Evidence for survival and metabolic activity of encapsulated xenogeneic hepatocytes transplanted without immunosuppression in Gunn rats

BACKGROUND

Hepatocyte transplantation could be an alternative to whole organ transplantation to correct enzymatic disorders. To this end, it would be of major importance to use xenogeneic cells without immunosuppression. The aim of this study was to investigate the survival and metabolic activity of encapsulated xenogeneic hepatocytes in the absence of immunosuppression. For this purpose, we used Gunn rats genetically incapable of bilirubin conjugation.

METHODS

Xenogeneic (from guinea pigs) and allogeneic (from Lewis rats) hepatocytes (2x10(7)) were isolated, macroencapsulated in hydrogel hollow fibers made with an acrylonitrile-sodium methallyl-sulfonate copolymer, and transplanted into the peritoneum of Gunn rats without any immunosuppression. Plasma bilirubin levels were evaluated weekly. Bilirubin conjugates in bile and cell morphology were studied after 5 and 12 weeks, respectively.

RESULTS

In Gunn rats transplanted with xenogeneic hepatocytes, a significant decrease in the serum bilirubin level was observed between 3 and 9 weeks after transplantation when compared with controls transplanted with empty hollow fibers: it fell to 62% of the initial level at weeks 5-7 (P < 0.01). A comparable result was observed in Gunn rats transplanted with encapsulated allogeneic cells. Bilirubin conjugates were observed in bile samples of rats transplanted with encapsulated hepatocytes. After explantation, hollow fibers appeared intact with minimal fibrosis. Cell viability and hepatocyte morphology were preserved.

CONCLUSIONS

These results indicate that macroencapsulated xenogeneic hepatocytes can survive and remain functional for more than 2 months when transplanted in vivo in the absence of any immunosuppression.

Androgen regulation of lung lipids in the male rat

The aim of this study was to determine whether or not testosterone regulates the lipid concentration in rat lung tissue. Rats were either sham-operated controls, castrated, or castrated and injected with testosterone. Twenty-one days after castration, we observed in relation to the control: (i) Total lipids, phospholipids, and total cholesterol increased, while triglycerides decreased in whole lung. (ii) Phospholipid concentration increased in microsomes, lamellar bodies, and alveolar macrophages, but it decreased in extracellular surfactant. (iii) On a percentage basis, the concentration of phosphatidylcholine increased in microsomes, lamellar bodies, and alveolar macrophages, and it decreased in extracellular surfactant. (iv) Protein concentration decreased in extracellular surfactant and increased in microsomes, lamellar bodies, and alveolar macrophages. (v) The incorporation of [14C]glycerol into phospholipids of lung slices increased. (vi) The activity of CTP:phosphocholine cytidylytransferase bound to the microsomal fraction increased without any change in the activity of the soluble form of the enzyme in the lung. The results obtained when testosterone was administered to castrated rats were similar to those obtained in the control in all cases. These results suggest that the lipid concentration in the lung is regulated at least partly directly or indirectly by androgens.

Microalbuminuria is associated with limited joint mobility in type I diabetes mellitus

OBJECTIVE

To determine whether limited joint mobility (LJM) is associated with microalbuminuria in type I diabetes mellitus.

METHODS

Joint mobility was measured in a control group of 63 healthy subjects and in 63 type I diabetic patients, older than 18 years (mean 31.7 years, range 18-57), recruited from the outpatient clinic of the Endocrine Unit. Patients with established diabetic nephropathy (proteinuria or increased creatinine) were excluded. Joint mobility was assessed qualitatively with the prayer manoeuvre and quantitatively by measuring the angles of maximal flexion and extension of the fifth and third metacarpophalangeal (MCP) joints and wrist. Diabetic retinopathy was assessed by direct ophthalmoscopy. Urinary albumin excretion (UAE) was determined in at least two 24 hour urine samples.

RESULTS

Joint mobility was limited in diabetic patients compared with control subjects. Diabetic patients with LJM had longer duration of diabetes (12.1 (SD 6.4) years compared with 6.9 (5.7) years; p < 0.001). Joint mobility was limited in patients with retinopathy: prayer manoeuvre was positive in 96.4% of patients with retinopathy, but in only 40.0% of patients with no retinopathy (p < 0.001); mobility of MCP joints and wrist was limited in diabetic patients with retinopathy even when the longer duration of their diabetes was taken into consideration. Microalbuminuria, present in 11 patients (17.5%), was associated with LJM: prayer manoeuvre was positive in 90.9% of patients with microalbuminuria, but in only 57.4% of patients with normal UAE (p < 0.05). Maximal flexion of MCP joints was reduced in patients with microalbuminuria. Microalbuminuria, but not LJM, was associated with risk factors of cardiovascular disease.

