[Significance of sentinel lymph node biopsy in Merkel cell carcinoma. Analysis of 11 cases]

BACKGROUND

Merkel cell carcinoma is an aggressive cutaneous neoplasm with a high propensity for nodal metastases. Regional lymph node involvement develops in 45 to 65 p. 100 of patients. We evaluated in Merkel cell carcinoma the use of sentinel lymph node biopsy which allows the identification of occult nodal metastases.

PATIENTS AND METHODS

Eleven patients diagnosed with Merkel cell carcinoma without clinical nodal involvement underwent pre-operative lymphoscintigraphy followed by sentinel lymphadenectomy with histologic analysis. Identification of microscopic nodal metastases led to complete lymph node dissection and adjuvant radiation therapy to the lymph node basin.

RESULTS

The sentinel lymph node was successfully identified in 9 patients. Two patients demonstrated metastatic disease in their sentinel lymph nodes. At subsequent complete node dissection, one of two patients had an additional metastatic lymph node. None of the eleven patients experienced recurrent disease at a follow-up varying from 1 to 42 months. One patient with a negative sentinel lymph node experienced lymphoedema.

COMMENTS

Our results are consistent with the 14 published studies which totalled 93 patients with Merkel cell carcinoma and identified 29 patients (30 p. 100) with nodal involvement. Metastatic disease was identified only after immunohistochemical analysis in 20 p. 100 of these patients (n=6). Lymph node involvement appears to be a bad prognostic factor with 29.6 p. 100 of disease recurrence, as opposed to 3 p. 100 in patients with an uninvolved sentinel lymph node. Although the prognostic significance of this technique seems interesting, there is no optimal therapeutic approach to sentinel lymph node involvement.

Surgical management of the cutaneous manifestations of linear nevus sebaceus syndrome

Linear nevus sebaceus syndrome is characterized by the association of nevus sebaceus covering extensive areas on the head and scalp with abnormalities of the central nervous system, ophthalmologic and skeletal changes, and malignancies. The incidence is approximately one per 10,000 live births, and there is no sexual predilection reported. The original description of this syndrome was followed by extensive literature describing the dermatologic, neurologic, and ophthalmologic manifestations of this disease. The objective of this report is to describe the surgical approach for the excision and reconstruction of giant sebaceous nevi of the face and scalp in children with linear nevus sebaceus syndrome on the basis of a consecutive series of five patients treated over 10 years in the same institution. To the authors' knowledge, this report represents the largest surgical series and suggests a reliable approach to the treatment of the cutaneous manifestations of this syndrome.

Ear reconstruction after auricular chondritis secondary to ear piercing

The recent fad of high ear piercing in the pinna has led to an increased incidence of auricular chondritis, which leads to dissolution of the cartilage and residual ear deformity. The typical postpiercing chondritis deformity presents as a structural collapse of the superior helical rim, scaphal cartilage, and the adjacent antihelix. The skin envelope is usually preserved, but it may be scarred from the infectious process and from previous drainage incisions. In the present article, the authors present a systematic approach to reconstruction of these acquired ear deformities. Careful assessment of the residual tissue is requisite to planning and appropriate reconstruction. The greater the cartilage loss, the more structural support is required to expand the skin envelope to its normal size and shape. The choice of cartilage donor site is made on the basis of the size of the defect and may include ipsilateral or contralateral conchal cartilage, bilateral conchal cartilage, or costal cartilage. Redraping of the carefully dissected skin and fixation of the flaps to the newly reconstructed cartilaginous framework usually provide sufficient soft-tissue coverage. A temporal-parietal fascial flap is preserved for the rare cases of extensive full-thickness skin loss or badly damaged and scarred auricular skin.

Presence of phosducin in the nuclei of bovine retinal cells

PURPOSE

During the course of our investigations on cyclic nucleotide dependent-phosphorylation of membrane proteins, we observed that phosducin was present in both the cytosolic and nuclear fractions. It has been suggested that phosducin might have a role in regulating transcription, but its presence in the nucleus has not been previously reported. We therefore attempted to purify nuclei from bovine retina and determine whether the purified preparation contained phosducin. Cyclic nucleotide-dependent phosphorylation of the protein was also investigated in the homogenate and subcellular fractions of bovine retina.

