Altered Gq/G11 guanine nucleotide regulatory protein expression in a rat model of hepatocellular carcinoma: role in mitogenesis

Guanine nucleotide regulatory proteins (G-proteins) represent an important transmembrane pathway whereby extra-cellular signals are transduced to intracellular signaling pathways. The mitogen-activated protein kinase (MAPK) cascade has been identified as a key factor in transducing numerous mitogenic stimuli. MAPK activity is regulated via numerous receptor types, including those linked to Gq/G11-proteins, which regulate phospholipase-C activity. We hypothesized that alterations in a Gq/G11-PLC pathway may contribute to the enhanced cellular mitogenesis characteristic of hepatocellular carcinoma (HCC), possibly via a MAPK-dependent pathway. By using an in vivo model of HCC we investigated changes in Gq/G11-protein expression in tumorigenic tissue versus adjacent, non-neoplastic liver. In addition we addressed the role of Gq/G11-proteins in the regulation of MAPK-linked mitogenesis by using rat hepatic tumorigenic cells (H4IIE) and isolated hepatocytes in culture. Western blot analysis showed significant increases in Gqalpha and G11alpha expression in tumorigenic liver versus normal liver specimens, an effect that was augmented in cultured H4IIE cells versus isolated cultured hepatocytes. Furthermore, phosphoinositol specific phospholipase-C (PLC) activity was significantly increased in HCC versus normal liver. A specific PLC inhibitor (Et-18-OCH3) caused a dose-dependent decrease in serum stimulated DNA synthesis in both cultured H4IIE cells and isolated rat hepatocytes, the H4IIE cell line showing greater sensitivity to Et-18-OCH3. In addition, serum-stimulated MAPK activity was significantly enhanced in H4IIE versus cultured hepatocytes. Moreover, treatment with Et-18-OCH3 significantly attenuated serum stimulated MAPK activity in both cultured hepatocytes and H4IIE cells. Furthermore, U73122 (Gqalpha-PLC specific uncoupler) and GP2A (Gqalpha specific inhibitor) mirrored the effects of those observed for Et-18-OCH3 whereas PD98059 (specific MEK inhibitor) completely abolished serum-stimulated DNA synthesis in tumorigenic H4IIE cells. We conclude that HCC is associated with enhanced Gq/G11-PLC expression/activity as compared with normal liver. Furthermore, a PLC-linked MAPK cascade plays a significant role in the progression of the enhanced mitogenesis characteristic of HCC.     

Sensation recovery on innervated radial forearm flap for hemiglossectomy reconstruction by using different recipient nerves

The objectives of this study were (1) to determine the extent of sensory recovery on hemitongues reconstructed with innervated radial forearm flaps and (2) to assess the influence of various clinical and surgical factors over the return of sensation, including the use of different recipient nerves for neurorrhaphy. Twenty-eight patients with tongue cancer who underwent hemiglossectomy and primary reconstruction with innervated radial forearm flaps over a 3-year period were studied. Mean postoperative follow-up was 18.2 months (range 6 to 32 months). Sensory recovery was assessed in a blind manner by two examiners that used (1) static two-point discrimination, (2) light touch sensation, (3) pain perception, and (4) hot and cold temperature perception. Different surfaces were assessed with each method on the reconstructed hemitongue and on the intact contralateral hemitongue (used as control). The following factors and their relationship with flap sensory recovery were analyzed: age, smoking history, size of the reconstructed defect, administration of postoperative radiation therapy, recipient nerve, and neurorrhaphy technique. Comparative statistical analysis (p < 0.05) between both hemitongues was performed using paired t test followed by Bonferroni correction for static two-point discrimination and light touch sensation. Fisher exact test analysis was used for pinprick and hot and cold temperature perception. The control side was ignored in analyzing the effects of the risk factors. The tip, dorsal aspect, ventral surface, and floor of mouth on the reconstructed hemitongue had comparable static two-point discrimination when compared with the intact hemitongue. Light touch sensation was also similar in the tip and dorsal aspect of both hemitongues; however, a statistically significant difference (p < 0.05) was observed on the ventral surface and floor of mouth of the reconstructed hemitongues. Likewise, pain perception was significantly decreased in the floor of the mouth, compared with other surfaces. No clearly dependent association was established between return of flap sensation and age, tobacco use, and size of the reconstructed defect. Light touch sensation, pain, and temperature perception were significantly decreased when the patients had received postoperative radiation therapy. In addition, all four sensory tests were significantly diminished (p < 0.05) when the recipient nerve used for neurorrhaphy was a nerve other than the lingual or the inferior alveolar nerve, and also when an end-to-side nerve repair was used. Sensation recovery of the innervated radial forearm flap after hemitongue reconstruction approaches normal compared with the contralateral intact hemitongue. Lower return of sensation may be anticipated in patients who receive postoperative radiotherapy. Good recovery of sensation is predictable when either the lingual or inferior alveolar nerve is used for neurorrhaphy, in contrast to using other recipient nerves.     

