A morphometric study of the endoplasmic reticulum in human hepatocytes. Correlation between morphological and biochemical data in subjects under treatment with certain drugs

Hepatic Enzyme Induction

Hepatic enzyme induction is generally an adaptive response associated with increases in liver weight, induction of gene expression, and morphological changes in hepatocytes. The additive growth and functional demands that initiated the response to hepatic enzyme induction cover a wide range of stimuli including pregnancy and lactation, hormonal fluctuations, dietary constituents, infections associated with acute-phase proteins, as well as responses to exposure to xenobiotics. Common xenobiotic enzyme inducers trigger pathways involving the constitutive androstane receptor (CAR), the peroxisome proliferator-activated receptor (PPAR), the aryl hydrocarbon receptor (AhR), and the pregnane-X-receptor (PXR). Liver enlargement in response to hepatic enzyme induction is typically associated with hepatocellular hypertrophy and often, transient hepatocyte hyperplasia. The hypertrophy may show a lobular distribution, with the pattern of lobular zonation and severity reflecting species, strain, and sex differences in addition to effects from specific xenobiotics. Toxicity and hepatocarcinogenicity may occur when liver responses exceed adaptive changes or induced enzymes generate toxic metabolites. These undesirable consequences are influenced by the type and dose of xenobiotic and show considerable species differences in susceptibility and severity that need to be understood for assessing the potential effects on human health from similar exposures to specific xenobiotics.

Ultrastructural changes in the liver of intravenous heroin addicts

The ultrastructural research has a decisive role in gathering the knowledge on the liver's response to the influence of some drugs. The aim of the study was to perform an ultrastructural analysis of the liver in chronic intravenous heroin addicts.The study involved the autopsy conducted on 40 bodies of intravenous heroin addicts and 10 control autopsies. The liver tissue was fixed in glutaraldehyde and moulded with epon for investigation purposes of ultrastructural changes. The analysis was performed using the method of transmission electron microscopy.In the group of intravenous heroin addicts, the liver autopsy samples showed degenerative vesicular and fat changes, chronic active and persistent hepatitis, cirrhosis, reduction in the amount of glycogen in hepatocytes, as well as the Kupffer cell's dominant hypertrophy. Various changes occur in organelles, plasma membrane of hepatocytes and biliary channels as well as in the nucleus. The most important ultrastructural findings include: hyperplasia and hypertrophy of the smooth endoplasmic reticulum, which is histologically proven vesicular degeneration of hepatocyte occurring as a result of the increased synthesis of enzymes of smooth endoplasmic reticulum due to chronic intravenous heroin intake, and the presence of continuous basal membrane followed by transformation of the sinusoids into capillaries (in the cases of chronic active hepatitis and cirrhosis) which leads to a disorder of microcirculation and further progress of cirrhosis.

Quantitative ultrastructural analysis of hepatoprotective effects of (+)-cyanidanol-3 on alcoholic liver damage

Biochemical considerations suggest that bioflavonoids may be effective antihepatotoxic and hepatoprotective agents. We, therefore, designed a morphometric study to examine the effect of (+)-cyanidanol-3 on ethanol-induced hepatocellular alterations. Using a stereologic point and intersection counting method we determined the volume fraction of cytoplasmic components, the surface area of cytoplasmic membranes, some parameters of mitochondria, and numerical densities of some organelles, after chronic ethanol intoxication and hepato-protective treatment of rats. Consistent with previous qualitative and quantitative descriptions, chronic ethanol feeding caused increases in parameters of mitochondria, microsome, and Golgi complex. The hepatoprotective (+)-cyanidanol-3 treatment restored most of the morphologic distortion caused by ethanol ingestion. The (+)-cyanidanol-3 treatment alone caused an elevation of the surface area of smooth endoplasmic reticulum and nonsignificant changes in mitochondrial parameters, possibly due to its inducing effect on microsomes and activating effect on mitochondrial enzymes. These data indicate that bioflavonoids could be of potential benefit in hepatotoxic or alcohol-related liver disease.