METHODS

Freshly obtained bovine retinas were homogenized and fractionated in an isotonic buffer. The homogenate and subcellular fractions were subjected to phosphorylation in the presence of gamma-32P ATP and the presence and absence of cyclic GMP. The phosphorylated proteins were identified by 1- or 2-dimensional electrophoresis and autoradiography. Phosducin was detected in the fractions by western blotting. A nuclear preparation was obtained from the homogenate by sucrose gradient centrifugation, its purity was determined with a nuclear stain, and the presence and phosphorylation of phosducin was investigated as above.

RESULTS

Phosducin was found in the cytosol, 100,000x g membrane fraction, as well as in the 120x g pellet of a fresh, isotonic retinal homogenate, but cyclic nucleotide-dependent phosphorylation of the protein was observed only in the cytosolic fraction. Western blotting on a highly purified nuclear fraction showed that phosducin was present in the nuclei. The protein could be phosphorylated in a cyclic GMP-dependent fashion in a nuclear preparation permeabilized by freezing and thawing.

CONCLUSIONS

It has been suggested that a C-terminal fragment of phosducin might be transported into the nucleus where it might have a role in the regulation of transcription. Phosducin localization in the nucleus was shown in COS cells cotransfected with genes of phosducin and a transcription factor. However, the presence of phosducin in the nuclei of retina has not been demonstrated hitherto. The present results show that phosducin is present in the nuclei in bovine retina. It could be phosphorylated in the nuclei in a cyclic GMP-dependent fashion. These results support a possible role for phosducin in the regulation of transcription.

Effects of lithium on basal and modulated activities of the particulate and soluble guanylate cyclases in retinal rod outer segments

A large amount of information regarding the kinetics of biochemical reactions involved in visual transduction was derived from electrophysiological studies on dark-adapted rod outer segments. Hodgkin et al. [(1985) J. Physiol. 358, 447-468] observed that when Na was replaced with Li in the perfusion solution bathing the rod outer segment, the dark current slowly declined to zero. This decline was thought to result from a rise in intracellular calcium which was hypothesized to inhibit guanylate cyclase activity and reduce the cyclic GMP concentration. Rod outer segments contain membrane and soluble guanylate cyclase activities, and we show here that Li directly inhibits both types of activities very strongly. Both the basal (at high calcium) and the stimulated (at low calcium) activities of the membrane enzyme were inhibited by Li. Half-maximal inhibition of the stimulated enzyme was at 30 mM Li while for the basal activity it was at 100 mM. Over 80% of the activated enzyme was inhibited at 110 mM Li. The soluble guanylate cyclase activity was stimulated by nitroprusside. One hundred millimolar Li inhibited the basal activity by 20-30%, but the inhibition of the nitroprusside-stimulated (soluble) enzyme was much stronger, resembling that of the activated membrane enzyme. Half-maximal inhibition occurred at 30 mM, and about 80% inhibition was found at 100 mM Li. Stimulation of the soluble enzyme by nitroprusside was independent of calcium in the physiological range. The inhibition of the stimulated enzyme by Li was similarly independent of calcium, except at unphysiologically high concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Diffraction-enhanced X-ray imaging of articular cartilage

OBJECTIVE

To introduce a novel X-ray technology, diffraction-enhanced X-ray imaging (DEI), in its early stages of development, for the imaging of articular cartilage.

DESIGN

Disarticulated and/or intact human knee and talocrural joints displaying both undegenerated and degenerated articular cartilage were imaged with DEI. A series of three silicon crystals were used to produce a highly collimated monochromatic X-ray beam to achieve scatter-rejection at the microradian level. The third crystal (analyser) was set at different angles resulting in images displaying different characteristics. Once the diffraction enhanced (DE) images were obtained, they were compared to gross and histological examination.

RESULTS

Articular cartilage in both disarticulated and intact joints could be visualized through DEI. For each specimen, DE images were reflective of their gross and histological appearance. For each different angle of the analyser crystal, there was a slight difference in appearance in the specimen image, with certain characteristics changing in their contrast intensity as the analyser angle changed.

CONCLUSIONS

DEI is capable of imaging articular cartilage in disarticulated, as well as in intact joints. Gross cartilage defects, even at early stages of development, can be visualized due to a combination of high spatial resolution and detection of X-ray refraction, extinction and absorption patterns. Furthermore, DE images displaying contrast heterogeneities indicative of cartilage degeneration correspond to the degeneration detected by gross and histological examination.

