Association Between Vision and Hearing Impairments and Their Combined Effects on Quality of Life

OBJECTIVES

To assess associations between age-related vision and hearing impairments and whether combined sensory losses magnify effects on health-related quality of life.

METHODS

Seventy-five percent of survivors (n = 2334) were reexamined at Blue Mountains Eye Study 5-year examinations and 86.3% (2015) attended hearing assessments. Visual impairment was defined as visual acuity less than 20/40 (better eye), and hearing impairment as average pure-tone air conduction threshold greater than 25 dB (500-4000 Hz, better ear).

RESULTS

Persons with visual impairment, compared with those without visual impairment, had lower mean audiometric thresholds across all frequencies (P< or =.05). For each 1-line (5-letter) reduction in best-corrected visual acuity and presenting visual acuity, hearing loss prevalence increased by 18% and 13%, respectively. Cataract and age-related maculopathy were also associated with hearing loss (respectively, multivariate-adjusted odds ratio, 1.3 and 1.6; 95% confidence interval, 1.0-1.7 and 1.1-3.1). The association between age-related maculopathy and hearing loss was stronger at younger ages (<70 years). Combined impairments were associated with poorer health-related quality of life than were single impairments (multivariate-adjusted 36-Item Short-Form Health Survey mean physical and mental component scores; Ptrend = .001 and <.001, respectively).

CONCLUSIONS

Older persons with visual impairment were also more likely to have hearing loss in this study, which suggests that these sensory impairments could share common risk factors or biologic aging markers. Combined sensory impairments also cumulatively affect health-related quality of life.

Odds of demonstrating auditory processing abnormality in the average older adult: the Blue Mountains Hearing Study

OBJECTIVE

To determine, for the average older adult, the odds of demonstrating an auditory processing abnormality for each of seven speech-based measures of auditory processing and how these odds vary based on a number of independent subject variables.

DESIGN

Using a cross-sectional design, 1576 adults aged 55 years and older were assessed with speech measures of central auditory processing and questionnaires pertaining to health status, cognitive and perceived auditory function. The speech-based measures from which abnormal/normal outcomes were derived were (a) right ear Macquarie Synthetic Sentence Identification (MSSI) test maximum performance score (Rt MSSImax), (b) left ear MSSI test maximum performance score (Lt MSSImax), (c) right ear Macquarie Dichotic Sentence Identification (MDSI) test score (Rt MDSI), (d) left ear MDSI test score (Lt MDSI), (e) difference score for the right and left ear MDSI test (MDSI Diff score), (f) right ear MSSI test maximum performance score subtracted from the maximum performance score for monosyllabic word list materials in the same ear (Rt PB-MSSImax), and (g) left ear MSSI test maximum performance score subtracted from the maximum performance score for monosyllabic word list materials in the same ear (Lt PB-MSSImax).

RESULTS

The odds of demonstrating auditory processing abnormality for average older participants, increased by 4 to 9% per year of age. Men were approximately twice as likely as women to demonstrate this abnormality, but the gender difference was only evident with dichotic measures. With increasing hearing handicap, the odds of demonstrating auditory processing abnormality increased, but this was only evident for speech-in-noise measures. With subtle cognitive decline, the odds of demonstrating auditory processing abnormality also increased.

CONCLUSIONS

This population-based study provides evidence of a link between perceived hearing handicap and outcomes on speech-in-noise measures as well as evidence of a gender difference that became apparent using dichotic tests. The contribution of central auditory processing abnormality to hearing health should therefore not be overlooked in the provision of auditory rehabilitation programs to older adults.

Risk factors for tinnitus in a population of older adults: the blue mountains hearing study

OBJECTIVE

To identify potential and modifiable risk factors for tinnitus in a population of older adults.

STUDY DESIGN

Cross-sectional study. Detailed questionnaires were interviewer-administered in a representative sample of 2015 persons aged 55+ yr, living in an area west of Sydney, Australia. Air- and bone-conduction audiometric thresholds were measured from 250 to 8000 Hz and from 500 to 4000 Hz, respectively. TEOAE and SOAE were measured for both ears.

RESULTS

After adjusting for multiple variables in a Cox proportional hazards model, factors that significantly increased the risk of tinnitus were poorer hearing and cochlear function, self-reported work-related noise exposure, and history of middle ear or sinus infections, severe neck injury or migraine.

