Evolutionary aspects of positioning and identification of vertebrate limbs

Emerging developmental studies contribute to our understanding of vertebrate evolution because changes in the developmental process and the genes responsible for such changes provide a unique way for evaluating the evolution of morphology. Endoskeletal limbs, the locomotor organs that are unique to vertebrates, are a popular model system in the fields of palaeontology and phylogeny because their structure is highly visible and their bony pattern is easily preserved in the fossil records. Similarly, limb development has long served as an excellent model system for studying vertebrate pattern formation. In this review, the evolution of vertebrate limb development is examined in the light of the latest knowledge, viewpoints and hypotheses.     

Impact of aging on penile hemodynamics in men responding normally to prostaglandin injection: A power Doppler study

AIM: Hemodynamic changes with aging in the penile arterial circulation, including the helicine arteries, were evaluated with power Doppler imaging in erectile dysfunction patients with a normal response to prostaglandin injection. METHODS: In 36 patients with erectile dysfunction and no definite vascular risk factors, 72 corpora were examined using power Doppler imaging. Patients were classified by age: younger than 40 years, from 40 to 49, or 50 and older. Hemodynamic variables in the cavernous arteries, helicine arteries and dorsal arteries were measured after intracavernous injection of prostaglandin E1 (20 microg). RESULTS: All cavernous arteries had a maximum peak systolic velocity of greater than 35 cm/s and a minimum end-diastolic velocity of less than 0 cm/s. Mean peak systolic velocity in the cavernous artery differed between groups (P = 0.016), especially between the younger than 40 age group and the 40-49 age group. Peak systolic velocity correlated negatively with age (P = 0.0048). In the helicine arteries and dorsal arteries, peak systolic velocity did not differ between groups and showed no correlation with age. End-diastolic velocity, resistance index and acceleration time did not differ between groups, or correlate with age for any artery. CONCLUSIONS: Hemodynamic change with aging occurs predominantly in the cavernous arteries, where peak systolic velocity decreases. The arterial circulation beyond the cavernous arteries, including the helicine arteries, as well as veno-occlusive mechanisms, may have an important role in maintaining erectile function in aging.     

Giant retroperitoneal liposarcoma

Liposarcomas are one of the most common soft tissue sarcomas of adulthood. Liposarcomas are remarkable because of their frequently large size. We report a case with an extremely large dedifferentiated liposarcoma that weighed 18 kg. Although it was capsulated and could be excised en bloc, the patient suffered a relapse 9 months later and died 1 year after the operation.     

Topographic mapping of electroencephalography coherence in hypnagogic state

Abstract The present study examined the topographic characteristics of hypnagogic electroencephalography (EEG), using topographic mapping of EEG power and coherence corresponding to nine EEG stages (Hori's hypnagogic EEG stages). EEG stages 1 and 2, the EEG stages 3–8, and the EEG stage 9 each correspond with standard sleep stage W, 1 and 2, respectively. The dominant topographic components of delta and theta activities increased clearly from the vertex sharp-wave stage (the EEG stages 6 and 7) in the anterior-central areas. The dominant topographic component of alpha 3 activities increased clearly from the EEG stage 9 in the anterior-central areas. The dominant topographic component of sigma activities increased clearly from the EEG stage 8 in the central-parietal area. These results suggested basic sleep process might start before the onset of sleep stage 2 or of the manually scored spindles.     

Laparoscopic prediction of hepatocellular carcinoma in cirrhosis patients

Previously, laparoscopic studies have not been successful in predicting the occurrence of small hepatocellular carcinoma because cirrhotic patients had not been separated into groups of those who developed small hepatocellular carcinoma under 3 cm in diameter, and those who did not. Retrospective examination with better separation of the two groups gave improved results. Of the 26 laparoscopic findings, only the presence of large complex regenerative nodules was closely associated with the occurrence of subclinical small hepatocellular carcinoma. The study of other cirrhotic patients with and without large complex regenerative nodules gave a cumulative hepatocellular carcinoma occurrence rate of 73% for patients who had these nodules by the third year after laparoscopy. In contrast, the rate for patients without such nodules was 6%, showing a significant difference (P < 0.05) between the two groups. We concluded that the laparoscopic finding of large complex regenerative nodules of liver cirrhosis can be used to predict the occurrence, or a complication, of subclinical small hepatocellular carcinoma.     

