone treatment alone did not change the kinase activity of EGF receptors. Pioglitazone did not decrease the PMA-activated protein kinase C activity and did not affect the protein tyrosine phosphatases activity in A431 cells. These results suggest that pioglitazone may act as a specific antagonist to the inhibitory effect by protein kinase C on the EGF receptor tyrosine kinase.

Screening of antipsychotic drugs by wide-bore capillary gas chromatography with nitrogen phosphorus detection--detection levels in plasma

The detection levels of 12 antipsychotic drugs as ascertained from drug screening were examined in order to use the screening results effectively for treatment of patients or medico-legal examinations in cases of poisoning. Wide-bore capillary gas chromatography with nitrogen phosphorus detection was used for the analysis. The detection limits of drugs in plasma using 3 extraction procedures, single-solvent, 3-step solvent and solid-phase extractions were 50-100 ng/ml, 10-200 ng/ml and 5-50 ng/ml, respectively. The detection limits were compared with blood levels previously reported in the literature. Only 4 drugs were detected at the therapeutic level, thioridazine, floropipamide, sultopride and oxypertine using the single-solvent extraction procedure. Using the 3-step solvent extraction procedure, chlorpromazine, levomepromazine and zotepine in addition to the above 4 drugs were detected. Using the solid-phase extraction procedure, 8 of 12 drugs were able to be detected at the therapeutic level, with the exception of perphenazine, haloperidol, bromperidol and nemonapride. These data were proved to be useful for a rapid forensic diagnosis.

A portable digital speech-rate converter for hearing impairment

A real-time hand-sized portable device that slows speech speed without changing the pitch is proposed for hearing impairment. By using this device, people can listen to fast speech at a comfortable speed. A combination of solid-state memory recording and real-time digital signal processing with a single chip processor enables this unique function. A simplified pitchsynchronous, time-scale-modification algorithm is proposed to minimize the complexity of the DSP operation. Unlike the traditional algorithm, this dynamic-processing algorithm reduces distortion even when the expansion rate is only just above 1. Seven out of 10 elderly hearing-impaired listeners showed improvement in a sentence recognition test when using speech-rate conversion with the largest expansion rate, although no improvement was observed in a word recognition test. Some subjects who showed large improvement had limited auditory temporal resolution, but the correlation was not significant. The results suggest that, unlike conventional hearing aids, this device can be used to overcome the deterioration of auditory ability by improving the transfer of information from short-term (echoic) memory into a more stable memory trace in the human auditory system.

Immunohistochemical study of metallothionein in pancreatic carcinomas

Metallothioneins are a family of intracellular metalloproteins that have been thought to be involved in anticancer drug resistance. However, the role of metallothioneins in pancreatic cancer has not been investigated in detail. The immunohistochemical localization of metallothionein was examined in normal human adult pancreas tissue and in 75 pancreatic duct cell carcinomas, using monoclonal anti-metallothionein antibody. Furthermore, in vitro studies on the sensitivity of pancreatic cancer to cisplatin were performed in 10 cases of pancreatic carcinoma. Metallothionein staining was weakly positive in the acinar and islet cells and intralobular ducts but was negative in the large pancreatic ducts. In pancreatic carcinomas, metallothionein staining was diffusely positive in 6 (8%), focally positive in 25 (33%) and negative in 44 (59%) of the 75 pancreatic carcinomas. The expression of metallothioneins in pancreatic tumors was related to metastasis, poor prognosis and poor histological grading (poorer glandular differentiation and nuclear anaplasia). The in vitro study of tumor sensitivity to cisplatin showed no significant correlation between metallothionein expression and resistance to cisplatin. Metallothionein-positive pancreatic carcinoma will be potentially highly malignant or acquire an enhanced ability to produce metallothioneins as the malignant potential increases. The expression of metallothionein could be a prognostic indicator in pancreatic carcinomas.