CONCLUSION

Interventions aimed at reducing age-related hearing loss, particularly by reducing excessive work-related noise exposure, and the effective, timely treatment of ear-related infections, may all decrease the risk of tinnitus.

Prevalence and characteristics of tinnitus in older adults: the Blue Mountains Hearing Study

There have been few recent estimates of the prevalence of tinnitus from large population-based samples of older persons. Our study aimed to assess the prevalence and characteristics of prolonged tinnitus in a representative sample of 2015 adults aged 55-99 years, residing in the Blue Mountains, west of Sydney, Australia, during 1997-99. All participants underwent a detailed hearing examination by an audiologist, including comprehensive questions about hearing. After age adjustment, subjects reporting tinnitus had significantly worse hearing at both lower and higher frequencies (p < 0.001). This difference was more marked in younger than in older subjects (p < 0.05). Overall, 602 subjects (30.3%) reported having experienced tinnitus, with 48% reporting symptoms in both ears. Tinnitus had been present for at least 6 years in 50% of cases, and most (55%) reported a gradual onset. Despite tinnitus being described as mildly to extremely annoying by 67%, only 37% had sought professional help, and only 6% had received any treatment.

Effect of nonnicotine pharmacotherapy on smoking behavior

Smoking-related disease is the single biggest preventable cause of morbidity and mortality in the United States, yet approximately 25% of Americans continue to smoke. Various dosage forms of nicotine replacement therapy increase smoking quit rates relative to placebo, but they generally do not result in 1-year quit rates of over 20%. To increase these rates, a number of nonnicotine agents have been investigated. Drugs that modulate noradrenergic neurotransmission (bupropion, nortriptyline, moclobemide) are more effective than those affecting serotonin (selective serotonin reuptake inhibitors, buspirone, ondansetron) or other neurotransmitters.

Validation of self-reported hearing loss. The Blue Mountains Hearing Study

PURPOSE

Large-scale epidemiological studies have often used self-report to estimate prevalence of age-related hearing loss. However, few large population-based studies have validated self-report against measured hearing loss. Our study aimed to assess the performance of a single question and a brief hearing handicap questionnaire in identifying individuals with hearing loss, against the gold standard of pure-tone audiometry.

METHODS

We examined 2015 residents, aged 55-99 years, living in the west of Sydney, Australia, who participated in the Blue Mountains Hearing Study during 1997-1999. Audiologists administered a comprehensive questionnaire, including the question: 'Do you feel you have a hearing loss?' The Shortened Hearing Handicap Inventory for Elderly (HHIE-S) was also administered during the hearing examination, which included pure-tone audiometry. The single question and HHIE-S were compared with measured losses at levels >25, >40 and >60 decibels hearing level (dBHL) to indicate mild, moderate and marked hearing impairment, for pure-tone averages (PTA) of responses to 500, 1000, 2000 and 4000 Hz.

RESULTS

The single question yielded reasonable sensitivity and specificity for hearing impairment, and was minimally affected by age and gender. HHIE-S scores >8 had lower sensitivity but higher specificity and positive predictive value. The HHIE-S performed slightly better in younger than older subjects and performed better for moderate hearing impairment.

CONCLUSIONS

In this older population with a high prevalence of hearing loss (39.4%), both a question about hearing and the HHIE-S appeared sufficiently sensitive and specific to provide reasonable estimates of hearing loss prevalence. Both could be recommended for use in epidemiological studies that aim to assess the magnitude of the burden caused by age-related sensory impairment but cannot measure hearing loss by audiometry.

A major susceptibility locus for leprosy in India maps to chromosome 10p13

Leprosy, a chronic infectious disease caused by Mycobacterium leprae, is prevalent in India, where about half of the world's estimated 800,000 cases occur. A role for the genetics of the host in variable susceptibility to leprosy has been indicated by familial clustering, twin studies, complex segregation analyses and human leukocyte antigen (HLA) association studies. We report here a genetic linkage scan of the genomes of 224 families from South India, containing 245 independent affected sibpairs with leprosy, mainly of the paucibacillary type. In a two-stage genome screen using 396 microsatellite markers, we found significant linkage (maximum lod score (MLS) = 4.09, P < 2x10-5) on chromosome 10p13 for a series of neighboring microsatellite markers, providing evidence for a major locus for this prevalent infectious disease. Thus, despite the polygenic nature of infectious disease susceptibility, some major, non-HLA-linked loci exist that may be mapped through obtainable numbers of affected sibling pairs.

