Characterisation of inorganic microparticles in pigment cells of human gut associated lymphoid tissue.

Macrophages at the base of human gut associated lymphoid tissue (GALT), become loaded early in life with dark granular pigment that is rich in aluminium, silicon, and titanium. The molecular characteristics, intracellular distribution, and source of this pigment is described. Laser scanning and electron microscopy showed that pigmented macrophages were often closely related to collagen fibres and plasma cells in GALT of both small and large intestine and contained numerous phagolysosomes, previously described as granules, that are rich in electron dense submicron sized particles. Morphological assessment, x ray microanalysis, and image electron energy loss spectroscopy showed three distinct types of microparticle: type I - spheres of titanium dioxide, 100-200 nm diameter, characterised as the synthetic food-additive polymorph anatase; type II - aluminosilicates, < 100-400 nm in length, generally of flaky appearance, often with adsorbed surface iron, and mostly characteristic of the natural clay mineral kaolinite; and type III - mixed environmental silicates without aluminium, 100-700 nm in length and of variable morphology. Thus, this cellular pigment that is partly derived from food additives and partly from the environment is composed of inert inorganic microparticles and loaded into phagolysosomes of macrophages within the GALT of all human subjects. These observations suggest that the pathogenicity of this pigment should be further investigated since, in susceptible individuals, the same intracellular distribution of these three types of submicron particle causes chronic latent granulomatous inflammation.

Effect of eradication of Helicobacter pylori on gastric epithelial cell proliferation.

BACKGROUND: Helicobacter pylori is associated with B-type gastritis, duodenal ulcer disease, and possibly gastric carcinoma. The object of this study was to assess the effect of eradication of H. pylori infection on gastric epithelial cell proliferation. METHODS: Gastric epithelial cell proliferation was assessed in 22 H. pylori-positive duodenal ulcer patients before and 6 weeks after 'triple therapy' with bismuth, tetracycline and metronidazole. Cell proliferation was studied either by immunostaining for the proliferating cell nuclear antigen (PCNA) or by a microdissection technique. RESULTS: Eradication was successful in 10 of the 22 H. pylori-positive patients. Treatment with 'triple therapy' resulted in a significant fall in the rate of gastric epithelial cell proliferation; this effect was seen in both the gastric body and antrum. There was a significant correlation between the number of PCNA-labelled cells and the histological grade of activity (neutrophil inflammation) (r = 0.49, P = 0.02); the same correlation was found for the number of mitoses per gland (r = 0.5, P = 0.02). There was no significant difference in the treatment effect for eradicated or non-eradicated patients or either the body or antrum. Six patients, who had at least one antral biopsy that showed evidence of focal intestinal metaplasia, had a higher rate of cell proliferation. CONCLUSIONS: The reduction in epithelial cell proliferation in the body and antrum after triple therapy is independent of successful eradication of H. pylori, and it may be due to an anti-inflammatory effect of triple therapy.

A vascular hypersensitivity model of acute multifocal gastrointestinal infarction.

We have investigated the hypothesis that submucosal vasculitis may account for the patchy transmural inflammation observed in Crohn's disease. Test ferrets (N = 11) were sensitized to human albumin. Five days after the last sensitization injection, human albumin microspheres (15-150 microns diameter) were injected intraarterially into the mesenteric circulation of a defined loop of mid-gut. Six control ferrets showed no histological abnormality at either 48 hr or two weeks after intraarterial injection. At 48 hr, five of six presensitized ferrets demonstrated submucosal vasculitis with fibrinoid necrosis. In two cases there was transmural inflammation and mucosal ulceration. A further five presensitized ferrets received weekly subcutaneous human albumin injections following the mesenteric intraarterial injection of albumin microspheres: after two weeks one animal demonstrated mild perivascular inflammatory changes and another demonstrated vasculitis. One of the two animals with transmural inflammation and mucosal ulceration at 48 hr, and the animal with vasculitis at two weeks, had precipitating antibodies to human serum albumin. This model demonstrates that an immune-mediated submucosal vasculitis can sometimes result in discontinuous transmural inflammation of the intestinal wall.

