Mitochondrial encephalomyopathies: biochemical approach.

Thanks to recent advances in the molecular genetics of mitochondrial encephalomyopathies, we can now begin to correlate genetic lesions with biochemical defects. In the fatal infantile myopathy due to cytochrome c oxidase (COX) deficiency, an autosomal recessive condition, immunocytochemical studies have shown an isolated defect of subunit VIIa, which is 1 of the only 2 tissue-specific subunits of human COX. In muscle biopsies from patients with Kearns-Sayre syndrome, a multisystem disorder characterized by deletions of the mitochondrial DNA (mtDNA), the activities of all mitochondrial enzymes containing mtDNA-encoded subunits are decreased. The results of Northern analysis, in situ hybridization, and immunocytochemistry in muscle, and of mitochondrial protein synthesis in cultured fibroblasts suggest that partially deleted mtDNAs are transcribed but not translated, probably due to lack of indispensable tRNAs.     

Mitochondrial myopathy of childhood associated with depletion of mitochondrial DNA.

We have studied five children with mitochondrial myopathy manifesting within or soon after the first year of life. Muscle biopsies showed ragged-red fibers and decreased respiratory chain activity. All five patients had a severe decrease (2 to 34% of normal) in the amount of muscle mitochondrial DNA (mtDNA). The depletion of mtDNA correlated with absence of mtDNA-encoded translation products and with loss of cytochrome c oxidase enzyme activity in individual muscle fibers. This mitochondrial myopathy of childhood illustrates one phenotypic expression of a novel pathogenetic mechanism in mitochondrial diseases, the specific depletion of mtDNA in affected tissues.     

Comparison of Coccidioides immitis arthrospore, mycelium, and spherule cell walls, and influence of growth medium on mycelial cell wall composition.

Comparative lipid content, cell wall yield, neutral monosaccharide, glucosamine, and protein (amino acid) contents of arthrospores, mycelia, and spherules of Coccidioides immitis Cash were studied. Cellular lipid contents were found in the decreasing order: spherules, arthrospores, mycelia. Lipid content of mycelia did not reach the level of arthrospores or spherules even when mycelia were grown on relatively rich media. Cell wall yields of spherules were lower than for mycelia when grown on comparable media. Cell walls of arthrospores, mycelia, spherules, and spherule culture filtrate all contained 3-O-methylmannose, mannose, and glucose, but in varying amounts. Cell wall yield and cell wall glucose content increased in mycelia grown in increasingly rich media, whereas mannose content either decreased or remained constant.     

Lipoic (thioctic) acid increases brain energy availability and skeletal muscle performance as shown by in vivo31P-MRS in a patient with mitochondrial cytopathy

A woman affected by chronic progressive external ophthalmoplegia and muscle mitochondrial DNA deletion was studied by phosphorus magnetic resonance spectroscopy (³¹P-MRS) prior to and after 1 and 7 months of treatment with oral lipoic acid. Before treatment a decreased phosphocreatine (PCr) content was found in the occipital lobes, accompanied by normal inorganic phosphate (Pi) level and cytosolic pH. Based on these findings, we found a high cytosolic adenosine diphosphate concentration [ADP] and high relative rate of energy metabolism together with a low phosphorylation potential. Muscle MRS showed an abnormal work-energy cost transfer function and a low rate of PCr recovery during the post-exercise period. All of these findings indicated a deficit of mitochondrial function in both brain and muscle. Treatment with 600 mg lipoic acid daily for 1 month resulted in a 55% increase of brain [PCr], 72% increase of phosphorylation potential, and a decrease of calculated [ADP] and rate of energy metabolism. After 7 months of treatment MRS data and mitochondrial function had improved further. Treatment with lipoate also led to a 64% increase in the initial slope of the work-energy cost transfer function in the working calf muscle and worsened the rate of PCr resynthesis during recovery. The patient reported subjective improvement of general conditions and muscle performance after therapy. Our results indicate that treatment with lipoate caused a relevant increase in levels of energy available in brain and skeletal muscle during exercise.     

Urinmarkersysteme zur Diagnostik des Urothelkarzinoms

Cystoscopy and urinary cytology are standard tools in the diagnostics of urothelial cancer of the urinary bladder; however, cystoscopy is invasive and urinary cytology lacks accuracy for the diagnosis of low grade tumors. More recently several alternative urinary test systems were developed with the aim to make the diagnostics of urothelial tumors more reliable; however, in general all protein-based point of care test systems have a high rate of false positive test results, especially in patients with benign disorders. Fluorescence in situ hybridization, which is highly sensitive and specific, may be a reasonable supplement to the diagnostic spectrum in patients after instillation therapy or bladder replacement. Additionally, there are several new test systems which still need to be tested in large clinical studies with respect to diagnostic accuracy.     

Management von Harnröhrenstrikturen

For the diagnosis of urethral strictures it is of utmost importance to determine the exact position and length of the strictured area. The optimal method for this purpose is retrograde urethrography which can be combined with a voiding cystourethrography. Endoscopic treatment of urethral strictures is only reasonable for cases with short segment bulbar strictures (<1.5 cm) otherwise recurrence rates are very high. For long segment or recurrent strictures only open urethroplasty provides good results in terms of recurrence-free survival. In these open techniques care must be taken in early postoperative management to obtain the best results.     

Vesikoureteraler Reflux

Background

Vesico-ureteral reflux (VUR) is one of the most common urologic diseases in childhood. About every third child that presents with a urinary tract infection (UTI) has urinary reflux to the ureter or kidney. Demonstration of a backflow of urine into the ureters or kidneys proves vesicoureteral reflux. In unclear cases, a positioned instillation of contrast agent (PIC) cystogram might be performed and is able to prove vesico-ureteral reflux.

Objectives

Since low-grade VUR has a high probability of maturation and self-limitation, infants with VUR should be given prophylactic antibiotics during their first year of life, reevaluating the status of VUR after 12 months. The aim of any treatment is to prevent renal damage.

Therapy

The individual risk of renal scarring is decisive for the choice of adequate therapy. This risk is mainly dependent on reflux grade, age, and gender of the child as well as parental therapy adherence. In principle, therapeutic options include conservative as well as endoscopic or open surgical antireflux therapies.

Conclusion

Decisions on treatment should be made individually with parents taking into account all the findings available.

     

Definition of pulmonary embolism‐related death and classification of the cause of death in venous thromboembolism studies: Communication from the SSC of the ISTH

Pulmonary embolism (PE)‐related death is often a component of the primary outcome in venous thromboembolism (VTE) clinical studies. Definitions for PE‐related death vary widely, which may lead to biased risk estimates of clinical outcomes, thereby affecting both internal and external validity of study results. We here provide a standardized definition of PE‐related death and propose guidance for classification and reporting of the cause of death for clinical studies in VTE. The proposal was developed in a four‐step process, including a systematic review of definitions used for PE‐related death in previous studies, two subsequent surveys with VTE experts, and meetings held within the Scientific and Standardization Committee (SSC) working group until consensus on the proposal was reached. The proposed classification comprises three categories: Category A: PE‐related death, category B: undetermined cause of death, and category C: cause of death other than PE. Category A includes A1: autopsy‐confirmed PE in the absence of another more likely cause of death; A2: objectively confirmed PE before death in the absence of another more likely cause of death; and A3: PE is not objectively confirmed, but is most likely the main cause of death. Category B includes B1: cause of death is undetermined, despite available information; and B2: insufficient clinical information available to determine the cause of death. The use of the proposed definition will hopefully improve the accuracy of study outcomes, between‐study comparisons, meta‐analyses, and validity of future clinical VTE studies.