Immunohistochemical localization of P-glycoprotein and expression of the multidrug resistance-1 gene in human pancreatic cancer: relevance to indicator of better prognosis

We investigated immunohistochemical localization of P-glycoprotein (P-gp) on paraffin-embedded sections from 103 cases of previously untreated pancreatic tumors and also analyzed multidrug resistance-1 (MDR1) gene expression by polymerase chain reaction after reverse transcription in 35 cases. High positive staining for P-gp was observed in 72.8% of pancreatic tumors and in 73.2% of ductal adenocarcinoma. In ductal adenocarcinoma, immunoreactivity of P-gp was inversely correlated with biological aggressiveness of tumors determined by histologic grading (P<0.01), tumor size (P < 0.01), retroperitoneal invasion (P < 0.01) and portal invasion (P < 0.05). Expression of the MDR1 gene was detected in all the pancreatic tumors examined and was significantly higher than that in normal pancreas (P < 0.05). The levels of MDR1 mRNA showed a moderate correlation with those of P-gp (r=0.62, P<0.0001). Higher expression levels of MDR1/P-gp significantly correlated with better prognosis of patients with ductal carcinoma (P < 0.05). Among patients with ductal carcinoma, the high staining group for P-gp revealed a 3.5-fold better prognosis compared with the low staining group (HR=3.47, 95% CI=1.62, 7.45; P=0.0016). In conclusion, MDR1 gene/P-gp expression in pancreatic cancer without chemotherapy inversely correlates with biological aggressiveness and is an independent indicator of favorable prognosis.

Induction of vascular permeability enhancement by human tryptase: dependence on activation of prekallikrein and direct release of bradykinin from kininogens

Tryptase is a trypsin-type serine protease that is released from mast cells. Bradykinin (BK) is released directly from kininogens or through activation of either Hageman factor or subsequent plasma prekallikrein. Its nasal administration or inhalation induces allergy-like symptoms. Although elevated levels of tryptase and BK in allergic fluids have been detected, the role of this proteinase and the mechanism of BK production at allergic reaction sites are still unknown. To investigate the pathologic functions of tryptase, the enzyme, purified from human lung, was incubated with normal human plasma, deficient plasmas, kininogens, or prekallikrein. High molecular weight kininogen was then added, and the mixtures were examined for vascular permeability enhancement (VPE) activity, a representative function of bradykinin, using guinea pig skin. Tryptase-treated plasma induced VPE in a dose-dependent manner; activity was lost in the absence of a kininase inhibitor but not an antihistamine drug. Tryptase produced VPE activity from normal or Hageman factor-deficient plasma, but only 30% of this activity was produced from prekallikrein-deficient plasma. Significantly, no activity was obtained from kininogen-deficient plasma. Deficient plasma that were reconstituted with each missing factor resulted in VPE-inducing capacity by tryptase, equivalent to that found with normal plasma. Incubation of tryptase with high or low molecular weight kininogen induced VPE activity in a dose- and incubation time-dependent manner. Prekallikrein incubated with tryptase also generated a soybean trypsin inhibitor-sensitive VPE-inducing activity from high molecular weight kininogen. The loss of tryptase VPE-producing activity as a function of incubation time was found to be a result of spontaneous inactivation of the enzyme and not of the degradation of high molecular weight kininogen by the enzyme. We conclude that tryptase induces VPE by releasing BK, primarily through prekallikrein activation, but also through direct release from kininogens. This indicates that this mast cell-derived proteinase contributes to kinin production in allergic diseases.

Increased plasma adrenomedullin levels in chronic congestive heart failure

Adrenomedullin is a potent vasodilator peptide and occurs in circulating blood of human beings and experimental animals. Because it is produced in intact aorta of rats and in cultured vascular endothelial cells, adrenomedullin seems to participate in regulation of local vascular tone. To determine the pathophysiological roles of adrenomedullin, we investigated its plasma concentrations in 49 patients with heart failure. Plasma adrenomedullin levels increased significantly with advancing severity of the disease (New York Heart Association functional class I, 4.1 +/- 1.0; II, 5.6 +/- 1.6; III, 6.4 +/- 0.8; IV, 13.2 +/- 6.8 (fmol/l). Plasma adrenomedullin was correlated with pulmonary artery pressure (r = 0.44, p = 0.0114) and pulmonary capillary wedge pressure (r = 0.53, p = 0.0002). These findings indicate that adrenomedullin may play some important role in the pathophysiologic makeup of heart failure by its vasodilating effects against the concomitant exaggeration of humor pressor agents such as catecholamine and the renin-angiotensin system. Hemodynamic changes in pulmonary circulation may have some influence on the increased synthesis and secretion of plasma adrenomedullin in chronic congestive heart failure.

