Detectable Histological Changes Research Articles

Upregulation of P2X3 receptors in primary afferent pathways involves in colon-to-bladder cross-sensitization in rats.

Background: Clinical investigation indicates a high level of co-morbidity between bladder overactivity and irritable bowel syndrome. The cross-sensitization of afferent pathways has been demonstrated to be the main reason for the cross-organ sensitization, but the underlying mechanism is unclear. Methods: A single dose of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) was applied to induce the colitis rat models by intracolonic administration. All rats were randomly divided into three groups: control, TNBS-3-day, and TNBS-7-day groups. Western blot and immunofluorescent staining were performed to detect the expression of the P2X3 receptor. The spontaneous contractions of the detrusor strip were measured to evaluate the detrusor contractility function. The micturition function was measured by a cystometry experiment. The intercontractile interval (ICI) and maximum bladder pressure (BP) were recorded. Results: The distal colon from colitis showed serious tissue damage or chronic inflammation after TNBS instillation (p < 0.01). However, there were no detectable histological changes in bladder among groups (p > 0.05). TNBS-induced colitis significantly increased P2X3 receptor expression on the myenteric and submucosal plexus of the distal colon and urothelium of the bladder, especially at day 3 post-TNBS (p < 0.05). Meanwhile, the expression of the P2X3 receptor on DRG neurons was increased in TNBS-induced colitis (p < 0.01). The detrusor strip of rats exhibited detrusor overactivity after days 3 and 7 of TNBS administration (p < 0.01), but inhibition of the P2X3 receptor had no effect (p > 0.05). Moreover, the rats with colitis exhibited the micturition pattern of bladder overactivity, manifested by decreased ICI and increased maximum BP (p < 0.05). Interestingly, inhibition of the P2X3 receptor by intrathecal injection of A-317491 alleviated bladder overactivity evoked by TNBS-induced colitis (p < 0.05). Conclusion: The upregulation of the P2X3 receptor in an afferent pathway involved in bladder overactivity evoked by TNBS-induced colonic inflammation, suggesting that the P2X3 receptor antagonist may be an available and novel strategy for the control of bladder overactivity.

Safety Study of Three Concentrations of UniPron Vaginal Contraceptive Microbicidal Gel

Background: UniPron is an antimicrobial and a spermicidal agent that contains citric acid as the active component. This study was designed to evaluate the effects of three different concentrations of UniPron in the baboon (Papio anubis) model. Methods: Twenty sexually mature female baboons were used in this study. Vaginal pH and microflora, blood chemistry, vaginal and cervical histology were evaluated at baseline and after administration of 15 ml of UniPron 0.4, 0.8 and 1.2 gm or placebo twice a week for eight weeks to each randomized treatment group. Results: Baseline vaginal pH was 5.2±0.8. There was no significant difference in the vaginal pH and blood chemistry parameters. The microflora composition was diverse and slight variation in percentage frequency between UniPron concentrations was observed. No detectable histological changes were observed in the vaginal or cervical sections. Conclusion: Repeated application of 15 ml of three UniPron concentrations appeared to be safe when administered intravaginally in the baboon model.

Expression of an insecticidal fern protein in cotton protects against whitefly.

Whitefly (Bemisia tabaci) damages field crops by sucking sap and transmitting viral diseases. None of the insecticidal proteins used in genetically modified (GM) crop plants to date are effective against whitefly. We report the identification of a protein (Tma12) from an edible fern, Tectaria macrodonta (Fee) C. Chr., that is insecticidal to whitefly (median lethal concentration = 1.49 μg/ml in in vitro feeding assays) and interferes with its life cycle at sublethal doses. Transgenic cotton lines that express Tma12 at ∼0.01% of total soluble leaf protein were resistant to whitefly infestation in contained field trials, with no detectable yield penalty. The transgenic cotton lines were also protected from whitefly-borne cotton leaf curl viral disease. Rats fed Tma12 showed no detectable histological or biochemical changes, and this, together with the predicted absence of allergenic domains in Tma12, indicates that Tma12 might be well suited for deployment in GM crops to control whitefly and the viruses it carries.

