Verhandlungen Ärztlicher Gesellschaften

Ohne Zusammenfassung     

Clinical Observations on Chlorothiazide and Rauwolfia in Treatment of Essential Hypertension

To evaluate the antihypertensive effect of a combination of chlorothiazide and Rauwolfia, 26 patients were given chlorothiazide alone for two months and 24 were given Rauwolfia alone for the same period; then 18 patients (10 from the first group and eight from the second) were given both drugs for two months.

Chlorothiazide alone proved to be an effective antihypertensive agent in 35 per cent of patients with mild to moderate hypertension. The number of cases in which the blood pressure decreased to normotensive levels increased when Rauwolfia was added. Results of combined therapy were better when chlorothiazide rather than Rauwolfia was given alone first.     

Efficient insertion of genes into the mouse germ line via retroviral vectors.

We present a general strategy for the efficient insertion of recombinant retroviral vector DNA into the mouse germ line via infection of preimplantation mouse embryos. Transgenic mice were generated that harbor a replication-competent recombinant retrovirus (delta Mo + Py M-MuLV) that lacks the Moloney murine leukemia virus (M-MuLV)-type enhancer sequence in the long terminal repeat (LTR). Instead, the LTR contains an enhancer element that permits polyoma virus F101 to grow in undifferentiated F9 embryonal carcinoma cells. Expression studies in different tissues of animals transgenic for delta Mo + Py M-MuLV indicate possibilities to target and modulate expression of retroviral recombinants in mice via their LTR enhancer sequences. In addition, 16 transgenic mice were generated that harbor proviral DNA of a defective recombinant retrovirus carrying a mutant dihydrofolate reductase gene.     

New approach to gridding using regularization and estimation theory.

When sampling under time-varying gradients, data is acquired over a non-equally spaced grid in k-space. The most computationally efficient method of reconstruction is first to interpolate the data onto a Cartesian grid, enabling the subsequent use of the inverse fast Fourier transform (IFFT). The most commonly used interpolation technique is called gridding, and is comprised of four steps: precompensation, convolution with a Kaiser-Bessel window, IFFT, and postcompensation. Recently, the author introduced a new gridding method called Block Uniform ReSampling (BURS), which is both optimal and efficient. The interpolation coefficients are computed by solving a set of linear equations using singular value decomposition (SVD). BURS requires neither the pre- nor the postcompensation steps, and resamples onto an n x n grid rather than the 2n x 2n matrix required by conventional gridding. This significantly decreases the computational complexity. Several authors have reported that although the BURS algorithm is very accurate, it is also sensitive to noise. As a consequence, even in the presence of a low level of measurement noise, the resulting image is often highly contaminated with noise. In this work, the origin of the noise sensitivity is traced back to the potentially ill-posed matrix inversion performed by BURS. Two approaches to the solution are presented. The first uses regularization theory to stabilize the inversion process. The second formulates the interpolation as an estimation problem, and employs estimation theory for the solution. The new algorithm, called rBURS, contains a regularization parameter, which is used to trade off the accuracy of the result against the signal-to-noise ratio (SNR). The results of the new method are compared with those obtained using conventional gridding via simulations. For the SNR performance of conventional gridding, it is shown that the rBURS algorithm exhibits equal or better accuracy. This is achieved at a decreased computational cost compared to conventional gridding.     

Survival of trauma patients with coma and bilateral fixed dilated pupils

Background

Survival of patients with severe trauma presenting with Glasgow Coma Score (GCS) 3 and bilateral fixed dilated pupils is uncertain. Pre-hospital management of these patients affects the true measurement of the GCS and other factors may affect pupillary status.

Patients and methods

A retrospective review was undertaken of all patients who were classified GCS 3 and had bilateral fixed dilated pupils on admission to a Level 1 Adult Trauma Centre between July 2001 and March 2005. Pre-hospital assessment, hospital interventions and outcomes were determined.

Results

Ninety-three patients fulfilled the criteria for inclusion into the study. There were 6 survivors who were all less than 28 years of age, had at least one GCS score above 3 in the pre-hospital phase and were more likely to have had an evacuable mass lesion on CT brain scan and undergo craniotomy. Of the 6 surviving patients, none had significant thoracoabdominal injuries. Four of the survivors had Glasgow Outcome Score (GOS) of 4 or 5. Time to hospital, mechanism of injury and pre-hospital haemodynamic parameters had no significant effect on survival. Of the 57 patients who were GCS 3 at the scene of the accident, post-basic resuscitation and on admission, none survived.

Conclusion

Pre-hospital GCS scores, prior to the effects of intubation, sedation and paralysis should be given more attention when assessing prognosis in patients who are GCS 3 on admission. Trauma patients with GCS 3 persisting from the scene with bilaterally fixed dilated pupils have no appreciable chance of survival. Further interventions such as ICU admission and surgery may not be warranted. Physicians may need to consider stopping treatment and discussing organ donation.     

Design of adiabatic selective pulses using optimal control theory

Optimal control theory has been applied in the past for the design of RF pulses for selective excitation. This was the outcome of having established the controllability of the MR spin system for the selective excitation problem. “Minimum distance” was the main formulation used for the solution. Because of their robust behavior in the presence of inhomogeneous RF fields, adiabatic pulses play an important role in spin inversion and excitation. In this study, we present a method for incorporating adiabaticity into the optimal control problem by enhancing the cost functional with an appropriate term. Two different types of adiabatic terms are proposed. Furthermore, two methods are used to solve the optimal control problem, namely the Hamiltonian approach and the solution by mathematical programming. Design examples include both a frequency selective pulse for performing fat suppression by inversion and a regular inversion pulse. It is shown that, in the course of optimization, the pulse designer can trade-off slice resolution against pulse adiabaticity.