Audit of endoscopic surveillance biopsy specimens in HIV positive patients with gastrointestinal symptoms.

An audit of upper gastrointestinal endoscopy in HIV infected patients with gastrointestinal symptoms assessed the frequency of disease detected by endoscopy and routine laboratory analysis of surveillance biopsy specimens. Sixty nine consecutive endoscopies were performed in 59 HIV infected patients. Endoscopic biopsy specimens were taken from the lower oesophagus, gastric antrum, and third part of the duodenum for virology, histopathology, parasitology, bacteriology, and mycobacterial culture. Endoscopic appearances detected disease in 25/59 (42.4%) patients (oesophageal candida, 14; oesophageal ulcer, 3; Kaposi's sarcoma, 4; others, 4), but only 4/43 (9.3%) specimens showed evidence of disease in the absence of endoscopic abnormality. Virology for cytomegalovirus (detection of early antigenic fluorescent foci and culture) was positive in 6/59 (10.2%) patients, but parasitology and mycobacterial culture were negative in all cases. Histopathology was abnormal in 11/52 (21%) oesophageal biopsy specimens, 13/47 (28%) gastric biopsy specimens, and 4/65 (6%) duodenal biopsy specimens. Abnormal findings were found predominantly in those with advanced HIV disease (CDC Stage IV) (21/33 patients (64%)) compared with those with early HIV disease (CDC Stage II) (5/26 (19%)). In conclusion, upper gastrointestinal endoscopy detects macroscopic disease in AIDS patients and those with low CD4 counts, but routine surveillance biopsy specimens of apparently normal bowel in early HIV disease (or where CD4 counts are greater than 0.2 x 10(9)/1) are of little value.

Early mucosal changes in Crohn's disease.

Aphthoid ulceration has been regarded as an early macroscopic feature of Crohn's disease, yet the cause of this mucosal lesion is unknown. Examination of areas of apparently normal and non-inflamed bowel in Crohn's disease has allowed the identification of mucosal changes which occur before macroscopic and microscopic ulceration. Thirty five resection specimens from patients with Crohn's disease were compared with 12 specimens from patients with ulcerative colitis and 13 controls. Specimens were fixed either by immersion in formalin in the routine way or by perfusion fixation with formalin at mean arterial pressure. Immunostaining for macrophages, vessel wall, and blood constituents allowed identification of small mucosal capillaries which were not apparent otherwise. In Crohn's disease damage and rupture of these small capillaries occurred before infiltration of the lamina propria by inflammatory cells. Loss of the overlying epithelium seemed to follow this vascular damage.

Pulmonary platelet aggregates: possible cause of sudden peroperative death in adults undergoing liver transplantation.

AIMS: To determine if massive pulmonary platelet thromboembolism is a common cause of peroperative death following liver transplantation; and to compare the incidence of this event with patients dying after non-transplantation procedures. METHODS: Necropsy tissues from all patients dying within 10 days of operation during the past three and a half years were studied (six liver transplantations and 13 unrelated operations). Haematoxylin and eosin stained sections of all tissues were examined. Additional sections of lung tissue were immunostained for constituents of thrombus (fibrin and platelets). RESULTS: At necropsy the lungs from all six liver transplant recipients were heavy with a rubbery texture and little oedema fluid. Those from non-transplantation patients appeared normal or very oedematous. Microscopic examination showed that there were numerous platelet aggregates occluding pulmonary capillaries in all six transplant recipients, but in only three of the non-transplant patients. These thrombi were numerous in patients dying during surgery and the number was underestimated in routine sections because of the surrounding capillary congestion. Detection was improved by immunostaining for platelets with factor XIIIA and platelet glyco-protein IIIa. CONCLUSIONS: Massive platelet thromboembolism is a likely cause of death in patients dying unexpectedly following recent liver transplantation. Non-transplantation patients dying during surgery who show similar appearances usually have conditions known to have a high risk of thrombosis or embolism (cement hypotension syndrome and disseminated intravascular coagulation). The cause of this extensive platelet activation in liver transplant recipients is uncertain and may be multifactorial. The unusual rubbery consistency of the lungs on macroscopic examination could alert the pathologist to the underlying condition. Immunostaining for platelets improves the detection microscopically.

