Models of benthic bipedalism.

Walking is a common bipedal and quadrupedal gait and is often associated with terrestrial and aquatic organisms. Inspired by recent evidence of the neural underpinnings of primitive aquatic walking in the little skate Leucoraja erinacea, we introduce a theoretical model of aquatic walking that reveals robust and efficient gaits with modest requirements for body morphology and control. The model predicts undulatory behaviour of the system body with a regular foot placement pattern, which is also observed in the animal, and additionally predicts the existence of gait bistability between two states, one with a large energetic cost for locomotion and another associated with almost no energetic cost. We show that these can be discovered using a simple reinforcement learning scheme. To test these theoretical frameworks, we built a bipedal robot and show that its behaviours are similar to those of our minimal model: its gait is also periodic and exhibits bistability, with a low efficiency mode separated from a high efficiency mode by a 'jump' transition. Overall, our study highlights the physical constraints on the evolution of walking and provides a guide for the design of efficient biomimetic robots.

Structural allograft and primary press-fit cup for severe acetabular deficiency. A minimum 6-year follow-up study.

Between October 1992 and December 1996, 23 patients with pelvic bone stock deficiency involving major columns underwent revision surgery with a cementless press-fit cup and a structural bone graft. Twenty cases were followed up for a minimum of 6 (average 7.6, range 6-11) years. Three cups were revised: one for aseptic loosening, one for septic loosening, and one for recurrent dislocation. At latest follow-up, the average Merle d'Aubigne hip score improved from 10.9 to 16.2; four hips were rated excellent, seven very good, three good, two fair, and one poor. All cups were stable; the grafts were integrated and anatomy was restored. The Kaplan-Meier cumulative probability of not having revision for loosening at 11 years, predicted a survival rate of 84.4%. We are confident that these results are satisfactory for a very demanding procedure.

Intrapelvic migration of the prosthetic acetabular component.

The authors propose a preoperative evaluation protocol for cases of dislocation of the prosthetic cup complicated by intrapelvic migration, obtained by studying 20 cases of prosthetic loosening with protrusion of the acetabular component in the pelvis, treated by reimplantation or explantation. In all of the patients, accurate preoperative planning was carried out, because of the considerable frequency of dislocation, compression or damage to the vascular and nervous structures deriving from migration inside the pelvis of the acetabular component. The authors suggest that in all cases of acetabular loosening evaluation involve standard X-rays, bone scan with technethium99 and with marked granulocytes, CT scan. When the cup protrudes in the pelvis, prior to surgery, CT scan with contrast medium will be required, and if the risk of vascular involvement exists, angiography should also be carried out.

Fractures and dislocations of the lower cervical spine: surgical treatment. A review of 83 cases.

The authors examine 83 consecutive cases of fracture and dislocation of the lower cervical spine submitted to surgery over a period of 5 years. Sixty-five patients were monitored with minimum 5-months follow-up, 5 died, 13 could not be traced. Lesions were classified based on the method proposed by Argenson3 with the purpose of identifying guidelines for surgical treatment. Thus, different methods are proposed based on the type of lesion and on any neurologic deficit. Intersomatic fusion with anterior approach is the method of choice in most lesions. The exception to this is monoarticular dislocations that cannot be reduced, so that reduction by posterior approach associated with discectomy and anterior fusion are recommended. Circumferential fusion is proposed for traumatic spondylolistheses, complete dislocations with unsatisfactory anterior reduction, in lesions in flexion-extension and rotation associated with complete spinal cord injury, in order to favor functional rehabilitation free from ortheses. The need to review many cases of traumatic lesions of the lower cervical spine (LCS) collected over a relatively short period of time derives from the need to identify guidelines that will help the surgeon in his or her choice of the type of surgery to perform on the patient with emergency injury. The basic premise, as for other sites of traumatic injury, resides in an efficient classification (corresponding to the anatomic injury and of immediate and intuitive application) to which options for treatment may be related. In particular, an evaluation of the type of approach (anterior, posterior, combined) and of the sequence of surgical stages is essential to obtaining effective results with an acceptable complication rate. Finally, treatment must be definitive, and in cases of severe spinal cord injury it must allow for rapid rehabilitation and freedom from the use of ortheses.

Hip arthroplasty after femoral osteotomy.

