PI3K-dependent actions of insulin and IGF-I on seminiferous tubules from immature rats

There is clear evidence that insulin and insulin-like growth factor I (IGF-I) are crucial for the normal metabolism and development of Sertoli cells. However, the mechanisms of insulin regulatory signaling remain unknown in these cells, especially during the immature period. The aim of this study was to investigate the electrophysiological effects of insulin and the effects of insulin and IGF-I on calcium uptake, amino acid, and glucose transport in whole seminiferous tubules from 12-day-old rats, as well as the involvement of PI3K/Akt signaling pathway in these effects. Insulin produces a depolarizing effect on the membrane potential of Sertoli cells in seminiferous tubules within 180 s. This effect was nullified by verapamil, an L-type voltage-dependent calcium channel blocker, therefore demonstrating a calcium-dependent depolarizing effect. Both insulin and IGF-I stimulate calcium uptake, amino acid, and glucose transport in whole testes from 12-day-old rats. These stimulatory effects of insulin and IGF-I on calcium uptake and amino acid and glucose transport on testicular tissue were nullified by wortmannin, which demonstrates the involvement of the PI3K/Akt signaling pathway in these hormonal effects.     

The prevalence and CT appearance of the levator claviculae muscle: a normal variant not to be mistaken for an abnormality.

BACKGROUND AND PURPOSE: The levator claviculae muscle is an infrequently recognized variant in humans, occurring in 2% to 3% of the population, and has rarely been reported in the radiologic or anatomic literature. The importance of this muscle to radiologists is in distinguishing it from an abnormality; most commonly, cervical adenopathy. After discovering this muscle on the CT scans of two patients during routine clinical examinations, we conducted a study to determine the prevalence and appearance of the muscle on CT studies. METHODS: We evaluated 300 CT scans that adequately depicted the expected location of the muscle. The most superior level in which the muscle could be identified and the apparent location of insertion on the clavicle were recorded for all subjects in whom the muscle was detected. RESULTS: Seven levator claviculae muscles were identified in six subjects (2%). It was bilateral in one, on the left in four, and on the right in one. It was identified up to the level of the transverse process of C3 in all cases. The insertion was the middle third of the clavicle for two muscles and the lateral third of the clavicle for the remaining five muscles. CONCLUSION: Because the levator claviculae muscle will most likely be encountered during a radiologist's career, it is important to recognize this muscle as a variant and not as an abnormality.     

Chronic progressive renal lesions induced by lithium

New Zealand white rabbits, eight fed lithium (Li) (50 to 250 mmole LiCl/kg food) and seven controls (C) had sequential open renal biopsies at zero, one, three, six, and 12 months. A distinctive histological lesion, consisting of cytoplasmic vacuolation and accumulation of glycogen in cells lining distal convoluted tubules and collecting ducts, was present in Li (one, three, six, and 12 months), but was absent in Li prior to lithium (zero months) and in C (zero, one, three, six, and 12 months). Histological changes of chronic focal interstitial nephropathy namely, interstitial fibrosis, (quantitated by point counting), tubular atrophy and cast formation (quantitated by digitization), and glomerular sclerosis (determined as the percent of sclerosed glomeruli) showed significant differences between Li and C from as early as one month (interstitial fibrosis, P less than 0.02; tubular atrophy, P less than 0.05; casts, P less than 0.05), and up to 12 months (glomerular sclerosis, P less than 0.05). Distal tubular dilatation and microcyst formation, (quantitated by digitization) was also marked in Li compared with C from one month (P less than 0.05). The degree of distal tubular dilatation and other changes of interstitial nephropathy tended to progress with duration of lithium exposure. Macroscopically, Li kidneys (12 months) were pale, granular, and exhibited microcysts. Raised blood urea (P less than 0.02) and serum creatinine levels (P less than 0.05) were also late features (12 months) of lithium-induced nephropathy. The data support the view that lithium induces chronic renal lesions. The precise relationship between the distinctive distal tubular lesion, distal tubular dilatation and focal interstitial nephropathy remains speculative.     