Identification of a 79-kDa heparin-binding fibroblast growth factor (FGF) receptor in rat hepatocytes and its correlation with the different growth responses to FGF-1 between hepatocyte subpopulations

We reported previously that the potency of heparin-binding fibroblast growth factor-1 (FGF-1) as a mitogen for rat hepatocytes in primary culture is as high as that of epidermal growth factor (EGF) and hepatocyte growth factor. To gain insight into the pathophysiological significance of FGF-1 in hepatocyte growth, we analyzed the cooperative mitogenicity of FGF-1 and EGF. Results from a nuclear labeling assay using [3H]thymidine suggest that most hepatocytes in primary culture consist of two cell populations that differ in response to FGF-1; one is an FGF-1-responsive cell population, and the other is an EGF-responsive (but not FGF-1-responsive) cell population. On the other hand, autoradiographic analysis of 125I-FGF-1 binding demonstrated that high affinity FGF receptors were homogeneously distributed on the surface of all hepatocytes. Cross-linking 125I-FGF-1 to the nonstimulated hepatocyte surface indicated that the high affinity FGF receptors comprise two FGF receptors that differ in molecular mass (128 and 79 kDa). Furthermore, the 79-kDa receptor was preferentially down-regulated when the hepatocytes were stimulated with EGF or hepatocyte growth factor. These data suggest that the abundant expression of the 79-kDa FGF receptor on some populations of hepatocytes is involved in their lack of response to FGF-1. The 128- and 79-kDa FGF receptors were assigned as FGFR2 using an antibody specific to the ectodomain of FGFR2, whereas the 79-kDa receptor was not reactive to the antibody against the carboxyl terminus of FGFR2. This 79-kDa FGF receptor was not tyrosine-phosphorylated in response to FGF-1 stimulation, while the 128-kDa FGF receptor was recognized by anti-phosphotyrosine antibody under the same conditions. Also, the heterodimer of 79- and 128-kDa FGF receptors was less tyrosine-phosphorylated than the homodimer of 128-kDa FGF receptors. These data suggest that the 79-kDa FGF receptor inhibits the function of the 128-kDa FGF receptor through their heterodimerization. Thus, we surmise that the difference in response to FGF-1 between the cell populations of normal rat hepatocytes was caused by the different levels of the 79-kDa FGF receptor in each cell population.

Increased plasma adrenomedullin in acute myocardial infarction

Adrenomedullin has a potent vasodilating effect comparable to that of calcitonin gene-related peptide. To investigate the pathophysiologic role of endogenous adrenomedullin, we determined sequentially the plasma adrenomedullin level in 15 consecutive patients with acute myocardial infarction (AMI). Plasma adrenomedullin was higher immediately after the onset of AMI and decreased gradually; plasma levels during the 3-week period after the AMI were higher than plasma levels in 15 healthy control subjects (p < 0.001), with higher levels in patients with congestive heart failure than in patients without congestive heart failure throughout the period of the study (p < 0.05). Plasma adrenomedullin was positively correlated with pulmonary capillary wedge pressure, pulmonary arterial pressure, right atrial pressure, and heart rate in the early stage of AMI. These findings suggest that the elevation of plasma adrenomedullin is related to the retention of body fluid volume, the enhancement of sympathetic activity, and/or the elevation of pressure in pulmonary vascular beds. Adrenomedullin may act against excessive vasoconstrictors increased in AMI.

Brain death diagnosed by forensic analysis of drug distribution in human tissues-II--Distribution of caffeine in brain dead patients

Caffeine concentrations in human tissues of 6 brain death cases as well as 5 non-brain death cases were examined in order to assess the possibility of diagnosing brain death based on an analysis of this compound. Concentrations of caffeine in human tissues were determined using gas chromatography/mass spectrometry. The tissue-to-blood concentration ratios were used to evaluate the distribution pattern in each case. In non-brain death cases, the ratios in all examined tissues were similar, and the values were close to 1 in all tissues except adipose, of which the value was near 0.3. In brain death cases, the ratios in all tissues except brain and adipose were similar to those in non-brain death cases. The ratios in the brain were higher than those of non-brain death cases, in 5 brain death cases, and lower in 1 brain death case to whom blood transfusion was done in a hospital. The ratios in the adipose were slightly higher in brain death cases than those in non-brain death cases. The discorded distribution of caffeine in brain death cases was presumably related to cessation of cerebral blood circulation at the time of brain death. Therefore, comparing caffeine concentrations in the brain with those in the other tissues can be useful for a forensic diagnosis of brain death.

