Magnetic resonance imaging of foot and ankle trauma

MRI is a useful diagnostic tool in the assessment of traumatic lesions of the foot and ankle. It is especially useful in demonstrating acute and chronic tendon and ligament injuries. Subtle fractures, including osteochondral, nondisplaced, and stress fractures, are well shown with MRI but may be difficult to detect on radiographs. A bone scan may also be used to detect these fractures; however, with MRI the fracture extent may be determined. MRI is also useful in diagnosing complication of trauma, such as ischemic necrosis and bone and soft-tissue infections.     

Branched, struvite calculus and clear cell carcinoma in same kidney. Rare condition with significant implications for management

The concomitant existence of a branched (partial staghorn) calculus and clear cell carcinoma (hypernephroma) in the same kidney is rare. Herein, we report the eighth such case in the world literature, and to our knowledge, the first patient with a parenchymal tumor identified preoperatively. In all of the previous 7 cases, the calculus was managed with open renal exploration, and only at the time of surgery was the incidental renal cell carcinoma identified; the surgical procedure was modified accordingly. With open surgery no longer the cornerstone of therapy for renal calculi, it is imperative that the kidney be evaluated in a meticulous and compulsive manner prior to extracorporeal shock wave lithotripsy (ESWL) or percutaneous nephrolithotomy (PNL). The finding of a coexisting renal cell carcinoma will radically alter the patient's treatment.     

Flip side of synaptic plasticity: Long-term depression mechanisms in the hippocampus

There is growing interest in the phenomenon of long-term depression (LTD) of synaptic efficacy that, together with long-term potentiation (LTP), is a putative information storage mechanism in mammalian brain. In neural network models, multiple learning rules have been used for LTD induction. Similarly, in neurophysiological studies of hippocampal synaptic plasticity, a variety of activity patterns have been effective at inducing LTD, although experimental paradigms are still being optimized. In this review the authors summarize the major experimental paradigms and compare what is known about the mechanisms of LTD induction. Although all paradigms appear to initiate a cascade of events leading to an elevated level of Ca²⁺ postsynaptically, the extent to which these paradigms involve common expression mechanisms has not yet been tested. The authors discuss several critical experiments that would address this latter issue. Numerous questions about the properties and mechanisms of LTD(s) in the hippocampus remain to be answered, but it is clear that LTD has finally arrived, and will soon be attracting attention equal to its flip side, LTP. © 1994 Wiley-Liss, Inc.     

Experimental cryptorchidism in the adult mouse: I. Qualitative and quantitative light microscopic morphology

Morphologic changes in the testes of adult mice after experimentally induced cryptorchidism were studied by light microscopy and stereology. Increasing duration of cryptorchidism resulted in a gradual decrease in the volume of seminiferous tubules per testis, and this was associated with germ cell degeneration. The volumes of Sertoli cell lipid droplets increased, and dilations of the intercellular space between the Sertoli cell junctions was observed in the cryptorchid testis. The luminal volume of the seminiferous tubule was reduced by 50% after 28 days of cryptorchidism. However, the volumes of intertubular tissue and Leydig cells in control and cryptorchid testes were not significantly different. Leydig cell number per testis increased, and the average volume of a Leydig cell decreased gradually with the progression of the cryptorchid state. The volume of the connective tissue cells in the intertubular area increased, but no significant volume change was observed in the volume of intertubular macrophages. After 28 days, the cryptorchid testis contained a significantly increased volume of blood vessels and a reduced volume of lymphatic space per testis. These observations clearly demonstrate that, although the mouse is a species closely related to the rat, the morphologic changes that occur in the Leydig cell population after induction of experimental cryptorchidism in this species is different.     

Zinc deficiency and hyperprolactinaemia are not reversible causes of sexual dysfunction in uraemia

We selected a group of male dialysis patients complaining of sexual dysfunction in whom penile vascular insufficiency and drug-induced impotence had been excluded. Monitoring of nocturnal penile tumescence was used to confirm organic disturbance. Patients with normal serum prolactin concentrations (n = 18) had significantly lower serum zinc values than normal controls (P less than 0.001) and were entered in a 6-month double-blind study comparing oral zinc acetate with placebo. Patients with elevated prolactin concentrations (n = 8) were entered in a 3-month double-blind crossover study comparing oral pergolide mesylate with placebo. In the zinc study, serum zinc concentrations increased (P less than 0.05) in the zinc-treated but not the placebo-treated group. One of nine patients receiving zinc reported improved sexual function, as did two of nine patients receiving placebo. There were no significant changes in sperm counts, nocturnal penile tumescence, testosterone, sex hormone binding globulin or gonadotrophin concentrations in either treatment group. In the pergolide study, serum prolactin values decreased (P less than 0.01) in the pergolide but not in the placebo treatment period. One patient reported improved sexual function during the pergolide treatment period and two during the placebo period. There were no significant changes in sperm counts, nocturnal penile tumescence, testosterone, sex hormone binding globulin or gonadotrophin concentrations after pergolide. These studies show no benefit of zinc or pergolide compared with placebo in the treatment of uraemic impotence.     

Serum and peritoneal dialysate thyroid hormone levels in patients on continuous ambulatory peritoneal dialysis

Thyroid function tests were performed on 16 clinically euthyroid patients with end-stage renal failure undergoing regular haemodialysis or continuous ambulatory peritoneal dialysis and compared with 8 healthy subjects. The patient groups were carefully matched, especially regarding relative duration of dialysis (mean of 24 months). Total serum thyroxine, total triiodothyronine, free thyroxine, free triiodothyronine and reverse triiodothyronine were significantly lower in both patient groups than control. The thyrothrophin response to the standard thyrotrophin-releasing hormone test was delayed and blunted. Using a novel concentration technique we measured loss of T4 in peritoneal dialysate effluent and found it to be approximately 10% of daily thyroidal T4 release.     

Delayed Nociceptive Response Following Cold-Water Swim in the Formalin Test: Possible Mechanisms of Action

Exposure of animals to aversive events produces stress-induced analgesia. A common method of producing stress in animals is the cold-water swim (CWS). The present series of experiments examines the effect of CWS on tonic pain, as measured by the formalin test, and explores possible mechanisms of action. Experiment 1 demonstrates that a 3.5-min swim in 2°C water produces a delayed nociceptive response (DNR), characterized by a prolonged period of no formalin responding which then begins and continues during the time when control animals, which have not received the CWS, are finished responding. The delayed response begins at 50–60 min postformalin injection, peaks at 80 min, and is still present at 120 min. Experiment 2 indicates that paw temperature effects are not responsible for the DNR, although core body temperature effects are a possible mechanism. However, systematic delays in the formalin injection following the CWS (Experiment 3) drastically altered the DNR even though core body temperature remained unchanged, suggesting that a decrease of core body temperature is insufficient to account for the DNR. Experiment 4 demonstrates that the NMDA antagonist MK-801 administered prior to the CWS dramatically reduces the DNR. The present experiment is the first study that reports a delay as long as 60 min in pain responding. It is concluded that the delayed response to formalin injection is the result of complex interactions involving peripheral mechanisms and central neuronal plasticity in which activity initiated by a noxious input persists after the cessation of the input as a consequence of a stressful event such as the cold-water swim.