CONCLUSION

LJM is associated with microalbuminuria and retinopathy in type I diabetes. The association is independent of age and duration of diabetes.

Inactivation of p42 MAP kinase by protein phosphatase 2A and a protein tyrosine phosphatase, but not CL100, in various cell lines

BACKGROUND

Mitogen-activated protein (MAP) kinase is central to a signal transduction pathway that triggers cell proliferation or differentiation. Activation of the p42mapk isoform requires its phosphorylation at two residues, Thr 183 and Tyr 185, and this phosphorylation is catalysed by MAP kinase kinase (MAPKK). Relatively little is known, however, about the enzymes that dephosphorylate these residues, thereby inactivating the pathway. Recently, the CL100 phosphatase has been shown to inactivate p42mapk in vitro by dephosphorylating Thr 183 and Tyr 185 at similar rates. CL100, the product of an immediate early gene, is synthesized within one hour of stimulating cells with growth factors or exposure to oxidative stress or heat shock. Incubation of NIH 3T3 fibroblasts with cycloheximide prevents both synthesis of CL100 and inactivation of p42mapk after stimulation with serum.

RESULTS

Depleting cells of CL100 and preventing its induction using cycloheximide stopped the inactivation of p42mapk in Swiss 3T3 fibroblasts following stimulation with epidermal growth factor (EGF), but had no effect on the rapid inactivation of p42mapk in response to EGF in adipose (3T3-L1) or chromaffin (PC12) cells or in response to platelet-derived growth factor (PDGF) in endothelial (PAE) cells. Moreover, maximal induction of CL100 mRNA and a CL100-like activity did not trigger inactivation of p42mapk, which was sustained at a high level after stimulation of PC12 cells with nerve growth factor, PAE cells with serum, or Swiss 3T3 cells with PDGF. Dephosphorylation of Tyr 185 but not Thr 183 of p42mapk was suppressed by vanadate in EGF-stimulated PC12 cells; dephosphorylation of Thr 183, by contrast, was elicited by a vanadate-insensitive activity. Protein phosphatase-2A was the only vanadate-insensitive phosphatase acting on Thr 183 of p42mapk or on MAPKK to be detected in PC12 cell extracts. Phosphorylation of Thr 183 also inhibited the dephosphorylation of Tyr 185 in vitro by the major vanadate-sensitive Tyr 185-specific phosphatase, explaining why dephosphorylation of Thr 183 is rate-limiting for p42mapk inactivation in PC12 cells after stimulation with EGF.

CONCLUSIONS

The rapid inactivation of p42mapk initiated five minutes after stimulation of endothelial, adipose and chromaffin cells with growth factor is not catalysed by CL100, but rather by protein phosphatase 2A and by a protein tyrosine phosphatase distinct from CL100. Induction of CL100 is not accompanied by the inactivation of p42mapk in a number of situations.

The threonine residues in MAP kinase kinase 1 phosphorylated by MAP kinase in vitro are also phosphorylated in nerve growth factor-stimulated rat phaeochromocytoma (PC12) cells

The residues on MAP kinase kinase-1 (MAPKK1) phosphorylated by MAP kinase in vitro have been identified as Thr-291 and Thr-385. Both threonines are phosphorylated in PC12 cells and the 32P-labelling of each residue increases after stimulation with nerve growth factor (NGF). The results establish that MAPKK1 is a physiological substrate for MAP kinase. The two active forms of MAPKK that are resolved by Mono Q chromatography of PC12 cell extracts are both phosphorylated at Thr-291 and Thr-385, demonstrating that neither species is the MAPKK2 isoform which lacks Thr-291.

The protein kinase mos activates MAP kinase kinase in vitro and stimulates the MAP kinase pathway in mammalian somatic cells in vivo

The mos protooncogene encodes a serine/threonine protein kinase that is only expressed at significant levels in germ cells. Recombinant malE-mos protein (Xenopus mos protooncogene fused in frame to the maltose binding protein of E. coli) activates MAP kinase in cell-free extracts prepared from Xenopus oocytes and eggs. Here we show that malE-mos immunoprecipitates from Xenopus extracts phosphorylate and activate MAP kinase kinase in vitro, indicating that mos can function as a MAP kinase kinase kinase. Moreover, ectopic expression of mos in mammalian somatic cells, that lack any endogenous mos protein, triggers the activation of MAP kinase in vivo. These results identify the mos protooncogene as a direct activator of the MAP kinase pathway, with the potential to activate this kinase cascade even in cells where normally there is no expression of mos.

