Interleukin-18 null mice show diminished microglial activation and reduced dopaminergic neuron loss following acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treatment

Recent reports have revealed an involvement of microglial cells in dopaminergic neurodegeneration. In the present study, we tested the hypothesis that interleukin-18 (IL-18) plays a role in the microglial activation. The present study investigated microglial activation and dopaminergic neurodegeneration in substantia nigra pars compacta (SNpc) following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment in wild type (WT) and IL-18 knockout (KO) mice. The number of dopaminergic neuron loss in WT mice was significantly decreased 7 days after MPTP treatment compared with IL-18 KO mice. In WT mice microglial activation occurred in the SN at 1 day after MPTP treatment, progressively increased within the SNpc until 7 days post MPTP, and subsided by 14 days. In contrast, in IL-18 KO mice microglial activation occurred in the SN at 1 day post-MPTP, and decreased by 7 days, earlier than in WT mice. The lesser microglial activation and dopaminergic neurodegeneration in the SNpc following MPTP treatment in WT indicates the possibility that IL-18 may participate in microglial activation and dopaminergic neurodegeneration.     

Immunogenicity of recombinant Plasmodium falciparum SERA proteins in rodents

We have expressed defined regions of the serine-repeat antigen (SERA) of the Honduras-1 strain of Plasmodium falciparum in the yeast Saccharomyces cerevisiae. Amino-terminal domains of the natural SERA protein have been shown previously to be targets for parasite-inhibitory murine monoclonal antibodies. Two recombinant SERA antigens were selected for purification and immunological analysis. The first (SERA 1), corresponding to amino acids 24-285 of the natural SERA precursor, was expressed by the ubiquitin fusion method. This allowed for in vivo cleavage by endogenous yeast ubiquitin hydrolase, and subsequent isolation of the mature polypeptide. The second, larger protein (SERA N), encompassing amino acids 24-506, was expressed at only low levels using this system, but could be isolated in high yields when fused to human gamma-interferon (gamma-IFN). Each purified protein was used to immunize mice with either Freund's adjuvant or a muramyl tripeptide adjuvant that has been used in humans. Sera from immunized mice were shown to be capable of in vitro inhibition of invasion of erythrocytes by the Honduras-1 strain of P. falciparum. The results suggest that a recombinant SERA antigen may be an effective component of a candidate malaria vaccine.     

Developmental changes in the behavioral and autonomic effects of kappa opioid receptor stimulation of the midbrain periaqueductal gray

Kappa opioid receptors stimulation with U50,488 is known to modulate behaviors during the early postnatal period, but the specific neuroanatomical locus of many of these effects is unexplored. In the present study, we infused U50,488 into the midbrain periaqueductal gray (PAG) and investigated the effects of this drug on behavior and heart rate of 1-, 2-, and 3-week-old rats. U50,488 increased activity most potently in 1- and 2-week-old subjects. Ultrasonic vocalization (USV) production was increased in 1-week-old subjects, but not in 2- or 3-week-old pups. Heart rate changes were similarly seen in younger aged subjects. At 1 week, U50,488 decreased heart rate, but at 2 weeks it increased heart rate. There was no effect of this drug on heart rate at 3 weeks. At 1 week, USVs were more potently elicited from dorsal than lateral PAG infusion sites. No other site-specific effects within the PAG were seen. The age-related decline in behavioral effects elicited by U50,488 is consistent with other published reports, and to the extent that kappa receptor activity mediates infant separation responses, implicates the PAG as a modulator of those responses.     

Typhus and typhuslike rickettsiae associated with opossums and their fleas in Los Angeles County, California.

The recent discovery of cat fleas (Ctenocephalides felis) infected with a typhuslike rickettsia (designated the ELB agent) raises the question of whether similar rickettsial infections exist in wild cat flea populations. We verified the presence of the ELB agent and Rickettsia typhi in urban and suburban areas of Los Angeles, Calif. Opossums trapped in close proximity to the residences of human murine typhus cases in Los Angeles county and other areas within the city of Los Angeles were tested for the presence of typhus group rickettsiae by the polymerase chain reaction (PCR). The presence of rickettsiae in the spleen tissues of three opossums (n = 9) and in 66 opossum fleas (n = 205) was determined by PCR and was verified by dot blot and Southern transfer hybridization. Further analysis of the amplified PCR products generated by a series of primer pairs derived from either the 17-kDa antigen gene or the citrate synthase gene revealed that both R. typhi and the ELB agent were present in the tested samples. Dual infection was not noted in the samples; however, the fleas were infected with either R. typhi or the ELB agent. The presence of the ELB agent in the cat flea population may have implications for public health. Whether this agent is responsible for the mild cases of human murine typhus in urban and suburban areas of Los Angeles or in other endemic foci remains to be determined.     