A case of drowning linked to ingested sulfides--a report with animal experiments

An adult male was found dead beneath a pool of sewage in the pump room of a fish market. Autopsy revealed the cause of death to be suffocation after aspirating sewage into the respiratory tract. Since hydrogen sulfide gas was detected in the atmosphere at the scene of the accident, gas poisoning was suspected and toxicological analysis of sulfides in body tissues was performed. The concentrations of sulfides in the blood, lung and kidney were 0.95 mumol@ml, 0.22 and 0.38 mumol/g, respectively. These values were remarkably higher than those in previously reported cases involving exposure to hydrogen sulfide gas. Therefore, oral intake of sulfides was assumed and the distribution of sulfides in tissues following oral administration of sodium sulfide solution was examined by means of animal experiments using rats. The concentration of sulfides in the blood from rats following oral intake was much higher than that seen following gas exposure. Based on these results, we concluded that the victim had been exposed to hydrogen sulfide gas and had then collapse into a pool of sewage containing sulfides. The sulfides which were distributed throughout the body tissues had mainly issued from the alimentary tract prior to death by drowning.

Sensitive determination of bromazepam in human tissues using capillary gas chromatography-mass spectrometry

A reliable and sensitive gas chromatographic-mass spectrometric method was devised to determine the levels of bromazepam in human tissues. Bromazepam was extracted from body tissues using a three-step solvent extraction procedure. N-Desmethyldiazepam served as the internal standard. Selected ion monitoring with m/z 317 for bromazepam and m/z 270 for internal standard was used for quantitation. Calibration curves in all body tissues were linear over the concentration range from 50-500 ng/g. The lower detection limit in body tissues was 2-5 ng/g and the absolute recovery in body tissues was 27.8-68.0%. This method was used to determine the levels of bromazepam in tissues of an autopsied individual who had been prescribed psychotropic drugs and who was found dead in a car.

A novel chimeric fibroblast growth factor for liver parenchymal cells

Although fibroblast growth factor 1 (FGF-1) (formerly known as acidic FGF) but not FGF-2 (or basic FGF), has been suggested to play a pathophysiological role in liver regeneration, its clinical application has been restricted by its limited mitogenecity and heparin dependence. We report here that a chimeric human FGF protein, FGF-C(1211), is a heparin-independent potent mitogen for liver parenchymal cells both in vitro and in vivo. In the presence of serum and physiological concentration of insulin, FGF-C(1211) by itself induces as much as 55% of hepatocytes in culture to proliferate and up to 88% when used in combination with hepatocyte growth factor or epidermal growth factor. Furthermore, hepatocytes nuclear labeling in vivo with bromodeoxyuridine was markedly enhanced when FGF-C(1211) was injected intravenously into carbon tetrachloride-administered mice. Because FGF-C(1211) is heparin independent and nonantigenic, it has potential for clinical and preclinical applications.

Induction of apoptosis in murine clonal osteoblasts expressed by human T-cell leukemia virus type I tax by NF-kappa B and TNF-alpha

We investigated the effects of various cytokines in the presence of human T-cell leukemia virus type I (HTLV-I) tax protein in murine clonal osteoblasts, MC3T3-E1 cells. Skeletal remodeling by osteoclasts and osteoblasts is coordinated by cytokines, which are activated by HTLV-I tax protein via nuclear factor-kappa B (NF-kappa B). MC3T3-E1 cells were cocultured with an irradiated HTLV-I-producing lymphocyte cell line, MT-2. After coculture, the tumor necrosis factor-alpha (TNF-alpha) level in the medium was markedly elevated during the 7 days of culture, and MC3T3-E1 cells underwent apoptotic cell death. Marked apoptosis was also observed in MC3T3-E1 cells treated with MT-2 culture medium and in HTLV-I tax-expressing MC3T3-E1 clones, which both expressed high levels of TNF-alpha. This apoptosis was prevented by treatment with neutralizing anti-TNF-alpha antibody (alpha TNF). HTLV-I tax protein and TNF-alpha induced activation of NF-kappa B in apoptotic MC3T3-E1 cells. Decreased NF-kappa B activation was observed in HTLV-I tax-expressing MC3T3-E1 cells treated with alpha TNF. Our results suggest that HTLV-I tax activated NF-kappa B and subsequently TNF-alpha, leading to apoptosis of osteoblasts.

