Tissue fixation security in transosseous rotator cuff repairs: a mechanical comparison of simple versus mattress sutures

The primary purpose of this investigation was to compare tissue fixation security by simple sutures versus mattress sutures in transosseous rotator cuff repair. These two repair techniques were each performed in 17 human cadaver shoulders, with two bone tunnels being used for the repair by two simple sutures and two other bone tunnels being used for the repair by one mattress suture. The repairs were loaded to failure in a servohydraulic materials test system. Rotator cuff repair by simple sutures was found to be significantly stronger than repair by mattress sutures (P = .0007). The average ultimate load to failure for the simple suture construct (189.62 N) was 39.72% greater than that for the mattress suture construct (135.71 N). Most of the failures occurred by suture breakage at the knot. Load-sharing by multiple suture tails and multiple knots in the simple suture configuration likely contributed to its superior strength characteristics compared with the mattress suture configuration.     

Primary intrathoracic lymphangioma masquerading as teratoma

Two cases of cystic hygroma arising as a primary lesion in the chest are presented. Because of calcifications discovered on CT and because of the anterior location of the mass in both cases, teratoma was the first diagnostic consideration. However, after surgical removal, histologic study determined that both lesions were cystic hygromas with areas of scattered calcification probably secondary to hemorrhage. These cases are presented because of the remarkable similarity of their imaging features to those of teratoma.     

Ginkgolides antagonizing some effects of platelet-activating factor in vitro

The mixture of platelet-activating factor (PAF) and platelets produced significant contraction of guinea pigs' bronchus, while the contraction induced by PAF alone was mild relatively, the IC50 were 6.14 x 10(-7) mol/L and 6.32 x 10(-4) mol/L respectively. There was significant difference between these two groups (P < 0.05). When the platelets were pre-incubated with ginkgolides for 10 minutes in Tris-Tyrode's buffered saline, effects of the PAF and platelets mixture were significantly inhibited (P < 0.01). Exposure of guinea pigs' bronchus to PAF in vitro resulted in a loss of beta-adrenergic receptors and responses to isoproterenol, and this effect of PAF was prevented by prior incubation of the guinea pigs' bronchus with ginkgolides (P < 0.05). The results showed ginkgolides were a potent PAF antagonist.     

Investigation of the mechanism underlying the inhibitory effect of heterologous ras genes in plant cells

The ras genes from yeast and mammalian cells were fused to plant expression promoters, and introduced into plant cells via Agrobacterium, to study their effect on cell growth and development. All introduced ras genes had a strong inhibitory effect on callus and shoot regeneration from plant tissues. This is consistent with earlier findings that heterologous ras genes were highly lethal to protoplasts following direct DNA uptake. These effects could not be reversed by increasing exogenous or endogenous cytokinin levels. These effects were also independent of the v-Ha-ras mutations in functionally important regions of Ras proteins such as effector-binding and membrane-binding sites. Similarly, co-transformation with the genes encoding the Ras-negative regulators, GTPase-activating protein and neurofibromin did not affect the ras inhibitory effect, indicating that the mechanism of ras inhibition of plant cells is not related to normal ras cellular functions. This conclusion was supported by further studies in which ras gene expression was modified using various promoters and antisense constructs. The introduced ras sequences remained fully inhibitory regardless of which promoters (inducible or tissue-specific) or which orientations (sense or antisense) were tested. This strongly suggests that the ras DNA sequence itself, rather than the Ras protein or ras mRNA, is directly involved in the inhibitory effect. The mechanism underlying this novel phenomenon remains unknown. Introduced ras genes may inhibit plant cell growth by inducing co-suppression of unknown endogenous ras or ras-related genes, thereby leading to the arrest of cell growth.     

Modulation of postural tremors at the wrist by supramaximal electrical median nerve shocks in essential tremor, Parkinson's disease and normal subjects mimicking tremor

The response of postural wrist tremors to supramaximal median nerve stimulation was examined in patients with hereditary essential tremor (n = 10) and Parkinson's disease (n = 9), and in normal subjects mimicking wrist tremor (n = 8). The average frequency of on-going tremor was the same in all three groups. Supramaximal peripheral nerve shocks inhibited and then synchronised the rhythmic electromyographic (EMG) activity of all types of tremor. The duration of inhibition ranged from 90 to 210ms, varying inversely with the frequency of on-going tremor. There was no significant difference in mean duration of inhibition or in the timing of the first peak after stimulation on the average rectified EMG records between the three groups. The degree to which supramaximal peripheral nerve shocks could modulate the timing of rhythmic EMG bursts in the forearm flexor muscles was also quantified by deriving a resetting index. No significant difference in mean resetting index of the three groups was found. These results suggest that such studies cannot be used to differentiate between the common causes of postural wrist tremors.     

Retroviral gene transfer is inhibited by chondroitin sulfate proteoglycans/glycosaminoglycans in malignant pleural effusions

Gene therapy may be an important adjuvant for treating cancer in the pleural space. The initial results of retroviral gene transfer to cancer cells in malignant pleural effusions revealed that transduction was markedly inhibited, and studies to characterize the inhibitory factor(s) were performed. The inhibition was contained within the soluble, rather than cellular, components of the effusions and was demonstrated with amphotropic, gibbon ape leukemia virus, and vesicular stomatitis virus-glycoprotein pseudotyped retroviral vectors. After excluding complement proteins, a series of studies identified chondroitin sulfates (CSs) as the inhibitory substances. First, treatment of the effusions with mammalian hyaluronidase or chondroitinases, but not Streptomyces hyaluronidase, abolished the inhibitory activity. Second, addition of exogenous CS glycosaminoglycans mimicked the inhibition observed with pleural effusions. Third, immunoassays and biochemical analyses of malignant pleural effusion specimens revealed CS in relevant concentrations within pleural fluid. Fourth, proteoglycans/glycosaminoglycans isolated from the effusions inhibited retroviral gene transfer. Analyses of the mechanism of inhibition indicate that the chondroitin sulfates interact with vector in solution rather than at the target cell surface. These results suggest that drainage of the malignant pleural effusion, and perhaps enzymatic pretreatment of the pleural cavity, will be necessary for efficient retroviral vector mediated gene delivery to pleural metastases.