Removed antibiotic-impregnated cement spacers in two-stage revision joint arthroplasty do not show biofilm formation in vivo

Use of antibiotic-impregnated spacers is common in the two-stage approach to treatment of periprosthetic joint infection despite the lack of information regarding in vivo performance of these implants. Antibiotic elution levels likely often fall below the minimal inhibitory concentration need to inhibit bacterial growth, raising concern that the spacers themselves may provide a potential attachment site for biofilm formation. Advanced microscopy was used in this study to evaluate the surface characteristics of antibiotic-eluting spacers collected at the time of prosthesis reimplantation from 6 patients undergoing two-stage treatment for an infected total joint arthroplasty. Scanning electron microscopy and confocal scanning microscopy of the removed spacers revealed modest fibrous matrix formation and inflammatory cells with no biofilm or bacteria detected. This study supports the continued use of antibiotic spacers in the treatment of periprosthetic joint infection.

A novel fixative for immunofluorescence staining of CD133-positive glioblastoma stem cells

Isolation of glioblastoma stem cells requires incubation of tumor cells in a neural stem cell media. Neurospheres containing these glioblastoma stem cells are formed after approximately a five-day period. These cells can then be analyzed for the presence of stem cell markers. Immunofluorescence staining for these markers can serve as a valuable tool for analyzing the intact neurosphere directly in stem cell media. Here we present the use of a novel fixative (1,4-benzoquinone) for immunoflourescence staining of neurospheres.

Hepatocellular ballooning in NASH

BACKGROUND & AIMS

Hepatocellular ballooning is a key finding in nonalcoholic steatohepatitis (NASH). It is conventionally defined by hemotoxylin and eosin (H&E) staining showing enlarged cells with rarefied cytoplasm and recently by changes in the cytoskeleton. Fat droplets are emerging as important organelles in cell metabolism. To address a possible relation between fat droplets and ballooning, we studied fat staining, H&E, and keratin 18 staining in human NASH.

METHODS

Sequential staining and high resolution imaging were used to study freshly prepared cryo-sections from 10 patients with histologically confirmed steatohepatitis using oil red O for fat droplet identification, H&E to identify ballooning, and anti-K18 to confirm cytoskeletal changes. High resolution images were captured at each stage using the Aperio Scanscope. To provide ultrastructural correlation, glutaraldehyde-fixed specimens were studied using transmission electron microscopy (TEM) with serial sectioning for localization of ballooned cells by light microscopy and TEM in identical specimens.

RESULTS

Serial staining consistently demonstrated that hepatocellular ballooning is associated with fat droplet accumulation evident by oil red O positivity and depletion of cytoplasmic keratin 18 with K-18 positive Mallory-Denk bodies (MDB). TEM confirmed the association between osmium stained fat droplets, MDB formation, and cellular enlargement and suggested droplet-associated dilation of the endoplasmic reticulum.

CONCLUSIONS

These results indicate a relationship between cellular ballooning, fat droplet accumulation, and cytoskeletal injury in NASH. We speculate that injury to multiple, organelles including fat droplets and endoplasmic reticulum, contribute to this characteristic finding.

Intramitochondrial crystalline inclusions in nonalcoholic steatohepatitis

Mitochondrial dysfunction is an important element in the pathogenesis of nonalcoholic steatohepatitis (NASH). Intramitochondrial crystals (IMCs) are a well-documented morphological abnormality seen on transmission electron microscopy in this disease. It has been suggested that IMCs consist of phospholipids, but their exact composition remain uncertain many years after their discovery. Micellar phase transitions of phospholipid bilayers is a well-known but little-studied phenomenon in living systems. Its presence in the mitochondria of NASH would offer significant insight into the disease with possible therapeutic implications. We postulated that intramitochondrial disturbances in NASH are sufficient to produce such transitions and that their detection in fresh biopsies would therefore be a dynamic process. To test this, we performed a blinded, prospective analysis of fresh liver biopsy samples immediately fixed under different conditions. Quantitative transmission electron microscopy morphometry, performed by systematically counting total mitochondria and IMCs within areas of uniform dimension, showed a stepwise decline in IMCs with cooler fixation temperature in each subject studied. Randomization testing (Monte Carlo resampling) confirmed that the detection of IMCs was strongly dependent on fixation temperature (P < 0.0001).