Differentially expressed genes in hormone refractory prostate cancer: association with chromosomal regions involved with genetic aberrations

Differential gene expression between the androgen sensitive human prostate cancer cell line LNCaP and an insensitive clonal variant, LNCaP-r, was demonstrated by suppression subtractive hybridization. Twenty-one sequences were identified of which 9 are homologous to known genes, 11 are represented by expressed sequence tags (ESTs), and 1 is novel. We present data for 5 of 7 sequences confirmed to be differentially expressed by Northern blot analysis and semiquantitative RT-PCR. Only one gene, fibronectin (FN), was highly overexpressed (>60-fold) in LNCaP-r cells, consistent with previously reported overexpression of FN in prostate cancer. Four sequences were down-regulated in LNCaP-r cells, including an inactive variant of the E2 ubiquitin conjugating enzyme (UEV-1), a novel metalloproteinase-related collagenase (PM5), and a potential tumor suppressor gene (breast basic conserved gene, BBC1). UEV-1 is multifunctional, regulates the cell cycle via cdk1, has homology to MMS2 and likewise functions as a DNA protection protein, and also has homology to TSG101. Aberrant splice variants of TSG101 occur frequently in both breast and prostate cancer, but its mechanism of action is unknown. FN, BBC1, and UEV-1 localize to regions of chromosomal aberration (2q3.4, 16q24.3, and 20q13.2, respectively) associated with advanced prostate cancer and thus may be highly relevant to disease progression.

Augmentation of the early phase of liver regeneration after 70% partial hepatectomy in rats following selective Kupffer cell depletion

BACKGROUND/AIMS

Kupffer cells are located in the liver sinusoids adjacent to hepatocytes and elaborate a range of growth regulatory molecules involved in regulating hepatocyte proliferation. In vitro observations imply the potential for Kupffer cells to exert both stimulatory and inhibitory influences on hepatocyte DNA synthesis. We aimed to determine the overall effect of Kupffer cell activity during the early regenerative processes after partial hepatectomy.

METHODS

We investigated hepatocyte DNA synthesis, induced by partial hepatectomy in rats, following selective elimination of Kupffer cells by liposome encapsulated dichlormethylene bisphosphonate (Cl2MBP).

RESULTS

We demonstrate that the early phase of liver regeneration was enhanced following Kupffer depletion, as indicated by a greater proportion of hepatocytes undergoing DNA synthesis, and a higher mitotic index. This was associated with an alteration in the balance of growth factors in the liver; HGF and TGFbeta mRNA were reduced in Kupffer cell-depleted animals, and IL-1beta mRNA was absent. In addition, in the absence of partial hepatectomy, the selective depletion of Kupffer cells leads to an increase in the proliferation of hepatocytes in resting liver undergoing DNA synthesis.

CONCLUSION

The overall effect of depleting the liver of Kupffer cells is to enhance the proliferation rate of hepatocytes, both after partial hepatectomy and in the resting state.

Wound healing in the liver with particular reference to stem cells

The efficiency of liver regeneration in response to the loss of hepatocytes is widely acknowledged, and this is usually accomplished by the triggering of normally proliferatively quiescent hepatocytes into the cell cycle. However, when regeneration is defective, tortuous ductular structures, initially continuous with the biliary tree, proliferate and migrate into the surrounding hepatocyte parenchyma. In humans, these biliary cells have variously been referred to as ductular structures, neoductules and neocholangioles, and have been observed in many forms of chronic liver disease, including cancer. In experimental animals, similar ductal cells are usually called oval cells, and their association with impaired regeneration has led to the conclusion that they are the progeny of facultative stem cells. Oval cells are of considerable biological interest as they may represent a target population for hepatic carcinogens, and they may also be useful vehicles for ex vivo gene therapy for the correction of inborn errors of metabolism. This review proposes that the liver harbours stem cells that are located in the biliary epithelium, that oval cells are the progeny of these stem cells, and that these cells can undergo massive expansion in their numbers before differentiating into hepatocytes. This is a conditional process that only occurs when the regenerative capacity of hepatocytes is overwhelmed, and thus, unlike the intestinal epithelium, the liver is not behaving as a classical, continually renewing, stem cell-fed lineage. We focus on the biliary network, not merely as a conduit for bile, but also as a cell compartment with the ability to proliferate under appropriate conditions and give rise to fully differentiated hepatocytes and other cell types.