[Delayed cerebral radionecrosis following radiation therapy of cutaneous squamous cell carcinomas of the head]

INTRODUCTION

Three cases of cerebral radionecrosis occurring after radiation therapy for squamous cell carcinomas of the scalp are reported. This rare and poorly documented complication of radiotherapy is discussed.

CASE REPORTS

Three patients presenting with squamous cell carcinomas of the scalp were treated with surgery and radiotherapy for recurrent or incomplete resection of squamous cell carcinomas of the head. X-ray doses range were 50 to 60 Grays in 22 to 24 fractions. Cerebral radionecrotic lesions were diagnosed 6 months to 14 years after irradiation, and were inconstantly associated with clinical symptoms. The patients were treated with systemic steroids, which were of limited efficacy in one of our patients.

DISCUSSION

Little is known of cerebral radionecrosis following radiotherapy. This may be related to their rare occurrence and/or to the difficulties in establishing diagnosis. The delay of occurrence after radiotherapy can vary between a few months and several years, and the lesions are directly correlated with the doses and the fractionning of the X-rays. Intracerebral localization of the tumour is the main differential diagnosis. Localized and cystic forms of cerebral radionecrosis can be treated by surgery. Treatment otherwise relies on systemic steroids.

Indium-111 octreotide scintigraphy of Merkel cell carcinomas and their metastases

BACKGROUND

Somatostatin receptor scintigraphy (SRS) may be of interest for staging Merkel Cell Carcinoma (MCC). This study was undertaken to evaluate the sensitivity and specificity of SRS and to determine its role compared to conventional investigations.

PATIENTS AND METHODS

From 1993 to December 2000, 20 patients (10 females and 10 males, aged from 38 to 88, mean 66 years) were included prospectively. At the time of SRS: 12 patients had been diagnosed as having stage I disease, 6 stage II and 4 stage III. Two patients had two SRS studies during the course of their disease. SRS was performed with Indium-111 pentetreotide (Octreoscan), a radiolabelled somatostatin analogue. Patients were treated according to the clinical stage. A regular follow-up was scheduled every three months.

RESULTS

SRS depicted stage I and II MCC tumour sites with an overall sensitivity of 78% (95% confidence interval (CI): 40%-97%) and a specificity of 96% (81%-100%). The histopathological diagnosis was used as the gold standard. Sites visualised by SRS were compared to those detected with conventional modalities and to follow-up data for all stages: SRS visualised four out of five primary tumour sites, six out of eight lymph node sites, no skin metastases (14 sites in 2 patients), two out of three thoracic metastases and zero out of two hepatic metastases. SRS did not influence treatment decision-making in any of the cases.

CONCLUSIONS

Although SRS seems highly specific in MCC and could be of help in difficult cases, it cannot be recommended for routine evaluation.

Evaluation of cosmetic results of a randomized trial comparing surgery and radiotherapy in the treatment of basal cell carcinoma of the face

Basal cell carcinoma is the most frequent cutaneous carcinoma, and it is characterized by its local spreading and an exceptional tendency to metastasize. Radical excision or destruction ensures the highest chance of cure. The most frequent site of this tumor is the face, where radical excision is limited by the proximity of essential anatomic structures. The main difficulty is to avoid mutilation and to provide good cosmetic results despite the vicinity of the eyes, the nose, and the mouth. Surgery and radiotherapy are known to provide similar chances of cure, but results concerning cosmetic sequelae are controversial, depending sometimes on the specialty of the physician in charge of the treatment. A randomized trial was performed at the Gustave-Roussy Institute to compare basal cell carcinomas of the face treated either by surgery or by radiotherapy. In summary, a significant advantage was observed in favor of surgery, as has been published elsewhere. Looking at the details of the cosmetic results, we analyzed the specific methodology of the cosmetic evaluation set up to eradicate the usual bias owing to subjective judgments. We looked also to the evolution of the cosmetic results with time. A panel of five judges performed repeated evaluations during the follow-up, and standardized photographs were taken at each visit and rated later by three nonmedical judges. In total, 174 patients were treated by surgery and 173 by radiotherapy; the choice of the treatment was allocated by randomization. Postoperative complications were higher in the radiotherapy group. The final cosmetic results after 4 years of follow-up were rated significantly better with surgery than with radiotherapy (good in 87 percent versus 69 percent according to the patient, 79 percent versus 40 percent according to the dermatologist, and respectively for each of the observers). Evolution of the ratings during the follow-up demonstrated an improvement of the cosmesis after surgery and stable or deteriorated results after radiotherapy. The same trend was observed regardless of the site of the tumor on the face, except for the nose, where the difference--still in favor of the surgery--was not significant. Concordance of all assessments in our study was the main guarantee of reliability of our methodology for cosmetic evaluation.