CONCLUSION

These results indicate that the intramitochondrial crystals characteristic of NASH are highly dynamic and unstable structures. The findings offer the strongest support yet for their origin in micellar phase transitions. We speculate that such transitions result from microenvironmental changes within the mitochondria and carry therapeutic implications, especially in regard to dietary manipulations of mitochondrial lipid composition.

The effects of 48 weeks of rosiglitazone on hepatocyte mitochondria in human nonalcoholic steatohepatitis

Rosiglitazone, a thiazolidinedione peroxisome proliferator-activated receptor gamma ligand, reduces disease activity in nonalcoholic steatohepatitis (NASH), a disease associated with hepatocyte mitochondrial crystalline inclusions that are not seen in animal models of NASH. In human and animal studies of adipose tissue, thiazolidinediones may induce mitochondrial biogenesis and associated morphological changes. To determine if rosiglitazone alters the hepatocyte mitochondrial morphology in human NASH, we prospectively and systematically examined liver biopsies from human subjects with NASH before and after 48 weeks of rosiglitazone by transmission electron microscopy. Twenty patients (body mass index = 34 +/- 7) were studied. Four coded sections from each of 20 pretherapy biopsies and each of 20 posttherapy biopsies were examined by transmission electron microscopy. The total hepatocyte mitochondria and crystal-containing mitochondria were counted, and semiquantitative scoring was performed for macrosteatosis, microsteatosis, dilated endoplasmic reticulum, apoptosis, Mallory bodies, and hepatocyte enlargement. The total mitochondria count was unchanged after therapy, but there was a significant increase in crystal-containing mitochondria from 4.0% (95% confidence interval = 1.8-8.8) to 7.2% (95% confidence interval = 3.9-12.6; odds ratio = 1.80; P = 0.04) after the treatment with rosiglitazone. Macrosteatosis (P < 0.001) and Mallory bodies (P = 0.05) significantly decreased, but no change was evident in microsteatosis, cellular enlargement, dilated endoplasmic reticulum, or apoptosis.

CONCLUSION

Rosiglitazone therapy of NASH is associated with increased crystalline inclusions in hepatocyte mitochondria. Whether these are adaptive or pathological remains unknown, and further studies are warranted to assess hepatic mitochondrial function during thiazolidinedione therapy for NASH.

The zonal distribution of megamitochondria with crystalline inclusions in nonalcoholic steatohepatitis

Megamitochondria with crystalline inclusions (MMC) have been previously described in nonalcoholic fatty liver; however, their distribution within hepatic zones is unknown. We sought to determine this distribution from the core liver biopsy specimens of 31 patients: 8 males and 23 females, age range 21 to 72 years. Twenty-nine showed evidence of nonalcoholic steatohepatitis (NASH) on biopsy with steatosis, inflammation, varying degree of fibrosis, ballooned hepatocytes, and Mallory hyaline, and two patients had cryptogenic cirrhosis thought to represent "burned out" NASH. Identified by transmission electron microscopy, the abundance of MMC was compared between low-stage (fibrosis stages 1 and 2) and high-stage (fibrosis stages 3 and 4) groups and between zones with or without difference in fibrosis stage. Regardless of stage, the MMC were distributed equally in all zones and were abundant similarly in low- and high-stage groups. This abundance did not correlate with the degree of oxidative stress (4-hydroxynonenal staining) or with the abundance of ballooned hepatocytes. Consistent with age as a risk factor for more severe disease, the median age for the low-stage group was significantly lower than that of the high-stage group (P =.003). In conclusion, in NASH, the MMC seem to be distributed randomly among zones and without variation in abundance, regardless of the fibrosis stage. The exact function of these structures remains to be defined. In this study, their presence did not seem to correlate with the light microscopic injury pattern represented by ballooned hepatocytes or degree of oxidative stress defined by immunostaining for 4-hydroxynonenal.

