Pulsatile luteinizing hormone and follicle-stimulating hormone secretion and gonadotropin subunit mRNA levels in the ovariectomized GPR-4 transgenic rat

Genetic targeting of the cAMP-specific phosphodiesterase 4D1 (PDE4D1) to gonadotropin-releasing hormone (GnRH) neurons in the GPR-4 transgenic rat resulted in decreased luteinizing hormone (LH) pulse frequency in castrated female and male rats. A similar decrease in the intrinsic GnRH pulse frequency was observed in GT1 GnRH cells expressing the PDE4D1 phosphodiesterase. We have extended these findings in ovariectomized (OVX) GPR-4 rats by asking what effect transgene expression had on pulsatile LH and follicle-stimulating hormone (FSH) secretion, plasma and pituitary levels of LH and FSH, and levels of the alpha-glycoprotein hormone subunit (alpha-GSU), LH-beta and FSH-beta subunit mRNAs. In OVX GPR-4 rats the LH pulse frequency but not pulse amplitude was decreased by 50% compared to wild-type littermate controls. Assaying the same samples for FSH, the FSH pulse frequency and amplitude were unchanged. The plasma and anterior pituitary levels of LH in the GPR-4 rats were significantly decreased by approximately 45%, while the plasma but not anterior pituitary level of FSH was significantly decreased by 25%. As measured by real-time RT-PCR, the mRNA levels for the alpha-GSU in the GPR-4 rats were significantly decreased by 41%, the LH-beta subunit by 38% and the FSH-beta subunit by 28%. We conclude that in the castrated female GPR-4 rats the decreased GnRH pulse frequency results in decreased levels of LH and FSH and in the alpha- and beta-subunit mRNA levels.     

Factors influencing the growth and viability of Actinobacillus actinomycetemcomitans

The metabolic requirements for the routine growth of Actinobacillus actinomycetemcomitans were investigated by the addition of nutrients to conventional bacteriological and tissue culture media. Commonly used tissue culture media required fetal bovine serum as an additive to sustain bacterial growth rates comparable to those obtained with bacteriological media. The addition of increasing concentrations of yeast extract to bacteriological medium increased the growth rate of several A. actinomycetemcomitans strains. In an attempt to identify the components of yeast extract that enhanced the growth of A. actinomycetemcomitans , a number of vitamins, essential and non-essential amino acids were tested for their role in promoting growth. The addition of L-cystine resulted in bacterial growth rates comparable to those with yeast extract. Thiamine increased the growth of several A. actinomycetemcomitans strains but did not result in growth rates comparable to those with yeast extract. The addition of physiological concentrations of steroid hormones to bacteriological medium enhanced the growth of A. actinomycetemcomitans. Additional iron compounds and fat-soluble vitamins had no influence on A. actinomycetemcomitans growth. However, the requirement of iron for bacterial growth remains unclear. The optimal pH range for growth of A. actinomycetemcomitans was between pH 7.0–8.0 in a medium containing 0.5–1% Nacl. Several interesting observations on the viability of A. actinomycetemcomitans were made. A rapid reduction of A. actinomycetemcomitans viability occurred following suspension in distilled water. The presence of the detergent Triton X-100 at concentrations above 2% (v/v) also decreased the viability of A. actinomycetemcomitans within 10 min.     

A sero-epidemiologic study of a water-borne epidemic of viral hepatitis in Kolhapur City, India.

Between February and March 1981 an epidemic of hepatitis occurred in Kolhapur City, Maharashtra State, India. Approximately 1200 cases of jaundice were reported; more than 300 patients were hospitalized and three died. The epidemiological investigations showed a distinct concentration of cases in municipal ward E of the city. Investigations of the ward E water supply system disclosed gross contamination of raw water with sewage at source. The serological studies revealed that the aetiological agent responsible for this epidemic was neither hepatitis A virus nor hepatitis B virus but was likely to have been due to a non-A, non-B hepatitis virus.     

Identification of oral bacterial species associated with halitosis

BACKGROUND: The authors examined the tongue bacteria associated with oral halitosis (bad breath originating from the oral cavity), focusing on noncultivable bacteria-bacteria that cannot be identified by bacterial culture techniques. METHODS: The authors took samples from the dorsal tongue surface of eight adult subjects with halitosis and five control subjects who did not have halitosis. They identified the bacteria in these samples by using both anaerobic culture and direct amplification of 16S ribosomal DNA, a method that can identify both cultivable and noncultivable microorganisms. They analyzed the resulting microbiological data using chi(2) and correlation coefficient tests. RESULTS: Clinical measures of halitosis were correlated highly with each other and with tongue coating scores. Of 4,088 isolates and phylotypes identified from the 13 subjects, 32 species including 13 noncultivable species were found only in subjects with halitosis. Solobacterium moorei was present in all subjects with halitosis but not in any control subjects. CONCLUSIONS: Subjects with halitosis harbor some bacterial species on their dorsal tongue surfaces that are distinct from bacterial species found in control subjects. This finding is consistent with the hypothesis that halitosis has a microbial etiology. CLINICAL IMPLICATIONS: Like other oral diseases with microbial etiology, halitosis may be amenable to specific and nonspecific antimicrobial therapy targeted toward the bacteria associated with it.     

Transformation of Actinobacillus actinomycetemcomitans by electroporation, utilizing constructed shuttle plasmids.