An Experimental Study of the Potential Biological Effects Associated with 2-D Shear Wave Elastography on the Neonatal Brain

2-D Shear wave elastography (SWE) imaging is widely used in clinical practice, and some researchers have applied this technique in the evaluation of neonatal brains. However, the immediate and long-term impacts of dynamic radiation force exposure on the neonatal central nervous system remain unknown. In this study, we exposed neonatal mice to 2-D SWE scanning for 10 min, 20 min and 30 min under diagnostic mode (mechanical index [MI]: 1.3; thermal index [TI]: 0.5), respectively. For the control group, the neonatal mice were sham irradiated for 30 min with the machine powered off. Their brains were collected and analyzed using histologic staining and western blot analysis at 24 h and 3 mo after the 2-D SWE scanning. The Morris water maze (MWM) test was used to assess learning and memory function of the mice at 3 mo of age. The results indicated that using 2-D SWE in evaluating brains of neonatal mice does not cause detectable histologic changes, nor does it have long-term effects on their learning and memory abilities. However, the PI3 K/AKT/mTOR pathway was disturbed when the 2-D SWE scanning lasted for more than 30 min, and the expression of p-PKCa was suppressed by 10 min or more in 2-D SWE scanning. Although these injuries may be self-repaired as the mice grow, more attention should be paid to the scanning duration when applying 2-D-SWE elastography in the assessment of neonatal brains.

A Comparative Study of Smugel and KY Jelly Vaginal Lubricating Gels

Objective To assess the safety of Smugel compared with KY Jelly vaginal lubricatng gel in baboon (Papio anubis) vagina. Methods Ten sexually mature olive female baboons were used in this study. Vaginal pH, blood chemistry, vaginal flora, vaginal and cervical histology were evaluated at baseline and after administration of 15 ml of either Smugel or KY Jelly gel twice a week for 5 weeks to each randomized treatment group. Results Basal vaginal pH was 5.8 ± 0.8. There was no significant difference in the vaginal pH of Smugel compared with KY Jelly treated animals or baseline data ( P >0.05). Similarly, analysis of blood chemistry parameters revealed no significant differences. The most frequently isolated microorganisms both at baseline and during treatment included Corynebacterium glucuronolyticum, C. renale group, Lactococcus raffinolactis, Leuconostoc lactis, Lactobacillus acidophilus, L. fermentum, L. salivarius, Staphylococcus aureus, S. xyloxus, S. hyicus, Aerococus viridians, Escherichia coli and Candida albicans. No detectable histological changes were observed in the vaginal or cervical sections examined. Conclusion Smugel, compared with KY Jelly did not induce any adverse event that may facilitate transmission of sexual transmitted infection (STI) pathogens including HIV.

Progesterone receptor up-regulation: a diagnostic tool for the illicit use of oestrogens in adult beef cattle

The monitoring of gene regulation via mRNA levels to detect anabolic sex steroid administration in cattle is a novel approach to detecting the illicit treatment of livestock in meat production. A previous study revealed that progesterone receptor (PR) gene expression levels were increased in the bulbourethral glands and prostates of 17β-oestradiol-treated prepubertal calves, suggesting that the PR can be used as a specific molecular biomarker for oestrogen treatment. The aim of this study was to verify the specificity and applicability of the PR to detect the illegal use of 17β-oestradiol in sexually mature beef cattle. Accessory sex glands were sampled from 42 male beef cattle that were divided into six experimental groups, including two control groups, K1 and K2. Group A cattle were treated with 17β-oestradiol (five weekly intramuscular doses of 20 mg), and group B cattle were treated with dexamethasone (40 daily doses of 0.7 mg per os). Group C cattle received an implant of Revalor-200 (200 mg of trenbolone acetate and 20 mg of 17β-oestradiol), and group D cattle received Revalor-200 plus dexamethasone (0.7 mg daily per os). 17β-Oestradiol, either alone or in combination with other steroids, up-regulated the PR gene and protein expression, even in the absence of detectable histological changes in the accessory sex glands, confirming the high sensitivity of PR gene expression as an indirect diagnostic screening tool to detect illicit oestrogen treatment in sexually mature male bovine.

