A positive correlation between occlusal trauma and peri-implant bone loss: literature support

The relationship between occlusal overload and peri-implant bone loss remains a controversial topic in implant dentistry. A causal relationship between the incidence of marginal bone loss next to an implant and occlusal overload implies a treatment plan and occlusal scheme would benefit from a force management approach. A MEDLINE-assisted and hand search of peer-reviewed English literature and relative textbooks were used for a selective review of articles addressing biomechanical stress and bone loss in cellular biomechanics, engineering principles, mechanical properties of bone, animal studies, clinical reports, bone physiology, and implant design biomechanics. These papers demonstrate occlusal overload on implants may increase the incidence of marginal bone loss.     

Clinical relevance of Mycobacterium tuberculosis plcD gene mutations

To identify Mycobacterium tuberculosis virulence factors, we integrated comparative genomics and epidemiologic data analysis to investigate the relationship between certain genomic insertions and deletions in the phospholipase-C gene D (plcD) with the clinical presentation of tuberculosis (TB). Four hundred ninety-six well-characterized M. tuberculosis clinical isolates were studied. Approximately 30% (147) of the isolates had an interruption of the plcD gene. Patients infected with the plcD mutant were twice as likely to have extrathoracic disease as those infected by a strain without an interruption (adjusted odds ratio, 2.19; 95% confidence interval, 1.27, 3.76). When we limited the analysis to the 275 isolates with distinct DNA fingerprint patterns, we observed the same association (adjusted odds ratio, 2.74; 95% confidence interval, 1.35, 5.56). Furthermore, the magnitude of the association appeared to differ with the type of extrathoracic TB. Our findings suggest that the plcD gene of M. tuberculosis is potentially involved in the pathogenesis of TB, and the clinical presentation of the disease may be influenced by the genetic variability of the plcD region.     

Pancreatic pseudocyst simulating perinephric abscess

A case of pseudocyst of the pancreas simulating perinephric abscess is described. This condition is rare compared with most reported cases of pseudocyst causing pyelographic abnormalities by extrinsic compression. Spontaneous rupture of the pseudocyst is proposed as the mechanism by which the normally protective Gerota's fascia is penetrated.     

Neuropsychological Correlates of the Electroencephalogram in Epileptics: II. The Waking Posterior Rhythm and its Interaction with Epileptiform Activity

Relationships between psychological functions and waking dominant posterior rhythm frequency (DPRF) of the EEG were evaluated with and without simultaneous evaluation of epileptiform discharges. Ninety adult epileptics with uncontrolled seizure disorders treated solely by diphenylhydantoin underwent EEGs during wakefulness and administrations of an extensive battery of neuropsychological tests. The DPRF was particularly related to abilities simultaneously requiring attention an complex mental manipulations. Rhythms slower than 7.5-8.0 Hz were accompanied by relatively poorer performance than rhythms which were faster. When epileptiform discharges were considered in combination with the DPRF, larger differences in abilities were demonstrated, and the psycholoigcal correlates tended to be more substantial for the epileptiform discharge variable than for the DPRF variable. The selection of tests employed and the range of rhythms assessed are critical to these findings, and the substantial construction of these variables by many previous investigators is believed to be related to the negative findings often reported.     

Kynurenic acid inhibits synaptic and acidic amino acid-induced responses in the rat hippocampus and spinal cord

Kynurenic acid, a tryptophan metabolite, inhibits excitatory synaptic transmission in the rat hippocampal slice and the isolated immature rat spinal cord, but does not affect membrane potential or input resistance of hippocampal CA1 pyramidal cells. Kynurenic acid also antagonizes responses induced in the dentate gyrus by excitatory amino acids, particularly N-methyl-DL-aspartate and the endogenous excitant quinolinic acid. These results indicate that kynurenic acid antagonizes synaptic transmission probably by blocking postsynaptic transmitter receptors at putative amino acid mediated synapses.