Pathogenesis of distal renal tubular acidosis (incomplete form) in cirrhosis: Normal urinary Pco2 after bicarbonate loading

In liver cirrhosis, an associated defect in urinary acidification is well known but its pathophysiologic nature is not well defined. Recent studies suggest that the urine P co₂ during maximal alkalinization of the urine is an adequate index of distal hydrogen ion secretion. To evaluate the nature of distal renal tubular acidosis (distal RTA) in cirrhosis, the urine minus blood P co₂ gradient [(U – B) P co₂] in alkaline urine was determined in four patients with cirrhosis and distal RTA, and compared with that in four patients without distal RTA (control subjects), as well as with that in one patient with Sjögren's syndrome and distal RTA (subject with impaired distal acidification). As expected, the (U – B) P co₂ after sodium bicarbonate loading was low (10.6 mmHg) in the subjects with impaired distal acidification and normal (32.5 mmHg, s.e.m. = 4.8) in control subjects. By contrast, all four patients with cirrhosis and distal RTA were able to achieve a normal (U – B) P co₂ gradient (33.8 mmHg, s.e.m. = 4.0) after sodium bicarbonate loading, even in the presence of the defect in urinary acidification under acid loading. These results suggest that the pathophysiology of the urinary acidification defect in liver cirrhosis is distinct from that in ordinary distal RTA; the latter signifies a defect in H⁺ secretion (secretory or voltage-dependent RTA), whereas, in cirrhosis, an increased permeability for H⁺ may cause the inability to acidify the urine.     

CT examination of the head of the Baikal seal (Phoca sibirica)

We carried out a computerised tomographic (CT) examination to elucidate the modifications in the head related to orbital enlargement in the Baikal seal. Transverse CT images showed that (1) the external frontal contours and the frontal sinuses are compressed medially and ventrally by the orbital enlargement; (2) the caudal part of the nasal cavity and nasopharynx are compacted ventrally; and (3) the cranial cavity is displaced caudally. The neurocranium is obviously separated from the facial part in the transverse plane at the caudal region of the orbit. The disposition of the mandible, zygomatic arch, temporal bone, and the masseter, temporal, digastric and pterygoid muscles is changed by the enlarged orbit in the 3-dimensional reorganisation of the head in this species. It is suggested that adaptation for the Lake Baikal environment primarily resulted in orbital enlargement, and that the altered orbital design may subsequently have influenced the form and function of the masticatory and respiratory system.     

Chemical synthesis of dendrotoxin-I: revision of the reported structure

Dendrotoxin I (DTX-I) is a 60-residue peptide from the venom of the black mamba snake Dendroaspis polylepis, which binds to neuronal K⁺ channels. The structure reported previously for DTX-I was synthesized for the first time by a solution procedure. The synthetic product was confirmed to have the correct primary and disulfide structure determined by peptide mapping, sequence analysis and mass measurements. Comparison of synthetic DTX-I with the natural one by high-performance liquid chromatography and capillary zone electrophoresis, as well as by sequence analysis, revealed that the Asn residue at position 12 in the synthetic peptide was Asp in the natural product. Synthesis of DTX-I with Asp at position 12 gave a peptide identical with the natural product in all aspects. NMR analysis of synthetic [Asn¹²]. - and [Asp¹²]. -DTX-I also supported our findings that the Asn residue at position 12 in the DTX-I molecule should be revised as Asp. [Asn¹²]. - and [Asp¹²]. -DTX-I had very similar binding affinities when tested against radiolabeled dendrotoxin binding to rat brain synaptosomal membranes. © Munksgaard 1998.