Actinobacillus actinomycetemcomitans, a periodontal pathogen, has been strongly implicated in human periodontal disease. Advances in the molecular analysis of A. actinomycetemcomitans virulence factors have been limited due to the unavailability of systems for genetic transfer, transposon mutagenesis, and gene complementation. Slow progress can be traced almost exclusively to the lack of gene vector systems and methods for the introduction of DNA into A. actinomycetemcomitans. An electrotransformation system that allowed at least five strains of A. actinomycetemcomitans to be transformed with stable shuttle plasmids which efficiently replicated in both Escherichia coli and A. actinomycetemcomitans was developed. One plasmid, a potential shuttle vector designated pDL282, is 5.7 kb in size, has several unique restriction enzyme sites, and codes for resistance to spectinomycin and ampicillin. E. coli and A. actinomycetemcomitans were transformed with equal efficiencies of approximately 10(5) transformants per micrograms of DNA. Similar transformation efficiencies were obtained whether the plasmid DNA was isolated from A. actinomycetemcomitans or E. coli. In addition, frozen competent cells of A. actinomycetemcomitans yielded comparable efficiencies of transformation. Restriction enzyme analysis of pDL282 isolated after transformation confirmed the presence of intact donor plasmids. A plasmid isolated from A. pleuropneumoniae was also capable of transforming some isolates of A. actinomycetemcomitans, although generally at a lower frequency. The availability of these shuttle plasmids and an efficient transformation procedure should significantly facilitate the molecular analysis of virulence factors of A. actinomycetemcomitans.     

Grid cells generate an analog error-correcting code for singularly precise neural computation

Entorhinal grid cells in mammals fire as a function of animal location, with spatially periodic response patterns. This nonlocal periodic representation of location, a local variable, is unlike other neural codes. There is no theoretical explanation for why such a code should exist. We examined how accurately the grid code with noisy neurons allows an ideal observer to estimate location and found this code to be a previously unknown type of population code with unprecedented robustness to noise. In particular, the representational accuracy attained by grid cells over the coding range was in a qualitatively different class from what is possible with observed sensory and motor population codes. We found that a simple neural network can effectively correct the grid code. To the best of our knowledge, these results are the first demonstration that the brain contains, and may exploit, powerful error-correcting codes for analog variables.     

Working memory templates are maintained as feature-specific perceptual codes

Working memory (WM) representations serve as templates that guide behavior, but the neural basis of these templates remains elusive. We tested the hypothesis that WM templates are maintained by biasing activity in sensoriperceptual neurons that code for features of items being held in memory. Neural activity was recorded using event-related potentials (ERPs) as participants viewed a series of faces and responded when a face matched a target face held in WM. Our prediction was that if activity in neurons coding for the features of the target is preferentially weighted during maintenance of the target, then ERP activity evoked by a nontarget probe face should be commensurate with the visual similarity between target and probe. Visual similarity was operationalized as the degree of overlap in visual features between target and probe. A face-sensitive ERP response was modulated by target-probe similarity. Amplitude was largest for probes that were similar to the target, and decreased monotonically as a function of decreasing target-probe similarity. These results indicate that neural activity is weighted in favor of visual features that comprise an actively held memory representation. As such, our findings support the notion that WM templates rely on neural populations involved in forming percepts of memory items.     

Multi-drug resistant Acinetobacter species from various clinical samples in a tertiary care hospital from South India

Background

Acinetobacter species are gram-negative coccobacilli belonging to the group of Non-Fermenting Gram-Negative Bacilli, which are ubiquitous in nature. They cause outbreaks in intensive care units and healthcare settings, and are becoming increasingly drug resistant.

Aims

To determine the prevalence of multi-drug resistant Acinetobacter species from various clinical samples.

Method

Clinical samples were processed as per standard microbiological techniques. Antibiotic susceptibility testing was carried out on all the Acinetobacter isolates by Kirby- Bauer disc diffusion method as per CLSI guidelines.

Results

A total of 122 Acinetobacter spp. were isolated. 110 (90.16 per cent) were from inpatients, and 12 (9.83 per cent) were from outpatients. Out of 122 isolates, 44 (36.06 per cent) were from the ICU. The majority of the isolates, 47 (38.52 per cent), were from pus samples followed by 25 (20.49 per cent) from endotracheal tube aspirate. Out of 122 isolates, 87 (71.31 per cent) were multi-drug resistant of which 15 (12.29 per cent) were resistant to all drugs tested.

Conclusion

Acinetobacter infections associated with multi-drug resistant and pan-resistant strains have emerged as important nosocomial pathogens in our setting.     

Cytotoxicity and genotoxicity assessment of Euphorbia hirta in MCF-7 cell line model using comet assay

Objective

To evaluate the cytotoxicity and genotoxicity activity of Euphorbia hirta (E. hirta) in MCF-7 cell line model using comet assay.

Methods

The cytotoxicity of E. hirta extract was investigated by employing brine shrimp lethality assay and the genotoxicity of E. hirta was assessed by using Comet assay.

Results

Both toxicity tests exhibited significant toxicity result. In the comet assay, the E. hirta extract exhibited genotoxicity effects against MCF-7 DNA in a time-dependent manner by increasing mean percentage of DNA damage. The extract of E. hirta showed significant toxicity against brine shrimp with an LC₅₀ value of 620.382 µg/mL (24 h). Comparison with positive control potassium dichromate signifies that cytotoxicity exhibited by the methanol extract might have moderate activity.

Conclusion

The present work confirmed the cytotoxicity and genotoxicity of E. hirta. However, the observed toxicity of E. hirta extracts needs to be confirmed in additional studies.