Disruption of GLI3–ZIC3 interaction in the cadmium-induced omphalocele chick model

Administration of heavy metal cadmium (Cd) after 60-h incubation induces omphalocele spectrum in the chick embryo. Although previous studies have shown that the earliest detectable histological changes in the chick Cd model occurs commencing at 4-h post-treatment (4H). However, the molecular mechanism by which Cd acts in the critical period of early embryogenesis still remains unclear. Zic3, a Gli superfamily transcription factor, is expressed in somites and plays an important role in vertebrate development, including somitogenesis and thus ventral body wall formation. Gli3 is also expressed in somites and interacts with Zic3 physically and functionally. It has been reported that Gli3 homozygous double mutants display omphalocele. Zic3 mutant mice have also been known to result in omphalocele phenotype. We designed this study to test the hypothesis that Gli3 and Zic3 gene expression is downregulated during the critical period of very early embryogenesis in the Cd-induced omphalocele in the chick model. After 60-h incubation, chick embryos were exposed to either saline or 50μM cadmium and divided into two groups: control and Cd (n=24 for each group). Real-time reverse transcription polymerase chain reaction was performed to evaluate the relative mRNA expression levels of Gli3 and Zic3 in the Cd-induced omphalocele chick model. Differences between the two groups at each time point were analyzed statistically and the significance was accepted at p<0.05. Immunohistochemistry was also performed to evaluate the expression/distribution of those proteins in chick embryo. The relative mRNA expression level of Gli3 and Zic3 was significantly decreased in the Cd group at 4H when compared with controls (p<0.05). However, there were no significant differences at the other time points. At 4H, immunoreactivity of GLI3 and ZIC3 was also markedly decreased in Cd-treated embryos, whereas strong expression of them was seen in the somite in controls. We provide evidence, for the first time, that Gli3 and Zic3 gene expression is downregulated during the narrow window of very early embryogenesis in Cd chick model. Disruption of Gli3-Zic3 interaction in the critical period for ventral body wall formation may contribute to omphalocele phenotype in Cd chick model.

Disruption of noncanonical Wnt/CA 2+ pathway in the cadmium-induced omphalocele in the chick model

Purpose Cadmium (Cd) has been found to cause ventral body wall defects (VBWDs) in the chick embryo similar to human omphalocele. The earliest detectable histologic changes in Cd-induced VBWD chick model have been observed 4 hours posttreatment. The exact mechanism by which Cd acts in the early embryogenesis remains unclear. Wnt proteins play a key role during embryogenesis, and altered Wnt signaling has been linked to developmental defects. Noncanonical Wnt/Ca 2+ pathway has been implicated in regulating embryogenesis by controlling cell movement and adhesion. Wnt11 can activate protein kinase C (PKC) and calcium/calmodulin-dependent kinase II (CaMKII) in the Wnt/Ca 2+ pathway. We hypothesized that the Wnt11, PKC α, and CaMKII gene expression is downregulated in the Cd-induced VBWD during early embryogenesis. Methods After 60 hours of incubation, chick embryos were harvested 1 hour (1H), 4H, and 8H after treatment of saline or cadmium and divided into 2 groups: control and Cd (n = 8 at each time-point, respectively). Real-time polymerase chain reaction was performed to evaluate the messenger RNA (mRNA) expression of Wnt11, PKC α, and CaMKII in the Cd-induced VBWD chick model. Results The mRNA expression levels of Wnt11, PKC α, and CaMKII were significantly decreased at 1H in Cd group compared to controls ( P < .05). However, there were no significant differences in the other time-points. Conclusion Downregulation of Wnt11, PKC α, and CaMKII gene expression during the narrow window of early embryogenesis may cause VBWD, interfering with cell movement and adhesion, disrupting Wnt/Ca 2+ pathway.

Cutaneous vascular patterns in psoriasis

Microvascular abnormalities are a characteristic feature of psoriasis and play a crucial role in its pathogenesis. Investigational studies have shown that activated keratinocytes in lesional skin undergo an accelerated epidermal cell turnover and are a major source of pro-angiogenic cytokines, like as VEGF, ESAF, PDECGE/TP, TNF-alpha, TGF-alpha and PDGF, suggesting that the epidermis is capable of inducing vascular proliferation. On the other hand, microvascular alterations are essential for the development and persistence of the psoriatic lesions as they provide cellular and tissue nutrition to hyperplastic keratinocytes and promote inflammatory cell migration. Also, dilated and slightly tortuous blood vessels within dermal papillae represent one of the earliest detectable histological changes for all stages of lesional development. Videodermatoscopy is a new non invasive imaging technique able to identify modifications of microvascular architecture in vivo and such evaluation will be useful for the dermatologist both for diagnostic and prognostic evaluation, as well as for post-therapeutic follow-up. In this review, the role of microvascular abnormalities in the pathogenesis of psoriasis as well as the mechanisms underlying vascular changes and their primary therapeutic implications will be reviewed and discussed.