Rate of deactivation of nitric oxide-stimulated soluble guanylate cyclase: influence of nitric oxide scavengers and calcium

Soluble guanylate cyclase (sGC) is highly activated by nitric oxide (NO) and is the known mediator of the effects of NO on a variety of physiological processes. The rates at which sGC is activated and deactivated are therefore of wide interest since they determine the duration of a tissue's response to NO. The effect of NO on smooth muscle dissipates in 1-2 min, suggesting that both activation and deactivation are fast. In vitro measurements show that the activation of sGC occurs in less than a second, while the deactivation takes several hours at 20 degrees C. However, recent reports indicate that Mg-GTP, oxyhemoglobin, and reducing and oxidizing agents could deactivate the cyclase in several seconds to minutes, though the effectiveness of each of these agents is in dispute. We investigated the lifetime of NO-sGC in the cytosol of retina by monitoring its enzymatic activity at 20 degrees C. Our results show that Mg-GTP, the substrate of NO-sGC, has no influence on the deactivation. Similarly, reducing agents glutathione and dithiothreitol shortened the half-life of NO-sGC only by about 30%. The greatest effect on the deactivation was caused by scavengers of NO: oxyhemoglobin reduced the half-life of NO-sGC from 106 min to 18 s; another NO scavenger, 2-(4-carboxyphenyl)-4,4,5, 5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO), reduced it to 42 s (20 degrees C). Similarly rapid deactivation was observed with the enzyme from bovine lung, immunoprecipitated enzyme from bovine retina, and heme-deficient enzyme from bovine retina reconstituted with heme. On the other hand, YC-1, an activator of sGC, stabilized the activated enzyme, preventing NO dissociation, as was evident from the inability of oxyhemoglobin or CPTIO to deactivate NO-sGC. Calcium, which is known to inhibit NO-sGC, also inhibited the effects of oxyhemoglobin and CPTIO, slowing down the deactivation of the enzyme. Lithium, which is also known to inhibit NO-sGC, had no effect on the deactivation rate of the enzyme. These results, taken together, suggest that two factors with major impact on the lifetime of NO-sGC are the proximity to NO scavengers and the calcium concentration in the cell.

[Cerebral magnetic resonance imaging (MRI) in the diagnosis of leptomeningeal carcinomatosis in melanoma patients]

OBJECTIVE

Meningeal involvement is frequent in metastatic melanoma, approximately 30% in autopsy series. Functional signs may be misleading and the neurological examination may be normal. Certain diagnosis requires identification of tumor cells in the cerebrospinal fluid. CSF cytology is however sometimes negative and magnetic resonance imaging (MRI) with gadolinium injection may provide the diagnosis. The aim of this retrospective study was to assess the role of imaging in the diagnosis of leptomeningeal carcinomatosis.

PATIENTS AND METHODS

The diagnosis of leptomeningeal carcinomatosis was made in 8 patients between 1992 and 1998. All had signs of neurological function impairment, but the neurology examination was abnormal in only 2.

RESULTS

Cytology examination of the cerebrospinal fluid provided the diagnosis of leptomeningeal carcinomatosis in 5 patients. One out of 5 brain CT scans were positive, showing meningeal enhancement confirmed by brain MRI. The spinal tap was not contributive in 2 cases and was not done in 1. In these three cases, the brain CT did not provide any diagnostic element while the brain MRI with gadolinium injection confirmed the diagnosis of leptomeningeal carcinomatosis.

DISCUSSION

Forty-one percent of patients with autopsy proven leptomeningeal carcinomatosis have a normal ante mortem spinal tap. Brain MRI with gadolinium injection has better sensitivity than brain CT scan. All patients with nonspecific neurological signs and a normal spinal tap should be explored with a brain MRI.

