1H-NMR spectroscopy as a means of monitoring nephrotoxicity as exemplified by studies with cephaloridine.

1. Male albino rats were dosed intravenously with either 0.9% saline or cephaloridine in saline at doses of 650, 750 or 950 mg kg-1 d-1 for 7 d. 2. Urine analysis on day 3, after two doses of cephaloridine showed dose-related increases in glucose, total protein, N-acetyl beta-D-glucosaminidase, gamma-glutamyltranspeptidase, alkaline phosphatase and lactate dehydrogenase. 1H-NMR spectroscopy showed corresponding disturbed profiles of products of intermediary metabolism indicative of a disruption of renal function. 3. By day 6, after five doses of cephaloridine, analysis by both 1H-NMR and conventional methods showed that all indices had returned to normal. 1H-NMR was demonstrated to provide useful complementary information to conventional techniques on the time course of the onset of the nephrotoxicity and the recovery phase, and was at least as sensitive as conventional urine analysis.

Safety evaluation of meropenem in animals: studies on the kidney.

The effect of meropenem on animal kidneys has been assessed in rats (5 of each sex/group), rabbits (3 of each sex/group) and monkeys (3 of each sex/group) in comparative iv studies with ceftazidime, cefotaxime, cephaloridine and imipenem (without cilastatin). Diarrhoea occurred in rabbits and monkeys dosed with imipenem or meropenem. Emesis occurred only after the administration of imipenem to monkeys. After 14 days administration to rats evidence of nephrotoxicity was seen only in males dosed with cephaloridine (850 mg/kg); no changes were seen with ceftazidime, cefotaxime or meropenem (all at 1000 mg/kg). Four days after a single dose to rabbits renal tubular necrosis was seen in all animals receiving imipenem (150 mg/kg) and cephaloridine (250 mg/kg). Minimal histopathological changes to the kidneys were seen with cefotaxime, ceftazidime and meropenem (all at 400 mg/kg). After seven days' administration to cynomolgus monkeys imipenem (180 mg/kg) caused moderate to severe tubular necrosis. No tubular damage was seen with meropenem at 180 mg/kg or with cefotaxime or ceftazidime (both at 500 mg/kg). At 500 mg/kg meropenem caused mild tubular regeneration and/or fat accumulation in 3/6 animals, with mild tubular necrosis in one of these. The data from these three species indicate that meropenem has a low nephrotoxic potential in these animal models.

A survey of the pathology of marmosets (Callithrix jacchus) derived from a marmoset breeding unit.

The results of a survey of the major pathological conditions encountered in an established breeding colony of common cotton-eared marmosets (Callithrix jacchus) is presented. 265 home-bred and 70 imported wild-caught marmosets were examined. A Heinz body haemolytic anaemia and skeletal muscle myopathy were the most common pathological findings and were considered to be a result of a complex nutritional deficiency involving vitamin E, selenium and protein. Inflammatory disease of the intestinal tract was also a major feature. Chronic colitis was particularly common in older marmosets. Pneumonia, otitis media, meningitis and brain abscesses were important pathological findings in home-bred marmosets and were commonly associated with bacterial infections, particularly Bordetella bronchiseptica and Klebsiella species. Trichospirura leptostoma within pancreatic ducts of wild-caught marmosets was the only significant parasitic disease encountered. Mycotic infections of the upper alimentary tract with Candida species were occasional findings in debilitated animals. No pathological features suggesting viral diseases were found.

2-hydroxystilbamidine isethionate: a new fluorochrome for use in general pathology. II. The selective demonstration of fungi.

Paraffin sections of kidney, lung and oesophagus containing Aspergillus sp., Cryptococcus neoformans and Candida sp. were taken from human post mortem material and from the marmoset Callithrix jacchus. Sections were stained for 1-5 min in buffered 2-hydroxystilbamidine isethionate containing sodium metabisulphite after pre-oxidation in 1 per cent aqueous periodic acid. Sections were dehydrated, cleared and mounted in Polymount. When excited with UV light hyphae and fungal bodies fluoresced white contrasting sharply with yellow nuclear fluorescence. With blue light nuclei and fungi fluoresced yellow. Staining with the fluorochrome was pH dependent and behaved as a Schiff type reagent indicative of its probable behaviour as a basic dye. The method was simple, rapid and provided permanent fluorescent preparations which over a number of years did not fade with routine storage.

2-hydroxystilbamidine isethionate: a new fluorochrome for use in general pathology. I. The selective staining of DNA, mucosubstances and elastic fibres.