Functional Deficit and Recovery of Developing Sensorimotor Networks following Neonatal Hypoxic-Ischemic Injury in the Rat

Neonatal hypoxia-ischemia (HI) is the most important cause of brain injury in the newborn. Here we studied structural alterations and functional perturbations of developing large-scale sensorimotor cortical networks in a rat model of moderate HI at postnatal day 3 (P3). At the morphological level, HI led to a disorganized barrel pattern in the somatosensory cortex without detectable histological changes in the motor cortex. Functional effects were addressed by means of epicranial mapping of somatosensory-evoked potentials (SEPs) during the postischemic recovery period. At P10, SEPs were immature and evoked activity was almost restricted to the somatosensory and motor cortices of the contralateral hemisphere. Peak and topographic analyses of epicranial potentials revealed that responses were profoundly depressed in both sensory and motor areas of HI-lesioned animals. At the end of the postnatal period at P21, responses involved networks in both hemispheres. SEP amplitude was still depressed in the injured sensory region, but it completely recovered in the motor area. These results suggest a process of large-scale network plasticity in sensorimotor circuits after perinatal ischemic injury. The model provides new perspectives for investigating the temporal and spatial characteristics of the recovery process following HI and eventually developing therapeutic interventions.

Desmosomal Dysfunction due to Mutations in Desmoplakin Causes Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is characterized by progressive degeneration of the right ventricular myocardium, ventricular arrhythmias, fibrous-fatty replacement, and increased risk of sudden death. Mutations in 6 genes, including 4 encoding desmosomal proteins (Junctional plakoglobin (JUP), Desmoplakin (DSP), Plakophilin 2, and Desmoglein 2), have been identified in patients with ARVD/C. Mutation analysis of 66 probands identified 4 variants in DSP; V30M, Q90R, W233X, and R2834H. To establish a cause and effect relationship between those DSP missense mutations and ARVD/C, we performed in vitro and in vivo analyses of the mutated proteins. Unlike wild-type (WT) DSP, the N-terminal mutants (V30M and Q90R) failed to localize to the cell membrane in desomosome-forming cell line and failed to bind to and coimmunoprecipitate JUP. Multiple attempts to generate N-terminal DSP (V30M and Q90R) cardiac-specific transgenes have failed: analysis of embryos revealed evidence of profound ventricular dilation, which likely resulted in embryonic lethality. We were able to develop transgenic (Tg) mice with cardiac-restricted overexpression of the C-terminal mutant (R2834H) or WT DSP. Whereas mice overexpressing WT DSP had no detectable histologic, morphological, or functional cardiac changes, the R2834H-Tg mice had increased cardiomyocyte apoptosis, cardiac fibrosis, and lipid accumulation, along with ventricular enlargement and cardiac dysfunction in both ventricles. These mice also displayed interruption of DSP-desmin interaction at intercalated discs (IDs) and marked ultra-structural changes of IDs. These data suggest DSP expression in cardiomyocytes is crucial for maintaining cardiac tissue integrity, and DSP abnormalities result in ARVD/C by cardiomyocyte death, changes in lipid metabolism, and defects in cardiac development.

Lesion Progression in apoE-Deficient Mice: Implication of Chemokines and Effect of the AT1 Angiotensin II Receptor Antagonist Irbesartan

