The chondrocyte channelome: A narrative review

Chondrocytes are the main cells in the extracellular matrix (ECM) of articular cartilage and possess a highly differentiated phenotype that is the hallmark of the unique physiological functions of this specialised load-bearing connective tissue. The plasma membrane of articular chondrocytes contains a rich and diverse complement of membrane proteins, known as the membranome, which defines the cell surface phenotype of the cells. The membranome is a key target of pharmacological agents and is important for chondrocyte function. It includes channels, transporters, enzymes, receptors, and anchors for intracellular, cytoskeletal and ECM proteins and other macromolecular complexes. The chondrocyte channelome is a sub-compartment of the membranome and includes a complete set of ion channels and porins expressed in these cells. Many of these are multi-functional proteins with “moonlighting” roles, serving as channels, receptors and signalling components of larger molecular assemblies. The aim of this review is to summarise our current knowledge of the fundamental aspects of the chondrocyte channelome, discuss its relevance to cartilage biology and highlight its possible role in the pathogenesis of osteoarthritis (OA). Excessive and inappropriate mechanical loads, an inflammatory micro-environment, alternative splicing of channel components or accumulation of basic calcium phosphate crystals can result in an altered chondrocyte channelome impairing its function. Alterations in Ca²⁺ signalling may lead to defective synthesis of ECM macromolecules and aggravated catabolic responses in chondrocytes, which is an important and relatively unexplored aspect of the complex and poorly understood mechanism of OA development.     

A new method for the termination of cervical pregnancy]

The authors described a 7 weeks old cervical pregnant case, whome was administered 250 mg methotrexate in infusion to eliminate the throphoblastic tissue. 3 days later the HCG was negative in the urine. After the dilatation of cervix by laminaria, the collapsed amniotic sac came from the cervix with minimal hemorrhage. They suggest the method is suitable to prevent the serious complications of cervical pregnancy.     

Contralateral approach to bilateral and ophthalmic aneurysms

In a previous survey, we found a high incidence of fatal rupture of an unclipped aneurysm in patients with multiple aneurysms. To deal with this problem, we introduced a more vigorous technique that accesses aneurysms previously considered unapproachable during one operating session. Attempts were made to clip middle cerebral and ophthalmic aneurysms contralateral to the operative exposure. We have successfully clipped contralateral aneurysms of the posterior communicating artery when bilateral aneurysms were present. We have also used this contralateral approach successfully with single ophthalmic and proximal carotid aneurysms that pointed medially. We review the cases of 39 patients with 43 intracranial aneurysms operated from the contralateral side and present the surgical technique in relation to the angiographic findings.     

Primary Radiotherapy of Stage IIA/B–IIIB Cervical Carcinoma

BACKGROUND: Comprehensive literature on cervical cancer demonstrates, even today, the need for optimization of the timing of external-beam radiotherapy (EBRT) and high-dose-rate brachytherapy (HDR-BT) in the treatment of stage IIA/B-IIIB cervical carcinoma. PATIENTS AND METHODS: 210 patients with carcinoma of the cervix were treated in the Municipal Center of Oncoradiology between January 1991 and December 1996 (FIGO IIA: n = 10, FIGO IIB: n = 113, and FIGO IIIB: n = 87). Two regimens were compared: sequential radiation therapy (SRT) with 4 x 8 Gy HDR-BT to point A followed by EBRT, and continuous radiation therapy (CRT) in which 5 x 6 Gy HDR-BT to point A, one session per week, was integrated into the EBRT. A total dose of 68-70 Gy to point A and 52-54 Gy to point B was given in EBRT with SRT, five fractions per week were applied. Four fractions per week were applied in CRT, i. e., no EBRT was performed on the day of HDR-BT. Total doses to points A and B were identical in both regimens. Overall treatment time (OTT) amounted to 56 days for SRT and 35 days for CRT. Median follow-up time was 3.4 (2.5-4.2) years. RESULTS: Progression-free 5-year-survival (PFS) was 71% in the CRT and 56% in the SRT group. Nevertheless, this difference was not statistically significant (p = 1.00), and the same was found in a subgroup analysis of the different tumor stages, showing, however, an unequivocal trend. Late bladder and rectal injuries occurred in 13% and 25%, respectively. Late rectal injuries were significantly more frequent with SRT than CRT (35 patients in the SRT and 18 patients in the CRT group; p = 0.037). This was due to the higher doses per fraction of HDR-BT in the SRT group. No difference was found regarding late bladder injuries (p = 0.837). CONCLUSION: For the patients included in this study, no advantage has been found so far in using CRT, i. e., shortening the OTT by weekly integration of HDR-BT into EBRT. Nevertheless, an obvious trend exists. The dose of 8 Gy per fraction of HDR-BT in the SRT regimen was obviously too high. To achieve a significant improvement in local control and disease-free survival (DFS) as well as overall survival (OS), the combination with modern chemotherapy regimens and regional deep hyperthermia may rather be the treatment option.     

Distribution and effects of pituitary adenylate cyclase activating peptide in cat and human lower oesophageal sphincter.