A pilot study of a thiazolidinedione, troglitazone, in nonalcoholic steatohepatitis

OBJECTIVES

Troglitazone is a thiazolidinedione and peroxisome proliferator-activated receptor gamma (PPARgamma) ligand used to treat diabetes mellitus type II. Because hyperinsulinemia may be a factor in nonalcoholic steatohepatitis (NASH), we postulated that troglitazone could have beneficial effects in this disorder. Our study was initiated before reports of idiosyncratic hepatitis induced by this agent and was completed before its recent withdrawal from the market.

METHODS

We studied 10 female patients (age 44 +/- 16) with histological NASH. All but two were obese (mean body mass index, BMI = 38 +/- 6). One had type 2 diabetes, and three had well-compensated cirrhosis with NASH. Troglitazone was given at a dose of 400 mg/day for < or = 6 months. Responders (defined as normal ALT at the end of treatment) were rebiopsied. Paired specimens were compared in blinded fashion. Mitochondria were quantitated using ultrathin electron microscopy.

RESULTS

Seven of ten patients responded with normal ALT at the end of treatment. One of three nonresponders initially normalized ALT but returned to pretreatment level at 3 months. In this patient, therapy was stopped, and the ALT has remained at the baseline level with no other clinical or laboratory findings. In the responders, ALT fell from 87 +/- 38 before to 39 +/- 9 at the end of treatment (p = 0.01), and AST decreased from 77 +/- 23 to 30 +/- 8 (p = 0.002). Biopsy comparisons before and after therapy showed persistent steatohepatitis in all cases, although four of seven showed a one-point improvement in the necroinflammatory grade. Electron microscopy revealed elongation of the mitochondria after therapy.

CONCLUSIONS

Normal ALT was seen in 70% of NASH patients at the end of treatment, but this biochemical response was associated with only mild histological improvement, and all follow-up biopsies had evidence of NASH. Normalization of the liver enzymes in patients with NASH who are treated with thiazolidinediones should be viewed with reservation. Follow-up biopsy is essential to evaluate the efficacy of these agents, which, at the histological level, appears to be relatively modest.

Electrical, morphological, and ultrastructural remodeling and reverse remodeling in a canine model of chronic atrial fibrillation

BACKGROUND

In patients with recurrent persistent atrial fibrillation (AF), vulnerability to AF persists indefinitely despite presumed completion of reverse electrical remodeling within days of return to normal sinus rhythm. Atrial electrical and anatomic remodeling and reverse remodeling were studied in a canine model of chronic AF.

METHODS AND RESULTS

Chronic AF was induced in 8 dogs by creating moderate mitral regurgitation and rapidly pacing the right atrium at 640 bpm for >8 weeks. Measurements performed at baseline, after establishment of chronic AF, and then at 4 hours and again at 7 to 14 days after cardioversion to sinus rhythm included atrial effective refractory periods, AF cycle lengths, left atrial dimensions, premature atrial contraction (PAC) frequency, and atrial vulnerability to atrial extrastimuli. After establishing chronic AF, atrial effective refractory period shortening, increases in spontaneous PAC frequency, increases in left atrial size with loss of contractility, and multiple ultrastructural abnormalities were demonstrated. Complete reverse electrical remodeling and decreases in PACs were observed after 7 to 14 days of sinus rhythm, but there was no resolution of anatomic and ultrastructural abnormalities. Occurrence of spontaneous AF paralleled PAC frequency, but vulnerability to AF induction persisted (75% immediately after conversion versus 63% at 4 hours and 50% at 7 to 14 days) despite reverse electrical remodeling.

CONCLUSIONS

After conversion from chronic AF to sinus rhythm in this canine model, electrical remodeling occurs rapidly. However, gross and ultrastructural anatomic changes persist, as does vulnerability to induced AF. Vulnerability to AF initiation 7 to 14 days after cardioversion is more dependent on persisting structural abnormalities than on electrophysiological abnormalities.