Factor XIIIA subunit and Crohn's disease.

Factor XIIIA is the active subunit of plasma factor XIII that is responsible for cross linking fibrin into a stable clot. Sixteen patients with Crohn's disease were studied prospectively from relapse (Crohn's disease activity index > 150) into remission. Plasma factor XIIIA concentrations were significantly lower in active disease (median 63 (95% CI 46-72) U/dl) than remission (median 90 (95% CI 60-112) U/dl; p = 0.002). Plasma factor XIIIA concentrations correlated positively with the activity index (p = 0.005) and platelet count (p = 0.003), and negatively with serum albumin (p = 0.006). In five patients with persistent aggressive disease, the factor XIIIA concentration remained below the lower range of normal despite apparent clinical improvement in response to medical treatment. Tissues from three patients who underwent surgical resection during the study were immunostained for factor XIIIA. Gut mucosal and submucosal macrophages stained strongly for factor XIIIA. In one patient, capillary thrombi near superficial mucosal erosions immunostained for factor XIIIA in macroscopically normal mucosa. Similar changes were identified in more severely inflamed sections of intestine from the other two patients. The demonstration of significantly low plasma factor XIIIA concentrations in active Crohn's disease, and the immunostaining of factor XIIIA in capillary thrombi in the bowel wall, suggest that activation of coagulation may be involved in the pathogenesis of Crohn's disease. The plasma factor XIIIA concentration may prove a useful laboratory marker of disease activity.

Mucosal capillary thrombi in rectal biopsies.

We studied the initial rectal biopsy from 46 patients in whom subsequent follow-up established the diagnosis of either self-limited colitis or inflammatory bowel disease. An additional 12 non-inflamed rectal biopsies were also studied. There was between 2 and 8 years of follow-up in each of these cases. Staining for fibrin (MSB, fibrinogen), platelets (factor XIIIA, Y2/51), and capillary basement membrane (reticulin, collagen 4) was performed to identify thrombotic material within capillaries. Mucosal capillary thrombi were best identified by staining for factor XIIIA; thrombi were observed in 8/13 cases of ulcerative colitis, 4/10 cases of Crohn's disease, 1/3 cases of unspecified inflammatory bowel disease and 5/20 cases of self-limited colitis. The presence of capillary thrombi was not related to the severity of inflammation, but none of the control biopsies showed capillary thrombi. Their presence seems of little diagnostic value in distinguishing inflammatory bowel disease from self-limited colitis. The pathogenetic significance of these mucosal capillary thrombi is uncertain.

Immunohistochemical studies on the innervation of human transplanted liver.

The changing pattern of innervation in the human transplanted liver was studied from the day of transplantation to 5 years later. Seven liver biopsies from non-transplant controls, 37 liver biopsies from 22 transplant patients, and one of these biopsied livers removed at retransplantation, were available for the study. Sections were immunostained for protein gene product 9.5 (PGP 9.5), neurone-specific enolase (NSE), S-100 protein, and vasoactive intestinal polypeptide. NSE and PGP 9.5 demonstrated nerves most successfully in our tissues. Staining for most small nerves was reduced by day 5 post-transplantation. Scanty fine nerves could be detected from day 13 to day 241 in occasional biopsies. Consistently identifiable immunostaining of PGP 9.5 and NSE nerve fibres was again apparent in portal areas after this time in all but one case. The findings indicate that in transplanted liver limited reinnervation can eventually take place. This could be due to either proliferation of intrinsic nerves, or regrowth of extrinsic nerves, or both.

A ferret model of acute multifocal gastrointestinal infarction.