Influence of long-term anticonvulsant treatment on liver ultrastructure in man

In 35 patients on long-term anticonvulsant treatment (7-35 years, means = 19.6 years), various liver enzymes were measured. In 32 cases (91.4%), elevated levels of serum-gamma-glutamyl-transpeptidase (GGT) were found. Liver biopsy was performed in five of 13 patients with GGT levels of greater than 60 U/l (75-257, means = 123 U/l). Light microscopy showed a minimal steatosis and fine granular appearance of hepatocytes in two cases, and a slight portal fibrosis in one case. Two cases showed an unremarkable histology. Electron microscopy revealed signs of enzyme induction as overall swelling of the smooth endoplasmic reticulum and additionally a dilatation of the rough endoplasmic reticulum in all five specimens. No signs of liver damage or disturbance of liver function could be observed.

Changes induced in human liver by long-term anticonvulsant therapy. Functional and ultrastructural data

The study reports functional and morphological findings in eight male subjects undergoing anticonvulsant therapy for periods from 20 days up to 15 years. All subjects showed an increased activity of the hepatic microsomal NADPH cytochrome c reductase and an increased amount of smooth membranes in hepatocytes. The enzymatic activity was higher in the first years of treatment. Quantitative ultrastructural analysis showed that a twofold increase of the smooth membranes of hepatocytes had already been reached after 20 days of therapy, with a modest additional increase occurring thereafter. Both enzymatic and structural changes appear to be related to therapy. In addition, abnormal lipofuscin-related cytoplasmic formations were present in the hepatocytes of five subjects. Such formations are thought to represent an accumulation of abnormal degradation products, possibly related to an interaction of the drug(s) metabolites with cellular components.

[Postmortem evaluation of barbiturate poisonings]

The evaluation of barbiturate intoxication as the cause of death is often difficult when the concentration in body fluids and organs is not extremely high. The problem arises because of the great capacity of barbiturates to produce tolerance after chronic use, a property that is often unknown. Therefore, the most abused barbiturates were studied to assess whether chronic intake causes morphological liver changes or not. It was found that the chronic abuse of drugs containing seco-, cyclo-, brallo-, and/or pentobarbital produces hypertrophy of the smooth endoplasmic reticulum of hepatocytes corresponding to that of phenobarbital. Neither acute barbiturate overdose (without a history of abuse) nor chronic abuse of opiates causes similar liver changes. In conclusion, barbiturate tolerance can be evaluated postmortem by light microscopic examination of the liver.

The human liver in extrahepatic cholestasis: ultrastructural morphometric data

The present study reports the data obtained through a quantitative analysis performed on needle liver biopsies of five jaundiced patients with extrahepatic cholestasis. Whatever the duration of jaundice, the surface density of the smooth endoplasmic reticulum remained in the normal range in all subjects. The surface density of the rough endoplasmic reticulum was variable, showing elevated values in three of the five patients. The surface density of peroxisomes was unchanged with respect to controls. All the subjects exhibited an increase of the surface density of mitochondrial cristae without changes of the outer membrane. These data fail to show evidence of hypertrophy of the smooth endoplasmic reticulum in hepatocytes of human liver during extrahepatic cholestasis. Instead, the increased surface density of the mitochondrial cristae, which has also been previously reported in patients with uncomplicated cholelithiasis, appears as an early and constant phenomenon associated with conformational changes of this mitochondrial component. Such a structural modification might represent an elementary response of the liver cells to alterations in the pathways of synthesis and/or excretion of biliary components.

Effect of the triazolobenzodiazepine estazolam on hepatic drug-metabolizing enzyme activity in rats

Oral doses of the sedative/hypnotic estazolam (500 mg kg-1 day-1) to rats for 21 days caused statistically significant increases in liver weight, ascorbate excretion, cytochrome P-450 concentrations, and in aniline hydroxylase, ethylmorphine N-demethylase and glutathione S-transferase activities, as did approximately equivalent doses of flurazepam hydrochloride. Histologically, the centrilobular hepatocytes were enlarged. Some of these parameters were also increased after doses of estazolam of 100 mg kg-1 day-1, but not after 5 mg kg-1 day-1, which is about 50-fold greater than a clinical dose. Estazolam was a much less potent enzyme inducer than phenobarbitone under the conditions of these studies.