Sustained ventricular tachycardia and its successful prophylaxis during high-dose bolus interleukin-2 therapy for metastatic renal cell carcinoma

In the setting of interleukin-2 (IL-2) administration, tachycardias of ventricular origin are classified as serious, grade IV toxicities, necessitating the discontinuation of therapy. In this report, we describe a patient with renal cell carcinoma who experienced ventricular tachycardia while undergoing treatment with high-dose bolus IL-2. Prophylaxis with sotalol permitted the successful completion of his first cycle of treatment, without any recurrent rhythm disturbances.     

A variety of appearances of malignant melanoma in the head: a review.

Imaging is frequently requested to evaluate patients with malignant melanoma for metastases. When melanoma metastasizes to the head, the lesions can have a variety of appearances and can occur in a variety of locations. The usual appearances of malignant melanoma on magnetic resonance images include the melanotic and amelanotic patterns. The melanotic pattern consists of high signal intensity on T1-weighted images and low signal intensity on T2-weighted images. In the amelanotic pattern, the lesion is hypointense or isointense to the cortex on T1-weighted images and hyperintense or isointense to the cortex on T2-weighted images. However, there is frequent deviation from these patterns. Other patterns include small and rapidly growing metastases, miliary metastases, and subependymal metastases. Although the brain is the most common site of metastases to the head from melanoma, melanoma can metastasize to almost any intracranial or extracranial structure. Structures in the head that can be involved by metastases from melanoma include bone, muscle, the nasopharynx and mucosa, the parotid gland, the meninges, the choroid plexus, the internal auditory canal, and the orbit. The radiologist needs to be aware of these varied appearances and the relatively ubiquitous sites of involvement to better detect these lesions.     

Incidence and characterization of unifocal mandible fractures on CT

BACKGROUND AND PURPOSE: Conventional thinking among radiologists is that the mandible acts as a closed “ring” that needs to fracture at 2 points, though the frequency of multiple mandible fractures has been reported to be only as high as 67%. However, many of these studies did not use CT to confirm the presence of suggested fractures and excluded nondisplaced fractures. The purpose of this study was to determine the incidence of unifocal mandibular fractures on the basis of detection with dedicated facial bone CT scans and to characterize these fractures.MATERIALS AND METHODS: We retrospectively reviewed the imaging reports of patients during a 3-year period to identify those who had mandible fractures documented on dedicated facial bone CT scans. The incidence of unifocal fractures was determined, the unifocal fractures were further subcategorized, and any derangements of the temporomandibular joints were also evaluated.RESULTS: One hundred two patients met the inclusion criteria. The incidence of unifocal mandible fractures was 42% (43/102). Three unifocal fracture patterns identified were the following: simple fractures (25/42, 58%), comminuted fractures (11/42, 26%), and fractures associated with condylar subluxations (7/42, 16%). Most fractures had none to mild displacement or distraction.CONCLUSION: Unifocal mandible fractures occur with greater frequency than anticipated by most radiologists. This may be due to the somewhat dynamic nature of the mandibular “ring,” which includes the temporomandibular joints, though joint derangements evident on CT occur in the minority of cases.