Based on the demonstration of mural granulomatous vasculitis in Crohn's disease, it was hypothesized that this vasculitis may account for the discontinuous pattern of lesions in this condition. Accordingly, the present study investigated the histological changes produced by interruption of the submucosal and mucosal microcirculation in the ferret midgut. Two techniques were used. First, up to 30 adjacent vasa recta were ligated using microsurgical techniques; this produced no evidence of ischemic damage. Second, interruption of the submucosal collateral plexus by the intra-arterial injection of styrene microspheres (27-, 50-, or 90-microns diameter) produced acute intestinal mucosal damage. A combination of 27- and 90-microns spheres resulted in focal mucosal inflammation, necrosis, and ulceration. "Summit" lesions with normal adjacent mucosa were observed 48 hours after embolization, with evidence of regeneration of the mucosa overlying the occluded vessels at 72 hours. This model shows that focal gastrointestinal infarction with normal adjacent mucosa can be produced by acute occlusion of submucosal and mucosal arteries.

Neuroendocrine changes in rat stomach during experimental diabetes mellitus.

The effects of 48 days of streptozotocin-induced diabetes mellitus in rats on plasma concentrations of gastrin, somatostatin, pancreatic glucagon, and enteroglucagon have been assessed. In addition, neuroendocrine changes in sections of gastric mucosa were quantified using a computer-assisted morphometric system following immunohistochemical staining with polyclonal antibodies directed against gastrin, PGP 9.5 (a neural protein), and somatostatin. Diabetes resulted in significantly increased fasting plasma concentrations of somatostatin, and entero- and pancreatic glucagon. In contrast, lower plasma gastrin concentrations and decreased antral G-cell density were noted in diabetic rats. Gastric somatostatin and neuronal PGP 9.5 stain densities were unaltered by diabetes. Stomachs of diabetic rats weighed less, but both the jejunum and ileum showed evidence of mucosal hyperplasia. The gastric neuroendocrine atrophy observed in diabetes may be a consequence of elevated plasma somatostatin derived from nongastric sources. The enhanced growth of the intestinal mucosa may be related, directly or indirectly, to raised intraluminal glucose concentration in diabetes.

Granulomatous vasculitis in Crohn's disease.

This study investigated a possible vascular origin for granulomas in Crohn's disease. Twenty-four consecutive resected specimens of small and large intestinal Crohn's disease were preserved by arterial perfusion-fixation with 10% formol saline, at mean arterial pressure (100 mm Hg). Fifteen specimens contained granulomas on routine examination of H&E-stained sections. These 15 specimens were examined in detail using a range of immunohistochemical staining techniques to identify vascular structures and granulomas. A total of 485 granulomas were found, 85% of which were identified as being directly involved in vascular injury. The majority (77%) of granulomas were deep to the mucosa; they were found most frequently in the submucosa (42%). The techniques used in this study enhanced the recognition of granulomatous vasculitis. The results suggest that the majority of granulomas in Crohn's disease form within walls of blood vessels. Vascular localization of granulomatous inflammation suggests that the intestinal microvasculature contains an early element in the pathogenesis of Crohn's disease.

Congestive gastropathy and Helicobacter pylori: an endoscopic and morphometric study.

Congestive gastropathy is a frequent cause of upper gastrointestinal haemorrhage in patients with portal hypertension. The pathogenesis is thought to involve venous congestion with gastric mucosal capillary dilatation. We studied the relation between gastric mucosal capillary dilatation, measured morphometrically, and endoscopic appearances in 74 patients with portal hypertension and 20 control subjects. We also investigated the frequency of gastric colonisation with Helicobacter pylori. Mucosal capillaries in patients were significantly dilated compared with control subjects (p less than 0.001) but the degree of dilatation was not related to the severity of the endoscopic appearances. H pylori was identified in 19 of 74 (26%) patients but was not related to the severity of the endoscopic appearances. These results suggest that other factors in addition to mucosal venous and capillary congestion are important in the pathogenesis of endoscopic congestive gastropathy and that gastric colonisation with H pylori is unlikely to be one of these factors.

'Neuroendocrine' differentiation in primary neoplasms of the liver.