We recently described that a treatment with the angiotensin AT1 receptor antagonist irbesartan inhibits atherosclerotic lesion development, macrophage accumulation, and monocyte chemoattractant protein-1 (MCP-1) as well as the chemokine KC expression in apolipoprotein E-deficient (apoE-deficient) mice. The present study addresses whether these and other chemokines are expressed not only during the initiation but also during the development of atherosclerotic lesions and whether irbesartan can inhibit the expression of these chemokines during lesion progression. The time course of lesion development was assessed in apoE-deficient mice aged 1 to 9 months and the relative expression of chemokines was quantified by RT-PCR. Significant lesion formation already appeared in 3-month-old apoE-deficient mice, and progressed further to the age of 9 months. The expression of MCP-1 and KC (the mouse homologue of Groalpha), was induced at 1 month in apoE-deficient as compared with wild type (C57/Bl6) mice, and was observed before any detectable histologic changes. MCP-1 and KC expression remained high during lesion progression. The expression of macrophage inflammatory protein-2 (MIP-2, the mouse Grobeta/gamma homologue) and macrophage inflammatory protein-1alpha (MIP-1alpha) was increased in lesions from 4-month-old mice onward, whereas Regulated upon Activation of Normal T-cells Expressed and Secreted (RANTES) was significantly induced in 6- to 9-month-old mice only. Irbesartan (50 mg/kg/d) administered from the age of 3 months onward significantly reduced the progression of the lesions as well as the expression of the chemokines. A short-term treatment with irbesartan significantly inhibited the expression of MCP-1 and KC, suggesting that activation of the renin-angiotensin system is involved in up-regulation of these chemokines and that this effect represents a potential mechanism by which irbesartan inhibits plaque development and progression.

Pathogenesis and control of bacterial speck, Pseudomonas syringae pv. tomato, on tomato

Bacterial speck of tomato, caused by Pseudomonas syringae pv. tomato, was observed to cause severe symptoms, especially on protected tomato crops, during the winter season in the coastal area of Lebanon. This study was conducted to investigate the aetiology and pathogenesis of the bacterium involved and the efficacy of different chemicals for the control of the disease. Biochemical, physiological and pathological tests verified the identity of the bacterium involved as P. s. tomato. Periodic histological sectioning of inoculated tomato leaves showed that bacterial cells resided and multiplied in depressions and around trichome bases for 24 h before penetration through stomata and trichome basal cells. The bacteria invaded intercellular spaces and caused cell lignification, collapse and shrinkage, 48 h after inoculation. Necrotic lesions filled with bacterial masses and collapsed lignified cells were readily observable at and after 72 h. No detectable histological changes were observed in the yellow halo region surrounding the necrotic leaf specks. A thermostable toxin was produced by the pathogen and is involved in chlorotic symptom expression. An antibiotic mixture of streptomycin + oxytetracy-cline was most effective in controlling infections followed by copper oxychloride + mancozeb, tribasic copper sulphate + sulphur, copper oxychloride and copper oxychloride + zineb.

Transient cerebral ischemia. Association of apoptosis induction with hypoperfusion.

Apoptosis is thought to be important in the pathogenesis of cerebral ischemia. The mechanism of apoptosis induction remains unclear but several studies suggest that it is preferentially triggered by mild/moderate microcirculatory disturbances. We examined in cats whether induction of apoptosis after 2.5 h of unilateral middle cerebral artery occlusion plus 10 h of reperfusion is influenced by the degree of cerebral microcirculatory disturbance. Quantitative monitoring over time of the disturbances of cerebral microcirculation in ischemic brain areas and evaluation of cytotoxic edema associated with perfusion deficits was achieved by using two noninvasive magnetic resonance imaging techniques: (a) high-speed echo planar imaging combined with a bolus of magnetic susceptibility contrast agent; and (b) diffusion-weighted imaging. Apoptosis-positive cells were counted in anatomic areas with different severity of ischemic injury characterized by magnetic resonance imaging, triphenyltetrazolium chloride, and hemotoxylin and eosin staining. The number of apoptosis-positive cells was significantly higher in anatomic areas with severe perfusion deficits during occlusion and detectable histologic changes 10 h after reperfusion. In contrast, in areas where perfusion was reduced but maintained during occlusion there were no detectable histological changes and significantly fewer apoptosis-positive cells. A similar number of cells that undergo apoptosis were shown in regions with transient or prolonged subtotal perfusion deficits. These results suggest that the apoptotic process is induced in the ischemic core and contributes significantly in the degeneration of neurons associated with transient ischemia.