Transurethral balloon dilation of the external urinary sphincter: effectiveness in spinal cord-injured men with detrusor-external urethral sphincter dyssynergia

The authors investigated balloon dilation as a minimally invasive alternative to transurethral external sphincterotomy for the treatment of detrusor-external urethral sphincter dyssynergia (DESD). Seventeen spinal cord-injured men with voiding pressures greater than 60 cm H2O underwent balloon dilation of the external sphincter to 90 F at 4 atm of pressure for 10 minutes. The mean voiding pressures before and 12 months after dilation were 83 cm H2O +/- 35 and 37 cm H2O +/- 15, respectively (P = .008). There was a significant decrease in residual urine volume, from 163 mL +/- 162 to 68 mL +/- 59 (P = .05), whereas bladder capacity remained relatively unchanged at 253 mL +/- 181 and 230 mL +/- 97 (P = .30). Complications included one case of postoperative bleeding necessitating transfusion, two treatment failures, and one bulbous urethral stricture. Fourteen of the 17 patients (82%) now void without the aid of an indwelling catheter or alternative therapy. Balloon dilation has no detrimental effect on erectile function and may improve fertility.     

Myelin/oligodendrocyte glycoprotein is a member of a subset of the immunoglobulin superfamily encoded within the major histocompatibility complex

Myelin/oligodendrocyte glycoprotein (MOG) is found on the surface of myelinating oligodendrocytes and external lamellae of myelin sheaths in the central nervous system, and it is a target antigen in experimental autoimmune encephalomyelitis and multiple sclerosis. We have isolated bovine, mouse, and rat MOG cDNA clones and shown that the developmental pattern of MOG expression in the rat central nervous system coincides with the late stages of myelination. The amino-terminal, extracellular domain of MOG has characteristics of an immunoglobulin variable domain and is 46% and 41% identical with the amino terminus of bovine butyrophilin (expressed in the lactating mammary gland) and B-G antigens of the chicken major histocompatibility complex (MHC), respectively; these proteins thus form a subset of the immunoglobulin superfamily. The homology between MOG and B-G extends beyond their structure and genetic mapping to their ability to induce strong antibody responses and has implications for the role of MOG in pathological, autoimmune conditions. We colocalized the MOG and BT genes to the human MHC on chromosome 6p21.3-p22. The mouse MOG gene was mapped to the homologous band C of chromosome 17, within the M region of the mouse MHC.     

Characterization of the testis and epididymis in mouse models of human Tay Sachs and Sandhoff diseases and partial determination of accumulated gangliosides

Beta-hexosaminidase (Hex) is an essential lysosomal enzyme whose activity is higher in the epididymis than in other tissues. The enzyme is also present in sperm and has been postulated to be required for fertilization. To better understand the role of Hex in reproduction, we have examined the testes and epididymides of mouse models of human Tay Sachs and Sandhoff diseases, produced by targeted disruption of the Hexa (alpha-subunit) or Hexb (beta-subunit) genes, respectively, encoding the enzymes Hex A (structure, alphabeta) and Hex B (betabeta). Testis weight, morphology, and sperm counts were unaffected in Hex-deficient mice. In the epididymis of the Hex A-deficient Hexa-/- mice, there was a large increase in the size and number of lysosomes in the initial segment/intermediate zone. In Hexb-/- mice (Hex A and B-deficient), the epididymal defects were much more extensive and the cytoplasm of all cell types throughout the efferent ducts and epididymis was filled with pale, uncondensed, enlarged lysosomes. In contrast to the brain where GM2 ganglioside accumulates, both mutant mice accumulated two non-GM2 gangliosides in the epididymis. The major accumulated species was characterized by electrospray ionization tandem mass spectrometry. The Hexa-/- male mice were fertile; however, litter sizes were reduced. The Hexb-/- males were able to sire normal sized litters up to nine weeks of age and remained healthy until 16-20 weeks of age. The extensive abnormalities in the Hexb-/- mice, in contrast to region-specific effects in the Hexa-/-mice, indicate an important and novel role for the Hex B isozyme in the epididymis and a region-specific role for Hex A in the initial segment/intermediate zone. In contrast to other reports, our results indicate that Hex is not essential for fertilization in young adult male mice. To explain the extensive epididymal abnormalities in the Hexb-/- mice, we propose that substrates for Hex, such as testis-derived glycolipids, cannot be catabolized and accumulate in lysosomes, leading to epididymal dysfunction and abnormalities in the epididymal luminal environment that supports sperm maturation.     

Clinical management of malignant hyperpyrexia

Experience with eight cases of malignant hyperpyrexia are presented. The different types are described and illustrated by clinical cases. Early recognition of this condition is the cornerstone in the successful management of the complication. Early diagnosis and methods of treatment are described.     

Uptake of ATP by liver and kidney in vitro

Rat liver and kidney slices were incubated at 37 degrees C for 1 h in 1.0 ml of Krebs-HCO3 buffer containing 10mM glucose and one of the following: 5 mM [8-14C]ATP, 5 mM [8-14C]ADP, 5 mM [8-14C]AMP, or 5 mM [8-14C]ation medium and tissue extract were subjected to electrophoretic separation and the radioactivity present in ATP, ADP, AMP, IMP, inosine, adenosine, and hypoxanthine was counted. Extensive degradation of the added nucleotide was observed in the presence of both tissues. The concentrations of 14C-labeled ATP and ADP found in the liver and kidney indicated that these compounds were present within the cells. Evidence is presented which suggests that ATP, and to a lesser extent ADP, entered the liver and kidney as such and were not synthesized within the cell from 14C-labeled adenosine.