2 mg of 2-Hydroxystilbamidine isethionate when dissolved in 50 ml 0.1 M citric acid produced nuclear fluorescence in paraffin sections. Pre-hydrolysis in 5N HCl at room temperature increased selectivity of nuclear fluorescence. The addition of 100-200 mg sodium metabisulphite to the fluorochrome solution and preoxidation in periodic acid produced selective fluorescence of mucosubstances. Pre-oxidation with potassium permanganate induced selective fluorescence of elastic fibres. Yellow nuclear fluorescence contrasted clearly with blue/white fluorescence of mucosubstances and elastic fibres when excited with UV light. Unwanted nuclear fluorescence was quenched with 5% iron alum solution. Mast cells selectively fluoresced in acid alcoholic solutions of the fluorochrome. The procedures described were simple and rapid and produced permanent fluorescent preparations. The metachromatic fluorescence of nuclei in contrast to that of mucosubstances and elastic fibres eliminated the need for counterstaining.

A morphological and histochemical study of a drug-induced enteropathy in the Alderley Park rat.

Two experiments were devised to produce an experimental enteropathy. In Experiment I, male Alderley Park rats were dosed daily by gavage with 20 mg/kg and 60 mg/kg of an antibacterial compound ICI 17,363. Animals were killed sequentially at daily intervals up to and including Day 9 to study the development of the enteropathy. In Experiment II rats were dosed daily with 60 mg/kg of the same compound. All animals were killed on Day 5 owing to a rapid development of the enteropathic condition. The duodenum was examined histologically and histochemically. Duodenal changes included vacuolation of columnar epithelial cells and villus stunting. There were marked reductions in mitotic activity in the crypt epithelial cells from Day 7 onwards (Experiment I) and almost total loss of hydrolytic and oxidative enzyme activity. In Experiment II the changes were more severe and haemorrhage and erosion of the duodenal mucosa were observed. The development of the enteropathic lesion appears to be due largely to the antimitotic effect of the compound, although a direct toxic effect upon the intestinal mucosa cannot be ruled out.

The use of a basic dye (azure A or toluidine blue) plus a cationic surfactant for selective staining of RNA: a technical and mechanistic study.

Selective purple staining of RNA-rich structures such as basophilic cytoplasms of exocrine pancreas and plasma cells, Nissl substance, and nucleoli was achieved by treating tissue sections as follows. Stain dewaxed sections for 1/2 hour in a dyebath containing 0.1% w/v axure A or toluidine blue and 1% cationic surfactant (Hyamine 2389, a 50% w/v aqueous solution of diisobutylphenoxyethoxyethyldimethylbenzylammonium chloride; or benzyldimethylammonium chloride, or cetylpyridinium bromide, or cetyltrimethylammonium bromide) buffered to pH 7 with phosphate. Rinse in water, blot, air dry and mount in synthetic resin. Intense purple staining of RNA-rich regions occurred after fixation in neutral formalin or in Carnoy's or Gendre's fluids, though satisfactory results were also found after fixation in acetone or alcohol. Chromatin generally stained a very pale azure after all fixations, though occasionally nuclei were unstained (Gendre's or Zenker's fluids). Subjecting tissue sections to acid hydrolysis or to digestion by RNAase eliminated or reduced the purple staining, but left the azure staining of nuclei unaffected. Satisfactory staining of RNA-rich structures was not critically dependent on the precise concentrations of dye, surfactant or inorganic salts in the dyebath, nor on pH, staining time or chemical nature of the surfactant. The staining patterns can be rationalized with a tissue model that considers both surface charge and permeability factors, since present in the dyebath are small dye cations and large cationic surfactant micelles. As micelles and dye will both quickly penetrate basophilic structures considered to be porous, such as chromatin, competition will then greatly reduce staining of such substrates. But the large micelles will only slowly penetrate regions considered to be more impermeable, such as basophilic cytoplasms, so consequently small fast moving dye ions may enter and stain without competition.

Psoriasis--changes in surface microtopography.

Easily prepared adhesive slides have been used to obtain surface-layer biopsy specimens from psoriasis and other scaly dermatoses that occur on the limbs. Psoriasis obliterates the normal skin pattern, but the change is not specific. However, as psoriasis undergoes spontaneous or treatment-induced resolution, the skin surface pattern reappears and develops through a series of pattern changes that closely correlate with the clinical appearance of the lesion. This method may be used to monitor changes in the stratum corneum.