Antisense inhibition of hyaluronan synthase-2 in human articular chondrocytes inhibits proteoglycan retention and matrix assembly

In order to define the role of cell-associated hyaluronan in cartilage matrix retention, human articular chondrocytes as well as cartilage slices were treated with phosphorothioate oligonucleotides comprised of sequence antisense to the mRNA of human HA synthase-2 (HAS-2). As a prerequisite for these studies, it was necessary to determine which HA synthase (HAS), of three separate human genes capable of synthesizing HA, designated HAS-1, HAS-2, or HAS-3, is primarily responsible for HA synthesis in human articular chondrocytes. The copy number of each HAS mRNA expressed in cultured human articular chondrocytes was determined using quantitative (competitive) reverse transcription-polymerase chain reaction (RT-PCR). Only HAS-2 and HAS-3 mRNA expression was detected. The level of HAS-2 mRNA expression was 40-fold higher than that of HAS-3. Cultures of human articular chondrocytes and cartilage tissue slices were then transfected with HAS-2-specific antisense oligonucleotides. This treatment resulted in time-dependent inhibition of HAS-2 mRNA expression, as measured by quantitative RT-PCR, and a significant loss of cell-associated HA staining. Sense and reverse HAS-2 oligonucleotides showed no effect. The consequences of reduced HA levels (due to HAS-2 antisense inhibition) were a decrease in the diameter of the cell-associated matrix and a decreased capacity to retain newly synthesized proteoglycan. These results suggest that HA synthesized by HAS-2 plays a crucial role in matrix assembly and retention by human articular chondrocytes.

[Plagiocephaly in children: etiology, differential diagnosis and helmet treatment]

Plagiocephaly in a head-and-neck irradiated rat model or rhomboid-shaped head, occurs in at least 1 in 300 live births. In most cases such asymmetry is not caused by synostosis of the unilateral coronal or lambdoid sutures, but is rather a deformity produced by intrauterine and/or postnatal deformational forces. Categorization and diagnosis of plagiocephaly as synostotic or deformational is reliably made by physical examination and computerized tomography. Its differential diagnosis is extremely important because prompt surgical correction is usually indicated for the synostotic type. In contrast, infants with deformational frontal or occipital plagiocephaly generally respond to helmet treatment. 10 infants with significant deformational plagiocephaly were treated with individual plastic helmets during the past 2 years and 4 other infants with plagiocephaly are currently being treated. In each instance, cranial asymmetry dramatically improved as the brain grew and the head filled out the helmet. There were no significant complications. Awareness of deformational plagiocephaly allows more accurate diagnosis and appropriate treatment, avoiding unnecessary surgical intervention in patients with positional molding.

[Primary cutaneous leiomyosarcoma: 32 cases]

BACKGROUND

Superficial leiomyosarcomas are rare tumors, which may be confined to the dermis or extend to subcutaneous tissues.

PATIENTS AND METHODS

We report the results of a retrospective study of 32 patients treated for leiomyosarcomas through a twenty-two year period (from 1975 to 1997).

RESULTS

Mean age was 45 years, with 50 p. 100 of patients less than 35 years of age. Forty seven percent of the tumors were located on the lower limbs and mean diameter was 2.8 cm. Three clinical types have been isolated: nodule beneath normal epidermis (50 p. 100), purple nodule ulcerated or not (28 p. 100), swelling tumor (22 p. 100). Sixteen percent were intradermal, whereas sixty nine percent involved subcutaneous tissues. With regard to tumor grade, 37 p. 100 of tumors were grade I, 44 p. 100 of tumors were grade II, and 19 p. 100 were grade III. Immunohistochemical staining showed positive reactions for all tumors with anti-vimentin and anti-alpha smooth muscle actin. Main treatment was complete surgical excision. Follow-up informations were available for all patients and 75 p. 100 of them had a follow up period longer than a year. Five patients with leiomyosarcomas involving the subcutis developed local recurrences, and two of them died of the disease.

DISCUSSION

Leiomyosarcomas can occur at any age without predominant sex-ratio. Main prognostic factors are tumor size, distal location, depth of tumor invasion and pathological grade. Immunohistological staining with anti-alpha smooth muscle actin is more sensitive and specific than with anti-desmin or anti-HHF 35. Main treatment is surgical excision with wide margins.