Influence of Alcohol on Stability of Oil-in-Water Emulsions Containing Sodium Caseinate

The effect of alcohol on the stability of oil-in-water emulsions of similar mean droplet size made with 4 wt% sodium caseinate and 35 vol% n-tetradecane was investigated. Controlled stress viscometry showed that, shortly after preparation, emulsions containing 25 vol% ethanol are of low viscosity and almost Newtonian in character. In contrast, emulsions containing little or no alcohol (</=10 vol%) exhibit psuedoplastic behavior with a much higher limiting low-stress viscosity. Time-dependent creaming profiles were determined at 30&deg;C using an ultrasound velocity scanning technique with a linear renormalization data analysis. The addition of alcohol was found to have relatively little effect on the long-term creaming stability, which was uniformly characteristic of a flocculated emulsion. The presence of alcohol leads to Ostwald ripening, as demonstrated by the gradual shift in monomodal droplet-size distribution during prolonged storage. Ostwald ripening is probably the main reason for the stepwise reduction in oil concentration in the serum phase of the stored alcohol-containing emulsions. Time-dependent rheology measurements of alcohol-rich emulsions showed an apparent shear viscosity increasing steadily over a matter of hours, suggesting that flocculation was not eliminated, but merely slowed, by the presence of the alcohol. It is proposed that the presence of alcohol modifies the average size and composition of the unadsorbed caseinate submicelles which are putatively responsible for the depletion flocculation. Reducing the mean diameter of droplets in alcohol-containing emulsions by prolonged homogenization was found to enhance the short-term emulsion creaming stability, but the long-term stability was essentially unaffected due to the predominant influence of Ostwald ripening. Copyright 1998 Academic Press. Copyright 1998Academic Press

Liver stem cells: when the going gets tough they get going

The ability of the liver to regenerate is widely acknowledged, and this is usually accomplished by the entry of normally proliferatively quiescent hepatocytes into the cell cycle. However, when hepatocyte regeneration is impaired, small bile ducts proliferate and invade into the adjacent hepatocyte parenchyma. In humans and experimental animals these ductal cells are referred to as oval cells, and their association with defective regeneration has led to the belief that they are the progeny of facultative stem cells. Oval cells are of great biological interest since they may represent a target population for hepatic carcinogens, and they may also be useful vehicles for ex vivo gene therapy for the correction of inborn errors of metabolism. The ability of oval cells to differentiate into hepatocytes has been demonstrated unequivocally. However, this process only occurs when the regenerative capacity of hepatocytes is overwhelmed, and thus, unlike the intestinal epithelium, the liver is not behaving as a classical continually renewing stem cell-fed lineage.

Rheology of Sodium Caseinate Stabilized Oil-in-Water Emulsions

We report on shear rheological measurements at 30&deg;C of fine oil-in-water emulsions (volume-surface average diameter < 0.5 &mgr;m) prepared at pH 6.8 with sodium caseinate as the sole emulsifier (1-6 wt%) and n -tetradecane as the dispersed phase (10, 35, or 45 vol%). Strong sensitivity of rheological behavior to total protein concentration was indicated by both steady-state viscometry and small-deformation oscillatory experiments. The behavior can be classified into three types, depending on the protein/oil ratio. (1) Emulsions containing insufficient protein for (near-) saturation protein surface coverage develop a time-dependent increase in low-stress apparent viscosity and associated shear-thinning behavior; this can be attributed to bridging flocculation. (2) Emulsions having full protein surface coverage but relatively little excess unadsorbed protein in the continuous phase are stable Newtonian liquids. (3) Emulsions containing a substantial excess of unadsorbed sodium caseinate exhibit considerable pseudoplasticity which can be attributed to depletion flocculation. Taken as a whole, the time-dependent rheological properties for this set of emulsions as a function of protein content and oil volume fraction are largely consistent with our previous results on the creaming stability and the particle gel microstructure for these same emulsion systems. In particular, the reversible flocculation of emulsion samples of high protein content is readily explicable in terms of depletion flocculation of droplets by unadsorbed protein existing in the form of approximately spherical caseinate submicelles.