Ultrastructural changes in rabbit ciliary body after extraocular mitomycin C

PURPOSE

To study the ultrastructural changes in ciliary body epithelium of the rabbit eye after subconjunctival injections of mitomycin C.

METHODS

One eye of six New Zealand white rabbits was given a subconjunctival injection at the 12-o'clock position with 0.005, 0.02, 0.08, 0.1, 0.12, or 0.16 mg mitomycin C. The fellow eye was given a subconjunctival injection of balanced salt solution. Two weeks after treatment, the eyes were enucleated, and the ciliary body was exposed and submerged in fresh 4% paraformaldehyde/2% glutaraldehyde in 0.1 M phosphate buffer, pH 7.4, at 4 degrees C. Electron microscopy of the ciliary body was performed at two sites: the injection site (12-o'clock position) and 180 degrees away (6-o'clock position).

RESULTS

At dosages of 0.1 mg and higher, ciliary body epithelial cells beneath the injection site were thinned. There were vacuoles and expansion of intracellular and intercellular spaces. Plasma membrane infoldings were disrupted, and the apical membrane was thinned. Mitochondria and nuclei were normal. Ciliary body epithelium at 6-o'clock position showed only mild architectural distortion of the plasma membrane infoldings. Eyes that received lower doses of mitomycin C (0.005 mg, 0.02 mg, and 0.08 mg) and balanced salt solution showed normal ciliary body epithelium at the injection site and 180 degrees away.

CONCLUSIONS

Subconjunctival injection of mitomycin C in the rabbit produces dose-dependent localized ultrastructural changes of the ciliary body epithelium.

Ultrastructural observations in the myocardium beyond the region of acute coagulation necrosis following radiofrequency catheter ablation

INTRODUCTION

We hypothesized that myocardial injury following radiofrequency (RF) catheter ablation may extend beyond the region of acute coagulation necrosis as defined by histochemical staining.

METHODS AND RESULTS

Five RF lesions were created in vivo in the left ventricle of two dogs using a 4-mm tipped ablation electrode in which RF power was adjusted to maintain an electrode-tissue interface temperature of 85 degrees C for 60 seconds. The lesions were bisected; one half of the lesions were stained with nitroblue tetrazolium (NBT) and the other half processed for electron microscopy. Three zones of interest were identified extending 0-3 mm, 3-6 mm, and > 6 mm from the visible pathologic lesion border. The degree of ultrastructural injury to the myocardium was scored for each zone. Electron microscopy demonstrated the presence of significant abnormalities of the plasma membrane, mitochondria, sarcomeres, sarcoplasmic reticulum, and gap junctions of myocytes, as well as damage to the microvasculature extending up to 6 mm beyond the pathologic lesion edge. The plasma membrane and gap junctions of myocytes and the microvasculature appeared particularly sensitive to thermal injury, whereas the intercalated discs were relatively thermally resistant.

CONCLUSION

RF catheter ablation results in ultrastructural damage to the myocardium extending up to 6 mm beyond the acute pathologic RF lesion border as defined by NBT histochemical staining.

Expression of parathyroid hormone-related protein and its receptor in human umbilical cord: evidence for a paracrine system involving umbilical vessels

OBJECTIVE

Our purpose was to study the expression and localization of parathyroid hormone-related protein and expression of the parathyroid hormone/parathyroid hormone-related protein receptor in human umbilical cord.

STUDY DESIGN

The expression and localization of parathyroid hormone-related protein and expression of the parathyroid hormone/parathyroid hormone-related protein receptor were studied in isolated tissues from the human umbilical cord by Northern analysis, reverse-transcriptase polymerase chain reaction, Southern gel analysis, and immunolocalization procedures at the light and electron microscopic levels.