The congo red stain revisited

The Congo red stain has undergone several modifications since it was first used by Bennhold in 1922 in order to increase the specificity for staining amyloid. Most of the laboratories in the United States use the method of Puchtler which uses alkaline Congo red solution. Some of the variables associated with the procedure were investigated by us. Our results showed the following: (1) amyloid showed green birefringence at all levels between 4 to 12 mu thick sections with better visualization of small deposits with increased thickness. Best results were obtained with 8 mu thick sections; (2) omission of the pretreatment with alkaline alcoholic solution of sodium chloride (NaCl) did not affect the sensitivity of the method; (3) the use of polar mounting media had no effect on amyloid and collagen birefringence; (4) 50 percent saturation of the Congo red staining solution with NaCl caused strong staining of collagen, elastic fibers and eosinophilic granules. In addition, collagen showed green birefringence and dichroism and its differentiation from amyloid became difficult; and (5) using the staining solution fully saturated with NaCl, no positive staining was seen with tissues other than amyloid. Collagen and elastic fibers showed red fluorescence which was of less intensity than amyloid. It is our conclusion that the method of Puchtler for detecting amyloid gives better results if the staining solution is fully saturated with NaCl. The pretreatment step may be deleted without compromising the quality of staining. Improved staining of amyloid enhances the specificity of green birefringence, dichroism, and red fluorescence.     

Use of lectin histochemistry in pancreatic cancer.

Lectin peroxidase histochemical analysis was carried out on pancreatic tissue from patients with pancreatic carcinoma and chronic pancreatitis and from subjects with normal pancreas to find a tumour specific pattern of lectin binding that would aid histological and cytological diagnosis. There were striking differences between the lectin binding characteristics of the different cell types in the normal pancreas. Acinar cells were uniformly positive for binding with wheat germ agglutinin and soy bean agglutinin while islet cells were usually negative for these lectins. Ulex europaeus I lectin however, was found not to be specific for endothelium, showing positivity also for acinar and ductal tissue. Griffonia simplicifolia II lectin was found to be highly specific for ductal epithelium, and because of this was tested in a hamster pancreatic cancer model where it was not specific for ductal epithelium, reflecting differing carbohydrate expression in the hamster pancreas. Pancreatic carcinomas and chronic pancreatitis bound all five lectins without any qualitative distinction from each other or from normal pancreatic tissue, but there was increased intensity of peanut agglutinin binding to secreted mucins in pancreatic carcinoma, which may be of potential use in radiolabelled lectin scanning.     

A reappraisal of pre-transfusion testing procedures in a hospital blood bank

In recent years, experience with screening protocols for the detection of red cell antibodies has led to a reappraisal of pre-transfusion testing procedures. In the U.S.A. in particular, it has become accepted practice to perform only an antiglobulin crossmatch when an antibody screen has been negative. There is now debate in that country regarding the necessity of retaining even the antiglobulin crossmatch. In this laboratory, as is usual in Australia, room temperature, enzyme and antiglobulin tests are used for both antibody screening and crossmatching. A review was therefore conducted of the results of screening 58,227 samples from approximately 40,000 patients, involving 126,771 crossmatched blood units over a 53 mth period. Eight hundred and seventy-two red cell antibodies were detected in 718 patients. Forty-four of these antibodies were detected only in the crossmatch, and of these 23 were of potential clinical significance. Fourteen of the 23 were detected by the antiglobulin test, 8 by an enzyme test and only 1 by the saline method. Of 107 antibodies detected only in the room temperature phase, none were of clinical significance. The results indicate that exclusion of room temperature tests from all pre-transfusion testing, and deletion of enzyme tests from the crossmatch will not compromise patient safety.     

Technical quality control in histopathology.

A pilot scheme for technical quality control in histopathology is described. The test material used and the methods of assessment and reporting are detailed. The scheme outlines not only interlaboratory comparison of technical performance but also provides a method of sharing uncommon material.