Wholesale hepatocytic differentiation in the rat from ductular oval cells, the progeny of biliary stem cells

BACKGROUND/AIMS

Biliary epithelial cells (ductular oval cells) migrate into the periportal and midzonal parenchyma when hepatocyte regeneration after injury is significantly impeded. The potential of oval cells to differentiate into hepatocytes has been questioned. We have sought to resolve this issue using the modified Solt-Farber procedure in which 2-acetylaminofluorene is used to block hepatocyte regeneration in partially hepatectomized rats.

METHODS

Rats received 2-acetylaminofluorene by oral gavage for 6 days before and up to 7 days after a two-thirds hepatectomy. The cellular reaction was visualized by the immunohistochemical localization of intermediate filaments cytokeratins 8 and 19 and vimentin, cytochrome P450 enzymatic proteins and alpha-foetoprotein. Expression of albumin and alpha-foetoprotein mRNA transcripts were observed in situ using antisense riboprobes.

RESULTS

During the first 9 days after partial hepatectomy long strings of ductular cells spread outwards from the portal areas. These cells exhibited strong diffuse cytoplasmic staining with the anticytokeratin 8 and 19 antibodies, like authentic bile ducts, but in addition also expressed vimentin and alpha-foetoprotein (protein and mRNA)-collectively termed the "oval cell phenotype". Thereafter, these ducts rapidly vanished to be replaced by basophilic hepatocytes which lacked the oval cell phenotype, but which acquired strong expression of albumin mRNA. At 14 days after partial hepatectomy the oval cell phenotype was restricted to the peripheral margins of the newborn periportal hepatocytes, the distal tips of the oval cell ducts, and these too had disappeared within another 7 days.

CONCLUSIONS

Ductular oval cells will differentiate into hepatocytes under appropriate experimental conditions.

Creaming and Flocculation of Oil-in-Water Emulsions Containing Sodium Caseinate

The influence of protein content on the stability of concentrated oil-in-water emulsions (35 or 45 vol% oil, droplet diameter approximately 0.5 &mgr;m, pH 6.8) containing sodium caseinate as the sole emulsifying agent has been investigated. Time-dependent creaming profiles were determined at 30&deg;C using an ultrasound velocity scanning technique with data analysis based on a Urick equation renormalization technique. The results indicate that creaming kinetics has a complex dependence on caseinate content. At low protein content (1 wt%), corresponding to less than half that required for saturation monolayer coverage, the emulsion is destabilized by bridging flocculation (accompanied by some coalescence). At higher protein content (2 wt%), where individual droplets are fully protected against protein bridging or coalescence by the thick adsorbed protein layer, the unflocculated emulsion has good stability over a period of several weeks. With further increase of protein content (>/=3 wt%), the observed creaming stability is reduced again, with the rate of serum separation at the bottom of the sample now greatly increased. This is attributed here to depletion flocculation by unadsorbed caseinate, probably in the form of small particles called "casein submicelles." Light microscopy has confirmed that the visually observable extent of reversible depletion flocculation in concentrated emulsions of this type is very sensitive to overall protein content. Once the caseinate concentration reaches a high value (6 wt%), the strength of the depletion interaction is such that it produces a very strong emulsion droplet network which can reorganize only slowly, and is hence much more stable to creaming and serum separation.

Reactive biliary epithelium: the product of a pluripotential stem cell compartment?

Liver parenchymal cells (hepatocytes) have a low rate of turnover, but can nevertheless mount a rapid and efficient regenerative response. However, in some cases of extreme hepatotoxicity hepatocyte proliferation is restricted or even abolished, and instead biliary epithelial cells, commonly referred to as ductular oval cells, migrate into the periportal and midzonal parenchyma. Initially these cells behave as authentic biliary epithelium with expression of the biliary cytokeratin intermediate filaments, but then show hepatocytic traits such as alpha fetoprotein and albumin synthesis. Thereafter these biliary ducts rapidly vanish to be replaced by either small hepatocytes or intestinal-type cells. The proliferation and differentiation of oval cells is probably strongly influenced by paracrine signalling from liver stellate cells. Oval cells appear to be the progeny of facultative pluripotential stem cells which have the lineage potential of uncommitted gastrointestinal stem cells; these stem cells are likely to be located in the cholangioles and small interlobular bile ducts. Oval cells thus constitute an important reserve compartment for hepatocytes when hepatocyte regeneration is compromised.