RESULTS

Parathyroid hormone-related protein was abundantly expressed in the umbilical cord. Immunohistochemical and immunocytochemical techniques confirmed hormone localization in the amnion epithelial layer and in vascular smooth muscle and endothelial cells in vessels from the umbilical cord and placental chorionic plate. Multiplex reverse-transcriptase polymerase chain reaction identified expression of receptor messenger ribonucleic acid in vessels of the umbilical cord; this finding was verified by means of Southern gel analysis of the products of the reverse-transcriptase polymerase chain reaction.

CONCLUSION

A parathyroid hormone-related protein paracrine system appears to exist in human umbilical cord. We suggest that it may be involved in the control of fetal placental circulation.

Quantitative immunohistochemistry: a comparison of microdensitometric analysis of unlabeled antibody peroxidase-antiperoxidase staining and of microfluorometric analysis of indirect fluorescent antibody staining for nicotinamide adenosine dinucleotide phosphate (NADPH)-cytochrome c (P-450) reductase in rat liver

The intralobular distribution of nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome c (P-450) reductase (NADPH:ferricytochrome oxidoreductase, EC 1.6.2.4) in rat liver has been investigated by means of two quantitative immunohistochemical techniques: microdensitometric quantitation of unlabeled antibody peroxidase-antiperoxidase staining and microfluorometric analysis of indirect fluorescent antibody staining. Utilizing sheep antiserum elicited against NADPH-cytochrome c (P-450) reductase that had been isolated and purified to apparent homogeneity from rat liver microsomes, the reductase was detected within hepatocytes throughout the liver. However, differences in the intensity of staining of hepatocytes within different regions of the liver lobule were readily apparent after completion of both immunohistochemical staining procedures. These visual findings were verified by microdensitometric and microfluorometric analyses of immunohistochemical staining, both of which revealed that approximately the same degree of staining for NADPH-cytochrome c (P-450) reductase was produced within the centrilobular and midzonal regions of the liver lobule, whereas periportal hepatocytes were stained with significantly less intensity. These results demonstrate that the application of either microdensitometry in conjunction with unlabeled antibody peroxidase-antiperoxidase staining or microfluorometry after indirect fluorescent antibody staining can be used to quantitatively determine the intratissue distributions of antigens.

Immunohistochemical localization of glutathione S-transferases in livers of untreated rats

Sheep antibodies raised against three isoenzymes of glutathione S-transferase (EC 2.5.1.18), transferases B, C, and E, which were isolated and purified to apparent homogeneity from rat liver, have been employed to localize these enzymes at the light microscopic level within livers of untreated rats. Using these antibodies in an unlabeled antibody peroxidase-antiperoxidase staining technique, each glutathione S-transferase was detected immunohistochemically within parenchymal cells throughout the liver lobule. In addition, immunohistochemical staining for transferases C and E, but not for transferase B, was observed within bile duct epithelium. While all parenchymal cells were stained with each glutathione S-transferase antibody, the patterns of immunohistochemical staining intensity observed across the liver lobule with the three anti-transferases were not uniform: parenchymal cells within the centrilobular region were more intensely stained for each lobular region were more intensely stained for each isoenzyme than were those within the midzonal and periportal regions of the lobule. The results of this immunohistochemical study thus demonstrate that glutathione S-transferases are not distributed uniformly throughout the liver lobule and that each transferase is present in the greatest concentration within the centrilobular region of the lobule.

Immunohistochemical studies on electron transport proteins associated with cytochromes P-450 in steroidogenic tissues. II. Microsomal NADPH-cytochrome c reductase in the rat adrenal