Osteotomy of the proximal femur is performed to treat numerous hip pathologies in order to improve the load axis of the coxofemoral joint, thus improving coverage of the femoral head; despite this, arthrosis-related pathology may progress, and this nearly always results in hip arthroplasty. Many authors report that the time interval between osteotomy and arthroplasty is approximately 5 to 10 years. It is the purpose of this study to evaluate the complications and the clinical and radiographic results of hip arthroplasty performed after proximal femoral osteotomy, comparing them with a control group for hip arthroplasty without previous osteotomy.

High prevalence of asymptomatic hypothyroidism and hyperthyroidism in hospitalized elderly females.

To investigate the prevalence of asymptomatic hypothyroidism and hyperthyroidism in hospitalized people, we performed thyroid function tests on a group of 2545 elderly patients consecutively observed in a General Hospital in Rome, during a six year period. The rate of asymptomatic hypothyroidism was as high as 0.71% in female patients and only 0.20% in male patients. In asymptomatic hyperthyroid subjects the prevalence rate was 0.58% in females and 0.20% in males. On the whole, prevalence rate of asymptomatic thyropathies resulted 0.94%, showing a clear difference in sex (women 1.29% and men 0.40%). The asymptomatic thyropathies screening of hospitalized elderly women may result in a very low cost diagnosis of many new cases of hypothyroidism and hyperthyroidism.

Does it exist also a "late" post-surgical hypoparathyroidism?

Hypoparathyroidism following neck surgery, mainly thyroidectomy, is not a rare event, well known since many years. Post-surgical hypoparathyroidism may occur in form of two clinical syndromes of different etiology and prognosis. The first disease is a transitory hypoparathyroidism that might spontaneously recover within a few weeks or months. The second disease is a permanent hypoparathyroidism needing a definitive opoterapic treatment. Anyhow in both cases, hypocalcemic symptoms begin always within a short time from surgery, usually after an asymptomatic period elapsing from days to months. Only few cases of hypoparathyroidism clinically conclamate after many years from surgery have been reported. Description of a patient with hypoparathyroidism that became clinically evident thirty years after the thyroid surgery is herewith described. Our findings and review of a few cases reported by medical literature, can suggest a third form of post-surgical hypoparathyroidism with the distinctive feature of a very late beginning, probably following a long period of a latent parathyroid insufficiency.

[Risk indices in stroke and cerebral TIA: a retrospective analysis in hospitalized patients]. / Indici di rischio nello stroke e nel TIA cerebrale: analisi retrospettiva in pazienti ospedalizzati.

In a group of 936 patients admitted to our Hospital for ischemic stroke and transient ischemic attack we studied the association with three diseases which have been identified as risk factors by several international trials: diabetes mellitus, hypertension, atrial fibrillation. We found diabetes mellitus in 24.1% of our patients, hypertension in 44.3%, atrial fibrillation in 17%. We also found a significative difference between men and women for hypertension and atrial fibrillation; respectively 39.6% versus 49.1% (p < 0.01), and 11.4% versus 22.6% (p < 0.01).

A new case of apo C-II deficiency with a nonsense mutation in the apo C-II gene.

The apo C-II gene from a patient with apo C-II deficiency has been sequenced after amplification by the polymerase chain reaction (PCR). The sequence analysis revealed a substitution of adenosine for cytosine at position 3,002 in exon 3, leading to the introduction of a premature stop codon (TAA) at a position corresponding to aminoacid 37 of mature apo C-II. This mutation creates a new Rsa I restriction enzyme site in the apo C-II gene. Amplification of DNA from family members by PCR and digestion with Rsa I established that the patient is a true homozygote for this mutation. The same nucleotide has been substituted for the mutation apo C-IIPadova and apo C-IIBari previously described in two kindreds from Italy. From these data we speculate that base pair 3,002 in the apo C-II gene may represent a hot spot for mutation.

Follow up and surgical considerations on a series of patients operated on for non tumoral aqueductal stenosis.

A series of 90 patients operated on between 1966 and 1983 in the Neurosurgical Division of USL 10/D (Florence) for non tumoral aqueductal stenosis is presented. The Authors discuss the different of shunts used and the follow up which is favourable in patients operated on with an early diagnosis.