Fractures of the mandible are a common cause of morbidity from trauma. The mandible is the second most frequently fractured bone in the facial skeleton, and in the setting of motor vehicle crashes, mandible fractures are the most frequent.^1,2 Fractures of the mandible at multiple sites are common and should always be sought radiographically.¹ Conventional thinking among radiologists holds that the mandible, when considered along with the central skull base, is a closed ring that needs to fracture at 2 points. In patients being evaluated for facial fracture in emergency department settings, however, multiple sites of fracture have been reported in up to only 67.9% of patients.¹ A slightly higher percentage (69.8%) has been reported with a selection bias of only patients admitted to the hospital.^1,3 In other series, the incidence of multifocal mandible fractures has been as low as 40%.⁴ Unfortunately, many of these studies did not use CT to confirm the presence of suggested fractures and excluded additional nondisplaced fractures. Helical CT has been reported to be more accurate, sensitive, and specific for the diagnosis of mandibular fractures (particularly in the posterior portions of the mandible) and to have better interobserver agreement and fracture characterization than panoramic tomography.^2,5 Thus, the true incidence of multifocality might be higher than that reported in the literature, which is based on studies in which all patients did not receive dedicated facial bone CT scans. The purpose of this study was to determine the incidence of unifocal mandible fractures on the basis of detection with dedicated facial bone CT scans and to characterize these fractures.     

Effect of a calcitonin gene-related peptide antagonist (CGRP8-37) on skin vasodilatation and oedema induced by stimulation of the rat saphenous nerve.

1. The effect of the calcitonin gene-related peptide antagonist (CGRP8-37, 400 nmol kg-1, i.v.) on the increased blood flow induced by calcitonin gene related peptide (CGRP), vasodilator prostaglandins, and topical capsaicin was measured with a laser Doppler blood flow meter in rat abdominal skin. 2. The saphenous nerve was electrically stimulated and the effect of CGRP8-37 (400 nmol kg-1, i.v.) on the increased blood flow (measured by laser Doppler flowmetry) and oedema formation (measured by the extravascular accumulation of [125I]-albumin) was investigated in the rat hind paw. 3. CGRP8-37 (400 nmol kg-1, i.v.) had no effect on basal cutaneous blood flow at uninjected sites and sites injected with Tyrode buffer, but acted selectively to inhibit the increased blood flow induced by intradermal CGRP (10 pmol/site, P < 0.05), but not that induced by prostaglandin E2 (PGE2, 300 pmol/site) or carba-prostacyclin (cPGI2, 100 pmol/site). 4. Capsaicin (0.1-33 mM), applied topically, acted in a dose-related manner to increase blood flow. CGRP8-37 (400 nmol kg-1, i.v.) almost totally inhibited blood flow induced by capsaicin (10 mM; P < 0.05) but did not significantly inhibit blood flow induced by a higher dose of capsaicin (33 mM). 5. The increased blood flow induced by short stimulation of the saphenous nerve (10 V, 1 ms, 2 Hz for 30 s) was inhibited by 76%, 5 min after i.v. CGRP8-37 (400 nmol kg-1, i.v., P < 0.05). 6. A longer (5 min) electrical stimulation of the saphenous nerve caused oedema formation, in addition to increased blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Preliminary evaluation of a coping strategy enhancement method of preparation for labour

OBJECTIVES: To compare the use and effects of enhanced pre-existing coping strategies with the use and effects of coping strategies usually taught in National Health Service (NHS) antenatal education on women's experience of pain and emotions during labour. DESIGN: A between-group comparison of women who chose to attend NHS antenatal education where courses of preparation were randomly assigned to include either a new method of coping strategy enhancement (CSE) or standard taught coping strategies. SETTING: Two large maternity units in one city in the North of England. PARTICIPANTS: 20 women participated in antenatal classes incorporating the CSE method and 21 women participated in antenatal classes incorporating the standard approach to developing coping strategies for labour. FINDINGS: Women who attended CSE classes used enhanced coping strategies for a larger proportion of their labour than women who attended standard classes who used taught coping strategies. Birth companions were more involved in women's use of enhanced than taught strategies. Self-efficacy for use of coping strategies and subsequent experiences of pain and emotions during labour were equivalent between groups. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: An approach based on enhancing pre-existing coping strategies was associated with greater coping strategy use and involvement from the birth companion, and provided benefits to women's overall experience of labour at least equivalent to that associated with standard preparation. Further research should explore this novel approach in larger groups, and for women who may choose not to attend group antenatal preparation.