Effects of acutely raising intracranial pressure on cardiac sympathetic efferent neuron function

To determine whether acutely raising intracranial pressure modifies the function of cardiac efferent autonomic neurons. The effects of suddenly raising intracranial pressure above systemic vascular pressure on heart rate, left atrial and left ventricular chamber pressures, as well as right and left ventricular intramyocardial pressures, were studied following removal of the adrenal glands from the circulation. Cardiac effects induced by systemic administration of nicotine, tyramine or isoproterenol were investigated before and after raising intracranial pressure: (1) in 9 dogs with neurally intact hearts in which cardiac release of catecholamines and intrinsic cardiac neuronal activity were studied; (2) in another 8 dogs in which intrathoracic autonomic neurons were disconnected from central neurons; (3) in another 8 dogs after decentralizing intrathoracic sympathetic but not parasympathetic neurons; (4) in 2 animals after decentralizing intrathoracic parasympathetic, not sympathetic neurons. Increasing intracranial pressure in neurally intact preparations induced ventricular augmentation followed by depression such that after 12 min of cerebral ischemia left ventricular systolic pressure was 62 +/- 5 mmHg. Isoproterenol and tyramine augmented right ventricular inotropism similarly before and after raising intracranial pressure, their effects on left ventricular systolic pressures being reduced secondary to the systemic vascular hypotension. Although nicotine excited intrinsic cardiac neurons similarly before and after raising intracranial pressure, it failed to enhance cardiac liberation of noradrenaline after compared to before raising intracranial pressure. Nicotine-induced ventricular augmentation was obtunded after brain death despite the fact that ventricular myocytes underwent no detectable histological changes. In contrast, nicotine induced similar cardiac augmentation before and after raising intracranial pressure when intrathoracic autonomic neurons or when intrathoracic sympathetic, not parasympathetic neurons, were decentralized. Cardiac sympathetic efferent neuronal function is obtained by acutely raising intracranial pressure.

Retinoids and photodamage.

Extensive well-controlled clinical studies performed over the past 5 years have demonstrated a consistent, dose-dependent, statistically significant improvement in the appearance of photodamaged skin after 3-6 months of daily treatment with topical 0.001-0.1% tretinoin cream. Clinical changes included decreases in surface roughness, irregular pigmentation, fine and coarse wrinkling, and sallowness. Actinic keratoses have also been reported to decrease in size and number. Blinded analysis of biopsies from more than 500 subjects showed that there was compaction of the stratum corneum, an increase in the number of granular layers, thickening of the epidermis and a decrease in epidermal melanin. There were no detectable histological changes in any dermal parameters. The specific cellular mechanisms by which retinoic acid (RA) exerts its beneficial effect on photodamaged skin are currently the subject of intensive investigation. It is well established that RA enters the nucleus where it binds to an RA receptor (RAR), and that the RA-RAR complex then binds to specific RA response elements in the DNA, modulating the expression of target genes. It is thus likely that RA improves at least some aspects of photoageing by modifying cellular differentiation programmes, as retinoids have been shown to do during embryogenesis, in malignantly transformed cells and in skin affected by certain dermatoses.

Comparative study of 8-monohydromirex and mirex toxicity in male rats

Male rats were fed 0, 0.5, 5.0, 50, and 75 ppm mirex or 8-monohydromirex for 28 days. There were no consistent differences between weight gain of treated or control groups. There were significant increases in LW/BW in the 5, 50, and 75 ppm mirex and 8-monohydromirex treatment groups. Serum β-glucuronidase was elevated in the 0.5, 50, and 75 ppm mirex treated groups, and was elevated in the 5, 50, and 75 ppm 8-monohydromirex treated groups. There were no consistent changes in serum sorbitol dehydrogenase in any treatment group, but there were significant increases in liver sorbitol dehydrogenase at all levels for both toxicants. Hepatic microsomal parameters were induced by both compounds. No consistent toxic effects resulting from mirex or 8-monohydromirex treatment were indicated by serum glucose, protein, and cholesterol or by selected hematological factors. The histological changes observed in the livers of animals treated with mirex and 8-monohydromirex included cell swelling with increased cytoplasmic density; a dense homogenous region centered around the nuclear area; hyaline or myelin-like cytoplasmic inclusions appearing in some tissue sections of the highest treatment levels; and lipidosis. Histological changes in testes of treated rats were less obvious than lesions observed in the liver. There was a loss of staining intensity of the seminiferous tubules associated with hypocellularity of the tubules. Decreased spermatogenesis was evident in three rats from the high dose groups. Both compounds produced detectable histological changes in the thyroid glands at the 75 ppm treatment level. There did not appear to be any consistently significant differences between the toxic effects, either qualitative or quantitative, of mirex and 8-monohydromirex in rats fed either compound for 28 days.