Thirty primary liver neoplasms (16 hepatocellular, nine biliary, and five epithelioid haemangioendotheliomas) were studied for the expression of the general 'neuroendocrine' markers, neurone specific enolase (NSE) and protein gene product 9.5 (PGP 9.5). Grimelius silver staining for neurosecretory granules and immunostaining for S100 protein, HMB-45, vasoactive intestinal polypeptide (VIP), and calcitonin were also performed. Eleven of the 16 hepatocellular carcinomas stained positively for PGP 9.5, four for NSE, six for HMB-45, and two for S100 protein. Seven exhibited granular staining by the Grimelius method; eight showed immunostaining for VIP, and two for calcitonin. Three of the five haemangioendotheliomas demonstrated positive immunostaining for PGP 9.5, and two for NSE; of the nine biliary carcinomas, two showed staining for PGP 9.5 and NSE, and four contained cells staining with the Grimelius technique. Primary neoplasms of liver may show 'neuroendocrine' differentiation and this aspect of their phenotypic expression has to be considered before predicting the site of origin of a tumour in the liver.

QBEnd/10: a new immunostain for the routine diagnosis of Kaposi's sarcoma.

Kaposi's sarcomas are seen more commonly in routine histopathology laboratories since the advent of the more widespread and aggressive variant of the disease associated with HIV infection. Distinguishing nodular lesions from other spindle cell and vascular tumours can sometimes be difficult. Immunohistochemistry has been disappointing as a diagnostic aid, often requiring special fixation or frozen tissue and even then, staining of spindle cells has been variable. We describe the use of the new IgG1 mouse monoclonal antibody raised against human placental endothelial cells, QBEnd/10, on routine formalin-fixed, paraffin-embedded tissue. A retrospective study was performed on 22 Kaposi's sarcomas of skin including patch, plaque, and nodular lesions and compared with 38 other vascular and spindle cell tumours from skin. All sections were stained with haematoxylin and eosin, QBEnd/10, Ulex europaeus agglutinin 1 (UEA-1) and for factor VIII-related antigen (FVIIIRAg). The results demonstrate that spindle cells in lesions from Kaposi's sarcomas, but not other vascular or spindle cell tumours, immunostain clearly with QBEnd/10. Immunostaining for FVIIIRAg shows only weak and irregular positivity of the spindle cells, whilst staining with UEA-1 is consistently negative. We find that immunostaining with QBEnd/10 aids the diagnosis of Kaposi's sarcomas and allows their distinction from other spindle cell neoplasms of skin in routinely processed material.

Immunostaining of antral gastrin cells is quantitatively increased in Heliobacter pylori gastritis.

The amount of gastrin-like immunostaining in gastrin (G) cells of the antral mucosa was quantified using a computer-assisted method of measuring immunoreaction product. Biopsies from 25 patients without Heliobacter-like organisms and 60 patients with varying degrees of infection were immunostained for gastrin. Twenty-five G cells from each patient were measured both subjectively and by image analysis. Gastrin-like immunoreactivity was found to be significantly increased in the presence of Heliobacter-like organisms.

Comparison of the collagenous products synthesized in culture by pig aortic endothelial and smooth-muscle cells. Variability in endothelial-cell cultures.

In contrast with smooth-muscle cells from the same tissue, endothelial cells from pig aorta were found to exhibit in culture considerable variability in the pattern of collagen synthesis between one isolation of cells and the next. Synthesis varied from largely collagen type I to virtually all type III in the absence of type I but with small amounts still of collagens types IV and V, to, in one instance, synthesis basically of only type V. Synthesis usually by these cells of collagen predominantly of the interstitial type (I and III) rather than, as might be expected, that from basement membrane (type IV) was not attributable to the influence of subculture. All four collagen types were deposited in the cell layer to an increased extent in primary compared with secondary cultures of either smooth muscle or endothelial origin. Endothelial cells appeared sometimes to synthesize a large-Mr collagenous entity that might conceivably be related to 'short-chain' collagen. In addition, small-Mr hydroxyproline-containing peptides were detected that might reflect rapid collagen(s) turnover in endothelial cultures.

Analysis of the collagen types synthesized by bovine corneal endothelial cells in culture.

Bovine corneal endothelial cells synthesize in culture predominantly type III collagen, with lesser amounts of types I and V and apparently little if any type IV. This pattern of synthesis is observed in both dividing and post-confluent cultures and irrespective of whether cells are attached to plastic or collagen-coated surface.