Identification of a MAP kinase kinase kinase in phaeochromocytoma (PC12) cells

A MAP kinase kinase kinase (MAPKKK) was identified in phaeochromocytoma (PC12) cells which reactivated homogeneous MAP kinase kinase (MAPKK) from rabbit skeletal muscle that had been inactivated by incubation with protein phosphatase 2A. Reactivation was accompanied by stoichiometric phosphorylation of MAPKK on a serine residue(s). Following stimulation of PC12 cells with nerve growth factor and chromatography of the extracts on Mono Q, MAP kinase and MAPKK were detected as active phosphorylated enzymes, whereas MAPKKK was inactive and only activated after prolonged storage at 4 degrees C. The results suggest that the activation of MAPKKK by growth factors is likely to occur by a non-covalent mechanism.

Sustained activation of the mitogen-activated protein (MAP) kinase cascade may be required for differentiation of PC12 cells. Comparison of the effects of nerve growth factor and epidermal growth factor

Stimulation of PC12 cells with nerve growth factor (NGF) increased mitogen-activated protein kinase kinase (MAPKK) activity > 20-fold after 5 min to a level that was largely sustained for at least 90 min. MAPKK activity was stimulated to a similar level by epidermal growth factor (EGF), but peaked at 2 min, declining thereafter and returning to basal levels after 60-90 min. Activation of MAPKK by either growth factor occurred prior to the activation of MAP kinase, consistent with MAPKK being the physiological activator of MAP kinase. The results demonstrate that the transient activation of MAPKK by EGF and its sustained activation by NGF underlies the transient and sustained activation of MAP kinase induced by EGF and NGF respectively. NGF or EGF induced the same two forms of MAPKK that were resolved on a Mono Q column. The Peak-1 MAPKK was activated initially and partially converted into the more acidic peak-2 MAPKK after prolonged growth-factor stimulation. The Peak-2 MAPKK was 20-fold more sensitive to inactivation by the catalytic subunit of protein phosphatase 2A. Stimulation with NGF caused a striking translocation of MAP kinase from the cytosol to the nucleus after 30 min, but not nuclear translocation of MAP kinase occurred after stimulation with EGF. The results suggest that sustained activation of the MAP kinase cascade may be required for MAP kinase to enter the nucleus, where it may initiate the gene transcription events required for neuronal differentiation of PC12 cells.

HLA-DQA1 and MLC among HLA (generic)-identical unrelated individuals

We modified a previously published PCR-RFLP for DQA1 typing (1) and examined the predictive value of HLA-DQA1 in mixed lymphocyte cultures (MLC) among matched (HLA generic types) pairs of unrelated individuals. There were 61/102 (60%) pairs with positive MLC, one-third of which could be predicted by DQA1* typing alone. DQA1 matching and MLC reactions were classified into 3 groups: 1) DQA1 mismatches showing positive MLC: 19/102 (19%); 2) DQA1 matches showing negative MLC: 41/102 (40%); 3) DQA1 identical showing positive MLC: 42/102 (41%). Five different HLA haplotypes that result from non-random association of HLA generic types (high delta haplotypes) were overrepresented in the individuals tested. One of these haplotypes carrying HLA-B7, DR2 was found associated with three different DQA1 alleles (*0201, *0103, *0102). The remaining four high delta haplotypes were associated with one DQA1 allele in all independent examples tested: HLA-A1, B8, DR3 with DQA1*0501; HLA-A26, B38, DR4 with DQA1*0301; HLA-A2, Bw62, DR4 with DQA1*0301 and HLA-A1, Bw57, DR7 with DQA1*0201. Forty per cent of the negative MLC were explained in part by the excessive number of individuals carrying two of these four haplotypes, which probably carry determinants in linkage disequilibrium with HLA. Nineteen per cent of HLA-identical (generic types) unrelated pairs show positive MLC reactions and all of them are DQA1* mismatched, suggesting that DQA1* allele typing should be used to screen samples prior to performing MLC.

[Free myocutaneous flap of the latissimus dorsi in cervicofacial surgery]

Free myocutaneous latissimus dorsi transplants are exceptionally used in cervicofacial surgery. The authors have performed an anatomical study of 23 non-embalmed subjects, using injections of neoprene latex and barium sulfate into the axillary artery and dye injections. Dissections, arteriographs and corrosion show that the lower scapular pedicle is constant, with an average length of 9.5 cm and a caliber that is sufficient for vasuclar microsurgery. Eight patients with large T4 cervicocephalic neoplasms were operated, including two with tongue tumors, one with a tumor of the oropharynx, two oromandibular lesions, two lesions of the maxillary sinus and a neuroblastoma involving the middle level of the facial structures. A free myocutaneous latissimus dorsi transplant was used. The transplant was revascularised by neck vessels using microsurgical techniques. Complete success was obtained in all eight patients. Good functional, cosmetic and morphological results were obtained as a rule. In cervicofacial surgery, the authors have thus chosen and used a free myocutaneous latissimus dorsi transplant in three topographic indications: for the oropharynx, to fill large cavities, especially the maxillary sinus, and to fill the middle level of the facial structures and of the base of the skull.