Complement-independent nephrotoxic nephritis in the guinea pig

Immunologic mechanisms of proteinuria were investigated in guinea pigs (GP) injected with sheep antiserum (NTS) to GP glomerular basement membrane (GBM). Linear deposition of sheep gamma 1 and gamma 2 IgG led to a prompt but transient (36 hr) increase in albumin excretion from control values of 0.026 +/- 0.013 mg/hr to maximal values of 26+/-12.1 mg/rh at six hours without detectable histologic or electron microscopic changes except for decreased staining for glomerular polyanion and epithelial cell foot process fusion. GBM permeability to anionic ferritin was not increased during proteinuria. Anti-GBM antibody deposits did not fix GP C3 or C4 in vivo or in vitro. NTS-induced proteinuria was the same in guinea pigs that were normal, greater than 95% depleted of C3 through C9, genetically deficient in C4, and depleted of circulating polymorphonuclear leukocytes (PMN). Prior administration of antihistamines, steroids, azathioprine, colchicine, indomethacin, heparin, aprotinin (Trasylol), and niridazole also failed to reduced proteinuria. Initial proteinuria subsided by 36 hr, did not recur despite linear deposition of GP gemma 1 and gemma 2 after day seven, and antibody to GMB-bound sheep globlin. In the GP nephrotoxic nephritis model, anti-GBM antibody deposits apparently mediate increased permeability to albumin by a currently undefined mechanism which is independent of complement, PMN, and other know mediators of inflammation.

Alterations in the mouse cecum and its flora produced by antibacterial drugs.

Addition of penicillin, Terramycin, or kanamycin to the drinking water of adult mice rapidly induced in them an enlargement of the cecum. In all animals, this occurred within 12 hr after the beginning of drug administration-the effect being most pronounced with penicillin. The cecums remained enlarged and generally continued to increase in size as long as the antibacterial drugs were administered. The increase in wet weight of the cecums was due primarily to an accumulation of water in the lumens during the first 24-48 hr of drug administration. At that time, there were no detectable histological changes in any case, but the bacteriological picture differed from drug to drug. The cecums were free of bacteria in animals receiving penicillin, fusiform-shaped bacteria and bacteroides were present in those receiving Terramycin, and lactobacilli and bacteroides in those receiving kanamycin. After the initial 48 hr, an abundant and complex secondary microflora developed in all treated animals, its composition being characteristic for each type of antibacterial drug. When penicillin was administered for 2 wk, the cecal weights and microbial populations did not return to normal levels for over 14 days after discontinuance of the drug. This recovery period could be shortened to 10 days by giving the mice food contaminated with cecal homogenates prepared from normal animals. A period of 7 or 8 days was required for the cecal weights and microflora to reach normal levels when the administration of penicillin lasted only 24 hr; this period could not be shortened by giving the animals contaminated food. The effects of drugs on the size and bacterial contents of the cecum have been discussed in the light of earlier findings concerning the characteristics of the huge cecums uniformly found in germfree mice. Taken together, these observations support the hypothesis that certain elements of the intestinal microflora-not yet completely identified-play an essential role in maintaining the integrity of the water-transport mechanism in the intestinal epithelium.

Histochemical study on chromatolytic neurons.

SEVERE injury to the axon produces detectable histological changes in the cell body as well as proximal and distal parts of the injured fiber. This retrograde reaction in the perikaryon is commonly known as chromatolysis or chromolysis because of the apparent decrease in basophilic material in the cytoplasm. In crush injury of the axon with preservation of the sheath (termed axonotmesis by Seddon 1 ) regeneration of the neuron may occur in a shorter time, than after complete section of the nerve. There have been many studies of motoneurons during degeneration and regeneration, 2-8 but histochemical studies of the enzymes in these neurons are few. Different authors have investigated alkaline and acid phosphatases, thiamine pyrophosphatase (TPPase), succinic dehydrogenase, and cytochrome oxidase in chromatolytic neurons 9-12 but metabolic significance of these changes is not known. In the present study we have investigated a number of oxidative and hydrolytic enzymes by histochemical