Liver damage in the rat induces hepatocyte stem cells from biliary epithelial cells

BACKGROUND & AIMS

When rat hepatocyte regeneration after partial hepatectomy is blocked by 2-acetylaminofluorene, a proliferation of biliary epithelia sends out ductules into the parenchyma. The ability of these neoductules to act as a significant progenitor compartment for hepatocytes is in dispute. This study aims to resolve this question by varying the amount of 2-acetylaminofluorene administered.

METHODS

Rats were fed 2-acetylaminofluorene fr 6 days before and up to 7 days after partial hepatectomy was performed at a dose of either 2.5 (low) or 5 (high) mg/kg(-1)/day(-1). The response was monitored by the immunohistochemical expression of intermediate filaments and cytochrome P450 enzymes.

RESULTS

No regeneration by mature hepatocytes occurred with either dose, and new ductules expressed the biliary cytokeratins 7, 8, 18, and 19 and, in addition, vimentin. At the high dose, hepatocytic differentiation was infrequent, whereas apoptosis and intestinal differentiation were common. At the low dose, almost all ductules differentiated into hepatocytes within 14 days of hepatectomy.

CONCLUSIONS

Biliary epithelium is an effective and substantiative hepatocyte progenitor compartment under appropriate conditions.

Role of transforming growth factor-[beta]1 in inhibiting endothelial cell proliferation in experimental alcoholic liver disease

We used the intragastric feeding rat model for alcoholic liver disease to investigate the relationship between transforming growth factor (TGF)-beta 1 and inhibition of endothelial cell proliferation. Twelve groups of male Wistar rats (four to five rats per group) were fed ethanol or dextrose with either corn oil or saturated fat for 1-, 2-, and 4-week periods. All control animals were pair fed the same diets as ethanol-fed rats except that ethanol was isocalorically replaced by dextrose. In the ethanol-fed groups, nonparenchymal cells were isolated and TGF-beta 1 was measured in the nonparenchymal cell supernatant. Liver pathology and endothelial cell proliferation with an antibody to proliferating cell nuclear antigen were studied in all groups. Plasma TGF-beta 1 was measured in all rats. Pathological changes (fatty liver, necrosis, and inflammation) were observed only in the corn oil/ethanol-fed rats at 4 weeks. Significantly higher levels of TGF-beta 1 were seen in both plasma and nonparenchymal cell supernatant in rats fed corn oil and ethanol; plasma levels of TGF-beta 1 were not significantly different between the dextrose-fed controls and saturated fat/ethanol-fed rats. A significant inverse correlation (r = -0.89, P < 0.01) was seen between plasma TGF-beta 1 and the number of endothelial cells arrested at G1/S. Immunohistochemistry revealed the presence of TGF-beta 1 staining in interstitial macrophages only in rats fed corn oil and ethanol. The present study provides evidence for a role for TGF-beta 1 in inhibiting endothelial cell proliferation in experimental alcoholic liver disease. Arrest of endothelial cells may lead to their differentiation and/or to produce mediators that could stimulate other cells such as Ito cells. Sustained TGF-beta 1 may also lead to Ito cell production of extracellular matrix.

Establishment and characterisation of two cell lines derived from a primary adenocarcinoma of the duodenum

Aims-To establish two cell lines from a primary duodenal adenocarcinoma; to describe the morphological, growth, ploidy, and immunophenotypic characteristics of these cell lines.Methods-The cell lines, designated DAC/S and DAC/E, were characterised using both in vitro and in vivo cell culture techniques, light and electron microscopy, immunocytochemistry, and FACS analyses.Results-Both cell lines have an epithelial origin, are aneuploid and display characteristics of transformed cells. The cell lines differ from each other in morphology, doubling time and serum requirements. These cell lines are anchorage dependent and do not grow in nude mice.Conclusions-DAC/S and DAC/E cell lines are derived from neoplastic epithelium and could provide in vitro model systems for future investigations of the cell and molecular biology of duodenal neoplasia.