Investigations of the possible glycosylation of monoamine oxidase B from pig leucocytes

Monoamine oxidase B (MAO B) from pig liver has been reported to be a sialoglycoprotein. However, when that enzyme from pig lymphocytes and granulocytes was separated by polyacrylamide gel electrophoresis after labelling with the specific irreversible inhibitor [3H]pargyline, staining with 1-ethyl-2-[3-(1-ethyl-naphtho [1,2d] thiazolin-2-ylidene)-2-methylpropenyl] naphtho [1,2d] thiazolium bromide ("Stains-all") failed to detect the presence of sialic acid residues. Treatment of the enzyme in disrupted lymphocytes and granulocytes, or in mitochondrial fractions prepared from them, with neuraminidase resulted in a decrease in MAO activity. However, after the enzyme was rendered soluble by treatment with octylglucoside, treatment with neuraminidase had no effect on the activity. These results indicate that sialic acid residues are not an intrinsic component of MAO B, although associated material containing such groups appears to affect the activity of the membrane-bound enzyme. The activities of membrane-bound preparations of MAO B from pig lymphocytes and granulocytes were unaffected by treatment with trypsin or beta-chymotrypsin. After the preparations had been rendered soluble by treatment with octylglucoside there was a decrease in the activity on treatment with beta-chymotrypsin, but trypsin treatment had no effect. Thus solubilization resulted in residues sensitive to cleavage by the former enzyme becoming accessible to it. Tryptic and chymotryptic peptides separated from the sodium dodecyl sulphate denatured enzymes by polyacrylamide gel electrophoresis revealed no differences between MAO B prepared from lymphocytes and granulocytes.

Determination of monoamine oxidase concentrations in rat liver by inhibitor binding

The concentrations of monoamine oxidase-A and -B have been determined in mitochondria, mitochondrial outer membranes and microsomes from Sprague-Dawley and Wistar rats by determining the binding of tritium-labelled pargyline. Although the amounts of each form present depended on the source and the preparation method, this was paralleled by the specific activity such that the molecular turnover number was found to remain constant. The catalytic constants, kcat/Km, which represents the apparent second-order rate constant for the combination of enzyme and substrate, were about 0.13 and 2.1 sec-1 X microM-1 for 5-hydroxytryptamine and 2-phenethylamine, respectively, regardless of the source. Estimations of the amounts of the two forms by determining the concentrations of the inhibitors clorgyline, (-)-deprenyl, J-508 or pargyline necessary to give complete inhibition were shown to give overestimates of the true values because of the non-specific binding of these inhibitors to sites other than the monoamine oxidase active site.

Professional and lay observers' impressions of preschoolers wearing hearing aids

This study determined whether professional and lay observers had similar impressions of preschoolers wearing hearing aids and if the size of the aid affected ratings. Stimuli consisted of three photographic slides of nine normally-hearing and speaking male preschoolers wearing (1) a body-type hearing aid, (2) a post-auricular type aid, and (3) no aid. Slides were accompanied by taped speech samples. Stimuli were presented to 75 professional and 75 lay observers who rated the children on a semantic differential scale containing 15 adjectives. Ratings were submitted to a factor analysis revealing Factor I as achievement and Factor II as appearance. Results of MANOVAs revealed that neither professional nor lay observers discriminated against the children on appearance regardless of the presence of a hearing aid, but that both groups rated them significantly poorer on achievement when an aid was present. Lay observers' ratings showed a bias against the size of the aid, while professionals exhibited negative impressions whenever an aid was present, regardless of its size. These findings indicate that the "hearing aid effect" was present on variables of achievement even for normal-hearing preschoolers.

Lobomycosis. An electronmicroscopic, histochemical and immunologic study

A 73-year-old woman from Guyana had nodular keloidal lesions on her face which had persisted for 56 years. A biopsy of the lesion revealed lobomycosis, a rare fungal infection. Microscopically, numerous fungi were seen in giant cells and macrophages. The macrophages had abundant pink reticulated cytoplasm. These macrophages in lobomycosis, considered by some in the past to be granular myoblastoma cells, were rich in glycoproteins and appeared to be "Gaucher-like cells" in electronmicrographs. Further, a transition of macrophages containing organisms to Gaucher-like cells was noted. Antibodies to the fungus were demonstrated in the patient's serum by counter immunoelectrophoresis and indirect immunofluorescence studies. We postulate that the Gaucher-like cells formed because of the inability of host macrophages to digest glycoproteins in the capsule of this unusual fungus.