1. The localization, tissue concentrations, and effects of pituitary adenylate cyclase activating peptide (PACAP) 27 and 38 were investigated in cat and human lower oesophageal sphincter (LOS), and compared with those of vasoactive intestinal peptide (VIP) and helospectin. 2. PACAP-immunoreactive nerve structures were found in the cat and human LOS, with an abundance in the circular smooth muscle layer. PACAP 27-immunoreactivity was often co-localized with VIP-immunoreactivity. 3. In cat tissue, PACAP (PACAP 27 plus PACAP 38) concentrations were 50 fold lower than VIP concentrations; in human tissue they were 10 fold lower. 4. PACAP 27, PACAP 38, helospectin I, and VIP induced concentration-dependent relaxations in circular smooth muscle preparations from cat and human LOS. The order of potency was: VIP > helospectin I > or = PACAP 27 > PACAP 38. NG-nitro-L-arginine, scopolamine, or apamin, did not influence the relaxant effects of PACAP 27 or VIP. 5. In cat preparations, both cyclic AMP and cyclic GMP levels were increased after exposure to PACAP 27 and helospectin I, whereas exposure to VIP was followed by an increase in cyclic AMP levels only. In human preparations, there was an increase in cyclic AMP levels without any change in cyclic GMP levels. 6. These results suggest that in the cat and human LOS, PACAP 27 and VIP can occur within the same nerve structures. PACAP 27 has a potent relaxant action, but its functional importance has to be established.     

Neurotransmitter release evoked by α-latrotoxin in the smooth muscle of the female pig urethra

Neuronal regulation of smooth muscle tone in the female pig urethra has mainly been studied in vitro using electrical field stimulation (EFS) of nerves. Excitatory control is considered to be exerted by released noradrenaline, whereas inhibitory control is non-adrenergic non-cholinergic (NANC), and mediated by nitric oxide (NO), and an as yet unidentified agent. We investigated the functional and morphological effects of α-latrotoxin (αLTX), a spider neurotoxin believed to cause massive release of vesicle-stored neurotransmitters, on spontaneously developed urethral smooth muscle tone. The effects were compared to those of EFS and high potassium. In the presence of the NO-synthesis inhibitor N^ω-nitro-L-arginine (L-NOARG: 0.3 mM) both αLTX and EFS evoked contractions. After treatment with scopolamine and phentolamine, no contraction was observed, and under these conditions αLTX and EFS induced relaxation. At low frequencies (<12 Hz), the EFS-induced relaxations were rapid, whereas at higher frequencies (>12 Hz), they were biphasic, consisting of a rapid first phase followed by a more long-lasting second phase. L-NOARG abolished the relaxations at low frequencies, as well as the first phase of the biphasic relaxation. The second phase was not affected by treatment with L-NOARG, but 0.1 μM ω-conotoxin GVIA, blocker of N-type voltage-operated calcium- channels (VOCCs), markedly reduced or abolished the response. In the presence of L-NOARG or ω-conotoxin GVIA, the αLTX-induced relaxation was significantly decreased, and the combination of L-NOARG and ω-conotoxin GVIA further reduced or abolished the relaxation. In preparationstreated with tetrodotoxin or scorpion venom, believed to inactivate nerves by acting on sodium channels, αLTX and EFS had no effects. αLTX-induced relaxation was not associated with changes in cyclic GMP or cyclic AMP content. High (80 mM) potassium solution induced a triphasic response of the preparation. A transient relaxation was followed by a restoration of tone, and then by a persistent relaxation. The persistent relaxation was slightly reduced by scorpion venom or L-NOARG, but reduced by 50% by a combination of L-NOARG and ω-conotoxin GVIA. Ultrastructural analysis of the urethral circular smooth muscle layer revealed a moderate amount of nerve profiles supplying the smooth muscle. In control preparations, the nerve profiles contained both small synaptic vesicles and large dense core vesicles. αLTX caused a major loss of both types of vesicle. The present data suggest that αLTX has the ability to release not only adrenergic and cholinergic transmitters, but also NANC mediators of relaxation, including NO, from nerve terminals in the urethra. Received: 13 January 1997 / Accepted: 17 April 1997     

Effect of sleep on interictal spikes and distribution of sleep spindles on electrocorticography in children with focal epilepsy.

OBJECTIVE: To determine how sleep with central spindles alters the spatial distribution of interictal spike frequency in children with intractable focal seizures, and whether such children have spindles arising from the medial temporal region in addition to the frontal-central region. METHODS: Seventeen children (age: 7 months-17 years) were studied using extraoperative electrocorticography (ECoG). RESULTS: Overall spike frequency across the subdural electrodes was greater during sleep with central spindles compared to wakefulness. In 13 children showing at least 1 spike/min in an electrode, the spatial distribution of spike frequency was similar during wakefulness and sleep; in addition, the spike frequency was greater in the seizure onset zones compared to the non-onset areas, regardless of wakefulness or sleep. Spindles were identified in the medial temporal region during sleep with central spindles in all 17 children. CONCLUSION: Overall spike frequency may be increased by sleep with spindles, but the spatial distribution of spike frequency appears similar during wakefulness and sleep in children with intractable focal seizures. SIGNIFICANCE: Both awake and sleep ECoG may be useful to predict seizure onset zones in children with intractable focal epilepsy. Medial temporal spindles are present in some children with focal epilepsy.