The clinical utility of visual evaluation of scintigraphic perfusion patterns for Alzheimer's disease using I-123 IMP SPECT

The authors examined the role of SPECT perfusion pattern in the diagnosis of Alzheimer's disease (AD) using I-123 IMP. They studied 93 patients who had memory and cognitive disorders, including 42 patients with a diagnosis of probable AD, classifying SPECT images into determined perfusion patterns. The probability of AD was 54% with bilateral temporal and/or parietal defects, 69% with bilateral temporoparietal defects with additional defects, 17% with no defects, and 11% with frontal defects only. The sensitivity of bilateral temporoparietal perfusion defects for AD was 95.2%, whereas the specificity was 56.9%. In the absence of bilateral temporal and/or parietal defects on visual evaluation of SPECT, the diagnosis of AD was unlikely, although it is not pathognomonic for AD, because this sign would be seen in various neuropsychiatric diseases causing memory and cognitive impairments. Visual evaluation of SPECT is of value in the diagnosis of AD among patients with dementia.

Hsp70 family molecular chaperones and mutant insulin receptor: differential binding specificities of BiP and Hsp70/Hsc70 determines accumulation or degradation of insulin receptor

We have examined the binding specificities of Hsp70 family molecular chaperones, BiP and Hsp70/Hsc70, to wild-type or mutant insulin receptors. BiP bound to proreceptor of wild-type insulin receptor, but not to mature receptor. A mutant insulin receptor, which lacked 47 amino acid residues (delta Ex13 IR) corresponding to exon 13 of insulin receptor gene, accumulated in the endoplasmic reticulum as uncleaved proreceptor with immature oligosaccharide chains. This deletion mutant bound to BiP more tightly than wild type. Introduction of two types of mutations, Asp1179 or Leu1193, into delta Ex13 IR led to accelerated degradation, and these double mutants bound weakly to BiP. In contrast, Ser735 insulin receptor was normally transported to the plasma membrane and normally bound to BiP. Furthermore, Asp1179, Leu1193 insulin receptors and delta Ex13 IR combination mutant with either Asp1179 or Leu1193 bound more tightly to Hsp70/Hsc70 compared with wild-type, Ser735, and delta Ex13 IR. These results suggest that the binding specificity of mutant insulin receptors to two molecular chaperones, i.e., BiP and Hsp70/Hsc70, plays an important role for their posttranslational processing that may lead to the accumulation in the endoplasmic reticulum or the degradation of insulin receptors.

Signal transduction pathway of interleukin-4 and interleukin-13 in human B cells derived from X-linked severe combined immunodeficiency patients

Interleukin-4 (IL-4) and IL-13 are functionally similar cytokines. The functional IL-4 receptor (IL-4R) consists of the IL-4R alpha chain (IL-4R alpha) and the IL-2R gamma chain (gamma c), which is shared by the IL-2, IL-7, IL-9, and IL-15 receptors. The functional IL-13R is thought to involve the IL-4R alpha but not gamma c. In this study, we have analyzed activation of members of the Janus tyrosine kinase (Jak) family and signal transducers and activators of transcription (STAT) 6 induced by IL-4 and IL-13 in Epstein-Barr virus-transformed B cells derived from two patients of X-linked severe combined immunodeficiency, who have mutations of the gamma c gene in the extracellular and intracellular domains. In these B cells, IL-4 failed to induce tyrosine phosphorylation of Jak3 and activation of STAT6, or activation of these molecules was significantly decreased compared with Epstein-Barr virus-transformed normal B cells. In contrast, IL-13 activated STAT6 in these cells as well as normal B cells. However, Jak3 was not activated by IL-13, even in normal B cells. These results clearly indicated that gamma c is essential for activation of Jak3 and STAT6 in the signal transduction pathway of IL-4 in human B cells and that IL-13 does not utilize gamma c but activates STAT6 through an alternative pathway, which is not impaired in B cells of X-linked severe combined immunodeficiency patients.