Hepatocyte localization of hepatitis B core and surface antigens in renal transplant recipients. An ultrastructural prospective study

A prospective series of 45 liver biopsies taken from 22 renal transplant patients was investigated for the presence of hepatitis B antigen core (HBc) and surface (HBs) components by electron microscopy. At the time of each biopsy serum HBs Ag was sought by radioimmunoassay. Sections were taken for the detection of HBs Ag by immunofluorescence. In seropositive patients, intravesicular tubular structures resembling HBs Ag were found in 61% of biopsies while the intranuclear core HBc was present in 69%. No correlation could be made between the ultrastructural pattern of the viral components and the intensity of the histological liver damage. During the follow up, there was an accumulation of both HBs and HBc Ag even in a period as short as 1 year. The 9 liver specimens examined after three years of transplantation showed a marked accumulation of both antigens. Thus the expression of HB Ag at the hepatocellular level seems to correlate better with the duration of antigenaemia than with the histological pattern. Lastly, on matched semithin and ultrathin sections, the ground glass appearance of cytoplasm appeared to correlate with smooth endoplasmic reticulum distorsion, irrespective of the simultaneous presence or absence of intravesicular tubular structures. The sanded nuclei expressed a rare massive accumulation of core antigen.

Electron microscopy: a method for the diagnosis of inherited metabolic storage diseases. Electron microscopy in diagnosis

In the diagnosis of inherited metabolic diseases, electron microscopy has become an important method complementary to clinical, histological and biochemical assays. The characteristic ultrastructure of stored material as well as the site of accumulation in the cell are shown in a number of metabolic disorders. The most prominent advantages of electron microscopical techniques as compared to alternative techniques are discussed. One of the advantages is the fact that ultrastructural investigation requires only tissue samples of very small size, and another that its results may be obtained within two days. Moreover, transmission electron microscopy permits new and promising analytical methods such as quantitative estimation of organellar changes (morphometry) and energy dispersive X-ray elemental analysis (EDX).

Stereological study of the zona fasciculata of the adrenal cortex in stress situations (hypothermia, catabolism)

The ultrastructure of the rat fasciculata cells in stress situations, such as catabolism and hypothermia was compared descriptively and quantitatively by stereological methods with that of the nonstimulated rat fasciculata cell. The volume and surface densities are expressed per cm3 of cytoplasm, mitochondria and smooth endoplasmic reticulum. Furthermore, absolute values are given. In both stress situations the volume density of the mitochondria compared to the controls is enlarged significantly (H: 37% CA: 50%). The significant increase of the average single mitochondrium of the fasciculata cell (H: 58% CA: 58%) shows a real growth of the mitochondria in these stress situations. Also the surface density of the mitochondrial inner membranes--the mitochondrial enzymes for steroid genesis are partly located in these membranes--shows a significant increase (H: 31%, CA: 84%). Whereas the volume density of the smooth endoplasmic reticulum remains unchanged, the surface density is significantly raised (H: 44%, CA: 60%). An attempt was made to draw up a relationship between stereological and known biochemical data of steroid genesis within the fasciculata cell. An activation in both stress situations could be observed. The stereological data reflect a subcellular reaction pattern, which is similar to exogenous ACTH administration, thus indicating an endogenous ACTH liberation due to these stress conditions.

Abnormal liver function in chronic hypervitaminosis A

A case of chronic hypervitaminosis A is reported in a 57-year-old woman who took vitamin preparations for alopecia. Liver biopsy of the patient showed both an increase in the number and size of fat-storing cells on light microscopy and rapidly fading green autofluorescence of vitamin A. Electron microscopy confirmed the presence of engorged fat-storing cells in the space of Disse and minor toxic changes in hepatocytes. This case illustrates the early hepatic changes of chronic hypervitaminosis A and indicates a need for restriction of sales of vitamin preparations.