NADPH-cytochrome c reductase (NADPH : ferricytochrome oxido-reductase, EC 1.6.2.4), the flavoprotein which mediates the NADPH-dependent reduction of cytochromes P-450 in adrenocortical microsomes, has been localized immunohistochemically at the light microscopic level in rat adrenal glands. Localization was achieved through the use of sheep antiserum produced against purified, trypsin-solubilized rat hepatic microsomal NADPH-cytochrome c reductase in both an unlabeled antibody peroxidase-antiperoxidase technique and an indirect fluorescent antibody method. The sheep antibody to rat hepatic microsomal NADPH-cytochrome c reductase concomitantly inhibited the NADPH-cytochrome c reductase and progesterone 21-hydroxylase activities catalyzed by isolated rat adrenal microsomes. When sections of rat adrenal glands were exposed to the reductase antiserum in both immunohistochemical procedures, positive staining for NADPH-cytochrome c reductase was observed in parenchymal cells of the three cortical zones but not in medullary chromaffin cells. The intensity of staining, however, was found to differ among the three cortical zones, with the most intense staining being found in the zona fasciculata and the least in the zona glomerulosa. The intensity of staining was also found to differ among cells within the zona fasciculata. These immunohistochemical observations demonstrate that microsomal NADPH-cytochrome c reductase is not distributed uniformly throughout the rat adrenal cortex.

SIF cells, cyclic AMP responses, and catecholamines of the guinea pig superior cervical ganglion

The superior cervical ganglion (SCG) of the guinea pig has been investigated by a multidisciplinary approach. Dopamine (50 micron) produced no increase in cyclic AMP levels above control values of 27.9 pmole/mg protein, but 50 micron isoproterenol produced cyclic AMP levels of 210 pmole/mg protein, indicating the existence of a beta-adrenergic receptor-adenylate cyclase complex. The SIF cells were studied by fluorescence histochemistry, which indicated that two morphological types were present. A few Type I cells of the guinea pig SCG were solitary, but most were present in clusters containing many Type II cells. Immunohistochemical localization of antibodies to dopamine-beta-hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT) demonstrated that types of SIF cell localize antibodies to DBH but not PNMT, providing strong evidence that norepinephrine is the neurotransmitter for all the SIF cells of the guinea pig SCG. Determination of the ratio of norepinephrine to dopamine confirmed that no other dopamine pools exist in the guinea pig SCG.

A technique for the immunohistochemical localization of prostaglandin E

Prostaglandin E (PGE) has been localized via the unlabeled antibody technique in freeze-dried and ethanol-fixed cryostat sections. Discrete perivascular and stromal localization was present in the uterus prepared by the method presented, but not in classically fixed specimens. Absorption of the anti-PGE by addition of free PGE was ineffective; whereas, removal of PGE-reactive antibodies from the anti-serum was effectively accomplished with an Affigel-101-PGE immunoadsorbant column.

A modification of the unlabeled antibody enzyme method using heterologous antisera for the light microscopic and ultrastructural localization of insulin, glucagon and growth hormone

The requirement of using homologous antisera (primary antiserum and peroxidase-antiperoxidase (PAP) complex raised in the same species) in the unlabeled antibody enzyme method has been investigated at the light and electron microscopic level using the localization of insulin, glucagon and growth hormone as model systems. Optimum immunocytochemical staining for all three antigens was observed when sheep or goat antirabbit gamma-globulin (S-ARgammaG or G-ARgammaG) were used to couple rabbit peroxidase-antiperoxidase complex with either guinea pig antisera to insulin (GP-AIS) or glucagon (GP-AGS), or monkey antisera to rat growth hormone (M-ARGH). The cross-reactivity between S-ARgammaG or G-ARgammaG and immunoglobulins in these primary antisera were substantiated by immunoelectrophoresis and radioimmunoassay. S-ARgammaG was shown to produce precipitation arcs with GP-AIS and M-ARGH that were similar to those seen when the latter were reacted with rabbit antiguinea pig gamma-globulin antiserum and goat antimonkey gamma-globulin antiserum, respectively. Radioimmunoassay results revealed that immunoprecipitation of 6-10% as compared to homologous antisera controls yielded excellent staining localization when S-ARgammaG was used for immunocytochemistry. Thus, heterologous antisera (primary antiserum and PAP complex raised in different species) may be used in the unlabeled antibody enzyme method as long as the coupling antiserum shows cross-reactivity with immunoglobulins of the primary antiserum and the PAP complex.