Cellular mechanisms of motor control in the vibrissal system

In this article we discuss the experimental advantages that the vibrissal motor system offers for analysis of motor control and the specializations of this system related to the unique characteristics of whisker movements. Whisker movements are often rhythmic, fast, and bilateral. Movements of individual whiskers have simple characteristics, whereas, movements of the entire vibrissae array are complex and sophisticated. In the last few years, powerful methods for high precision tracking of whisker movements have become available. The whisker musculature is arranged to permit forward movements of individual whiskers and consists—depending on the species—mainly or exclusively of fast contracting, fast fatigable muscle fibers. Whisker motor neurons are located in the lateral facial nucleus and their cellular properties might contribute to the rhythmicity of whisking. Numerous structures provide input to the lateral facial nucleus, the most mysterious and important one being the putative central pattern generator (CPG). Although recent studies identified candidate structures for the CPG, the precise identity and the functional organization of this structure remains uncertain. The vibrissa motor cortex (VMC) is the largest motor representation in the rodent brain, and recent work has clarified its localization, subdivisions, cytoarchitectonics, and connectivity. Single-cell stimulation experiments in VMC allow determining the cellular basis of cortical motor control with unprecedented precision. The functional significance of whisker movements remains to be determined.     

Anterior Cruciate Ligament Reconstruction with Bone Patellar Tendon Bone Graft through a Mini Arthrotomy

Instability after rupture of anterior cruciate ligament (ACL) may lead to recurrent episodes of giving way, an increased risk of meniscal injury and premature degenerative changes. A total of 25 cases with ACL injuries were evaluated after reconstruction with bone patellar tendon bone graft through a mini-arthrotomy. All patients were male. Maximum number of patients were between 25-30 years of age (40%). The most common modality of injury was contact sports (44%). Most common complaint was instability of knee (100%). Average Lysholm score increased from pre-operative of 47 (27-75) to post-operative of 87 (68-95). Two patients (8%) had retropatellar pain. Moderate to severe graft site tenderness was present in 4 (21%). After an average follow up of one year three months, the results were comparable with the results of arthroscopic reconstruction.Key Words: Anterior cruciate ligament reconstruction, Mini arthrotomy     

Percutaneous angioplasty in clinical management of renovascular hypertension: initial and long-term results

Between January 1980 and July 1983, percutaneous transluminal angioplasty was attempted on 137 stenotic renal arteries in 100 patients. At termination of follow-up studies (3-39 months, mean of 16 months), 70% of those treated for hypertension had benefited from the procedure. Stenosis secondary to fibromuscular dysplasia responded better than stenosis from arteriosclerosis (85% and 65% of the patients, respectively). Benefit was minimal for those with stenosis of the renal artery ostium or renal insufficiency. Determining levels of renal vein renin before angioplasty is helpful in selecting patients; following angioplasty, this has considerable significance in predicting the success of the procedure.     

Synthesis and evaluation of conformationally restricted pyridino N‐alkylated nicotine analogs as nicotinic acetylcholine receptor antagonists

Previous work has shown that quaternization of the pyridine‐N atom of S‐(–)‐nicotine (NIC) affords compounds such as N‐n‐octylnicotinium iodide (NONI) and N‐n‐decylnicotinium iodide (NDNI) that act as competitive nicotinic acetylcholine receptor (nAChR) antagonists at α3β2* and α4β2* subtypes, respectively. To ascertain the rotameric preference about the C3‐C2′ bond of NONI and NDNI for interaction with several nAChR subtypes, two classes of bridged analogs representing extreme rotameric conformations (syn and anti) of NONI and NDNI were synthesized. NIC‐evoked [³H]dopamine ([³H]DA) release from superfused rat striatal slices was used to determine the activity of the analogs at the α3β2* nAChR. [³H]NIC and [³H]methyllycaconitine ([³H]MLA) binding to rat brain membranes were used to determine affinity for α4β2* and α7* nAChRs, respectively. With the exception of BCDD (IC₅₀ value = 1,580 nM), all analogs potently and selectively inhibited NIC‐evoked [³H]DA release (IC₅₀ values = 30–660 nM), indicating antagonism of α3β2* nAChRs. None of the analogs inhibited either [³H]NIC or [³H]MLA binding, indicating a lack of interaction with α4β2* and α7* nAChR subtypes. Interestingly, the C_{10 N}‐alkyl chain analogs, ACD and BCD, had negligible affinity for the α4β2* subtype compared to the high affinity exhibited by NDNI, suggesting that the α4β2* subtype does not recognize the unique stereochemistry of these conformationally restricted analogs. Thus, conformational restriction of N‐n‐alkylnicotinium iodides eliminated inhibitory activity at α4β2* nAChRs, but more importantly afforded high affinity and selectivity for α3β2* nAChRs. Conformational restriction of N‐n‐alkyl analogs of NIC appears to be a viable approach for the development of α3β2*‐selective nAChR antagonists. Drug Dev. Res. 55:172–186, 2002. © 2002 Wiley‐Liss, Inc.     

Indications for breast imaging in women under age 35 years

To determine appropriate indications for breast imaging in young women, the authors correlated patient histories with mammographic and/or sonographic findings and biopsy or follow-up results for 625 patients aged 13-34 years. The only important indications were a palpable mass and suspicion of an abscess. Of the 335 studies performed for evaluation of a palpable mass, 184 (55%) were normal, 28 (8%) were compatible with benign disease, and 123 (37%) were suggestive of malignancy. Biopsies were performed in 73 patients; the findings were benign in 67 cases, and carcinoma was found in six. Imaging studies were considered helpful in four of the 15 cases of suspected abscess, in that the studies established the presence and extent of an abscess. Studies in 275 women were performed for a variety of other indications. The findings were normal in 239 (87%) studies, benign in 21 (8%), and suggestive of malignancy in 15 (5%); there were no known carcinomas in any of the patients. Women with the "low-yield" indications identified in this study should be followed up clinically rather than referred for imaging studies.