Protein extraction and western blotting from methacarn-fixed tissue

Polyacrylamide gel electrophoresis (PAGE) of proteins with subsequent western blotting has become a routine technique for the analysis of proteins from both cultured cells and fresh whole tissue. We have developed a method to extract proteins from methacarn-fixed tissue which renders them suitable for SDS-PAGE and western blotting. With a panel of antibodies to specific intermediate filaments, transforming growth factor-alpha (TGF-alpha), and albumin, immunohistochemistry was performed in parallel with western blotting on sections cut from methacarn-fixed samples of normal rat liver and liver from rats treated under a regime which induces oval cell proliferation. Immunohistochemistry enabled the determination of changes in tissue distribution and abundance of the target proteins, which was mirrored by the corresponding western blot data. This technique can be especially effective when used in conjunction with immunohistochemistry. Tissue samples are easy to prepare, avoiding the precautions which need to be taken when handling fresh tissue (Abstract: J Pathol 1994; 173S: No. 41).

Oval cell differentiation into hepatocytes in the acetylaminofluorene-treated regenerating rat liver

When hepatocyte regeneration after a two-thirds partial hepatectomy (PH) in rats is blocked by oral gavage of acetylaminofluorene, a proliferation of ductular cells ensues that results in a profusion of neoductules radiating from each portal tract. To examine the possibility that this population of newly emerging cells harbors cells capable of differentiating into hepatocytes, we have looked in these cells for expression of functional markers of hepatocyte commitment at both the RNA and protein levels. Expression of albumin and alpha-fetoprotein (alpha-FP) messenger RNA (mRNA) transcripts were sought in situ using antisense riboprobes, and the expression of a number of cytochrome P450 enzymes was examined immunohistochemically. Before any signs of differentiation the ductular cells strongly expressed cytokeratins 7, 8, 18, and 19 in the same manner as authentic bile ducts, but unlike the latter also expressed vimentin. In situ hybridization studies showed that small bile ducts close to the limiting plate, as well as the newly formed ducts, expressed albumin and alpha-fetoprotein messenger RNAs, and immunocytochemistry showed that the distribution of the respective proteins was similar. Beginning at 1 week after partial hepatectomy, areas of differentiation could be found in the new ducts, with cells resembling either columnar intestinal-type epithelia or hepatocytes. Intestinal-like cells expressed neither albumin, alpha-FP, nor cytochrome P450 enzymes, whereas ductular cells appearing like hepatocytes with the typical membranous distribution of cytokeratin 8 strongly expressed a variety of cytochrome P450 enzymes normally associated with functional hepatocytes. These observations further support the belief that reactive ductules, sprouted from small ducts, can represent an adaptive response of the liver to replenish lost hepatocytes, although some of the newborn cells appear to differentiate along intestinal lines.

The resistant hepatocyte model of carcinogenesis in the rat: the apparent independent development of oval cell proliferation and early nodules

The early cellular changes in the Solt-Farber resistant hepatocyte model of carcinogenesis have been studied to clarify the relationship of oval cell proliferation to the development of early hepatocyte nodules. Cellular proliferation, intermediate filament profiles and the expression of specific cytochrome P450 enzymes were examined. At 24 h after partial hepatectomy (PH) many of the bile ductular cells were in S phase, but over the next few days DNA synthesis progressively decreased in the portal bile ducts and was more common in arborizing ductules (oval cells) radiating from the portal areas. These cells strongly expressed cytokeratins 8 and 19 and vimentin, and from 1 week after PH they frequently underwent differentiation either into hepatocytes, expressing cytochrome P450 enzymes, or into intestinal-type cells. Five days after PH, numerous basophilic foci were discernible, and these expanded rapidly. The ductular cells swirled around the foci, but their antigenic profile clearly indicated that these cells were not involved in the development of these early nodules. In normal hepatocytes, cytokeratin 8 immunoreactivity was distinctly membranous in location, and could only be readily detected in periportal hepatocytes. In the basophilic hepatocyte foci, overexpression of cytokeratin 8 was consistently associated with cells organizing into acini, with expression reminiscent of authentic bile ducts, possibly indicating a structure-function relationship. In conclusion, early foci and nodules in this model are derived from resistant hepatocytes and not ductular oval cells, the latter being a facultative multipotential stem cell compartment.