Ultrastructure of periportal and centrilobular hepatocytes in human fatty liver of various aetiology

The ultrastructure of periportal and centrilobular hepatocytes of fatty liver from 2 alcoholic patients, 2 diabetic patients and 2 obese patients is described and compared with that of hepatocytes in 2 patients with normal liver. A striking difference between periportal and centrilobular hepatocytes in all cases of fatty liver is deomonstrated. The periportal hepatocytes contain abnormal mitochondria, while centrilobular hepatocytes have normal mitochondria, but fatty vacuoles, peroxisomes and lysosomes are more abundant. The nature and degree of ultrastructural changes showed no correlation with aetiology of the fatty liver. The normal livers showed no such changes or distinct differences between periportal and centrilobular hepatocytes.

Fatal hepatic coma complicating oxymetholone therapy in multiple myeloma

Two patients with multiple myeloma died in acute liver failure. Both had been treated with the anabolic steroid oxymetholone and both subsequently developed severe cholestatic hepatitis. In one the histological lesion progressed despite cessation of oxymetholone therapy. Myeloma infiltration of the liver and peliosis hepatis were not seen. As a fatal outcome from cholestatic hepatitis due to oxymetholone is rare it is possible that an unknown potentiating factor is present in multiple myeloma that can lead to a fatal outcome. If oxymetholone therapy is to be used in such patients then close clinical and laboratory assessment of liver function should be carried out in an attempt to prevent this unusual and fatal complication.

Quantitative microscopic evaluation of the endoplasmic reticulum in developing human liver

Quantitative electron microscopic aspects of the liver have not been explored in detail, and the numerical characterization of tissue changes may contribute to the understanding of basic cellular mechanisms in disease processes. Sixteen liver biopsies from children 2 months to 18 years old were analyzed by stereology to study the composition and relative distribution of endoplasmic reticulum membranes within hepatocytes. The histologic aspects of the liver as well as the clinical laboratory data of these patients revealed no abnormalities when being observed for suspected hepatic ailment. Morphometric analysis of four tissue blocks per biopsy was undertaken by means of combined light and electron microscopy, using standard stereologic formulae. The results showed less endoplasmic reticulum in liver cells from children 2 to 9 months old. These low levels were accounted for by reduced surface of smooth membranes. There was a first-order relationship in the growth of smooth endoplasmic reticulum between 2 months and 4 years at a rate of 17.1 sq cm/hr, similar to the membrane accumulation rate in experimental animals. Membrane dimensions from Golgi apparatus and rough endoplasmic reticulum were cell-size dependent, and these organelles matured within 2 months of postnatal life. The significance of these findings resides in the low amounts of smooth endoplasmic reticulum membranes at an early age. This lack of membrane surface agrees with findings in developing liver of various species. Experimental studies showed reduced membrane population and low microsome-bound enzyme activities which, under normal circumstances, allow the hepatocyte to undertake detoxification and drug metabolizing processes. Thus, the reduced membrane availability of the liver in infants may account for their inability to metabolize foreign compounds.

Hepatic cholesterol synthesis in man: effect of diazepam and other drugs

The hepatic synthesis of cholesterol-measured as incorporation of 14C-acetate into digitonin-precipitable sterols-has been evaluated in needle biopsy material of normal untreated patients and patients under short-term treatment with Diazepam, Phenobarbital, Chlorpromazine or Diphenylhydantoin. A significant increase of cholesterol synthesis was observed in the first two groups with much higher levels of incorporation in the Diazepam-treated patients. Moreover in this group the levels were still elevated from 4 to 7 days after drug withdrawl. Ultrastructural and morphometric studies performed on the same biopsy material showed a significant increase of smooth endoplasmic reticulum in hepatocytes of Diazepam-treated patients; in addition, there seemed to be a positive correlation between the increased cholesterol synthesis and the formation of areas of non vesicular, type 2, smooth endoplasmic reticulum. These findings suggest an early stimulation of the liver cell microsomal system by Diazepam in man; they also point to side effects of some drugs, which are not predictable from studies in Wistar rats.