Masticatory muscle activity during deliberately performed oral tasks

The aim of this study was to investigate masticatory muscle activity during deliberately performed functional and non-functional oral tasks. Electromyographic (EMG) surface activity was recorded unilaterally from the masseter, anterior temporalis and suprahyoid muscles in 11 subjects (5 men, 6 women; age = 34.6 +/- 10.8 years), who were accurately instructed to perform 30 different oral tasks under computer guidance using task markers. Data were analyzed by descriptive statistics, repeated measurements analysis of variance (ANOVA) and hierarchical cluster analysis. The maximum EMG amplitude of the masseter and anterior temporalis muscles was more often found during hard chewing tasks than during maximum clenching tasks. The relative contribution of masseter and anterior temporalis changed across the tasks examined (F 5.2; p < or = 0.001). The masseter muscle was significantly (p < or = 0.05) more active than the anterior temporalis muscle during tasks involving incisal biting, jaw protrusion, laterotrusion and jaw cupping, the difference being statistically significant (p < or = 0.05). The anterior temporalis muscle was significantly (p < or = 0.01) more active than the masseter muscle during tasks performed in intercuspal position, during tooth grinding, and during hard chewing on the working side. Based upon the relative contribution of the masseter, anterior temporalis, and suprahyoid muscles, the investigated oral tasks could be grouped into six separate clusters. The findings provided further insight into muscle- and task-specific EMG patterns during functional and non-functional oral behaviors.

Long-term follow-up of thoracoscopic talc pleurodesis for primary spontaneous pneumothorax

The aim of the present study was to evaluate the long-term outcome of patients with primary spontaneous pneumothorax treated with talc pleurodesis. A follow-up study was undertaken in all patients with primary spontaneous pneumothorax who underwent talc pleurodesis for prolonged air leak or recurrence using thoracoscopy. In total, 112 patients underwent pleurodesis and follow-up data was obtained in 63 (56%) patients: 45 patients were available for clinical follow-up, 14 for telephone follow-up and four were dead. The causes of death were unrelated to the pleurodesis. There were no episodes of acute respiratory failure following pleurodesis. A total of 56 (95%) out of the cohort of 59 patients had a successful pleurodesis. Surgical pleurectomy was required in three (5%) patients for persistent air leak. Median duration of follow-up after talc pleurodesis was 118 months. Long-term success was observed in 53 (95%) out of 56 patients. Recurrent pneumothorax was observed in three (5%) out of 56 patients. Patients with successful talc pleurodesis had a median forced vital capacity (FVC) of 102% and median total lung capacity of 99% at follow-up. Comparing smokers and nonsmokers, the forced expiratory volume in one second (FEV(1)) was significantly lower in smokers and there was a tendency for the FEV(1)/FVC ratio to be lower in smokers. Talc pleurodesis in patients with primary spontaneous pneumothorax via thoracoscopy is an effective procedure associated with normal lung function in patients who do not smoke.

[Antibiotics, purpura and ulcers: a leukocytoclastic vasculitis after clarithromycin]

HISTORY AND CLINICAL FINDINGS

A 47- year-old woman presented with palpable purpura of both lower limbs after taking six tablets of clarithromycin for pneumonia.

INVESTIGATIONS

Apart from mild microhematuria there were no other signs of organ involvement. Histology of a skin biopsy revealed a hypersensitivity vasculitis.

TREATMENT AND COURSE

A hypersensitivity vasculitis due to clarithromycin was the cause of the purpura. The course of this hypersensitivity vasculitis was severe and protracted over weeks with formation of deep ulcerative skin lesions.

CONCLUSION

Clarithromycin may be the cause of a hypersensitivity vasculitis: often the course of the disease is mild, but it may also lead to severe local complications. The diagnosis of hypersensitivity vasculitis can be made in a patient over 16 years of age if there is the combination of a triggering substance, purpura and leukocytoclastic vasculitis. The most important step is immediate withdrawal of the causative agent. A beneficial effect of treatment with steroids on prognosis is not proven.

Early embryogenesis in Arabidopsis thaliana. I. The mature embryo sac

Arabidopsis thaliana has a seven-celled eight-nucleate megagametophyte of the Polygonum type; each cell type displays a different form of structural specialization. The egg apparatus cells are highly polarized; the egg has a large micropylar vacuole and chalazally sited nucleus, whereas the opposite is true for the synergids. At the chalazal region of the egg apparatus cells there are no cell wall boundaries, although their plasmalemmas are in intimate contact. The common wall between the two synergids is thin and irregular and contains plasmodesmatal connections. The synergid cytoplasm is rich in organelles; profiles of rough endoplasmic reticulum appear in masses of parallel stacked cisternae, and large accumulations of mitochondria occur adjacent to the filiform apparatus. The egg cell cytoplasm is quiescent; ribosome concentration and frequencies of dictyosomes and endoplasmic reticulum are noticeably lower and plastids are poorly differentiated. The central cell is long and vacuolate with a large diploid nucleus; fusion of the polar nuclei occurs prior to embryo sac maturity. The cytoplasm contains numerous starch-containing plastids accumulated in a shell around the nucleus. A high ribosome concentration and the absence of vacuoles and dictyosomes typifies the antipodal cell cytoplasm. All antipodal cells are interconnected by plasmodesmata as well as being connected to the nucellus and central cell. Key words: Arabidopsis, embryo sac, embryogenesis, cell specializations, stereology.