Prognostic value of high-frequency sonography and color Doppler sonography for the preoperative assessment of melanomas

OBJECTIVE

The purposes of this study were to determine the efficacy of high-frequency sonography for the preoperative assessment of melanomas and to determine the prognostic value of tumor vascularity measured by color Doppler sonography.

SUBJECTS AND METHODS

Twenty-seven patients with melanomas were prospectively examined using high-frequency sonography before they underwent surgery. For each tumor, morphologic evaluation (20-MHz probe), including the measurement of maximum tumor thickness, and color Doppler sonography analysis (13-MHz probe), including the measurement of intratumor vascularity, were performed. Diagnosis was confirmed by histologic findings, tumor thickness was measured using the Breslow index, and vascularity was assessed by immunochemical findings.

RESULTS

Each of the 27 melanomas was depicted on high-frequency sonography as a homogeneous hypoechoic structure with well-defined margins. Tumor thickness was measured using high-frequency sonography as ranging from 0.3 to 8.0 mm, whereas it was measured using the Breslow index as ranging from 0.26 to 8.0 mm. Sonography measurements and Breslow index values were strongly correlated (r > .95). In the cases in which the Breslow index value exceeded 1 mm (n = 11), surgical reexcision was necessary but could have been avoided if surgery had been planned on the basis of high-frequency sonography measurements. Intratumor vessels were depicted on color Doppler sonography (n = 10). Color Doppler sonography data and histologic findings were significantly correlated.

CONCLUSION

High-frequency sonography is a simple, reliable, noninvasive, and accurate method for the preoperative measurement of melanoma thickness. In fact, surgical planning could be adapted according to this measurement. The prognostic value of vascularization evaluated with color Doppler sonography is comparable with that determined by the Breslow index.

Soluble guanylate cyclase and nitric oxide synthase in synaptosomal fractions of bovine retina

Cyclic GMP has been shown in recent years to directly activate ion channels in bipolar and ganglion cells, and to indirectly regulate coupling between horizontal cells, and between bipolar and amacrine cells. In all of these cases, the effects of cyclic GMP are mimicked by nitric oxide. An increase in calcium concentration stimulates the production of nitric oxide by neuronal and endothelial forms of nitric oxide synthase, which in turn activates soluble guanylate cyclases, enhancing the synthesis of cyclic GMP. Though some effects of nitric oxide do not involve cyclic GMP, the nitric oxide-cyclic GMP cascade is well recognized as a signaling mechanism in brain and other tissues. The widespread occurrence of nitric oxide/cyclic GMP-regulated ion channel activity in retinal neurons raises the possibility that nitric-oxide-sensitive soluble guanylate cyclases play an important role in cell-cell communication, and possibly, synaptic transmission. Immunohistochemical studies have indicated the presence of soluble guanylate cyclase in retinal synaptic layers, but such studies are not suitable for determination of the density or quantitative subcellular distribution of the enzyme. Microanalytical methods involving microdissection of frozen retina also showed the presence of cyclase activity in retinal plexiform layers but these methods did not permit distinction between nitric oxide-sensitive and insensitive cyclases. In this study, we fractionated retinal homogenate into the cytosolic and synaptosomal fractions and investigated the specific activity and distribution of soluble guanylate cyclase and nitric oxide synthase. The results show that both enzymes are present in the synaptosomal fractions derived from inner and outer plexiform layers. The synaptosomal fraction derived from inner retina was highly enriched in cyclase activity. Nitric oxide synthase activity was also higher in the inner than outer retinal synaptosomal fraction. The results suggest that the nitric oxide-cyclic GMP system is operational in both synaptic layers of retina and that it may play a more significant role in the inner retina.

Identification of effector binding sites on S100 beta: studies with guanylate cyclase and p80, a retinal phosphoprotein

S100 beta is a calcium-binding protein, which regulates the activities of several enzymes and inhibits the phosphorylation of a variety of protein kinase C substrates in a calcium-dependent manner. The protein was recently found to activate a retinal membrane guanylate cyclase, and in this paper, we report that it inhibits the phosphorylation of an 80 kDa retinal protein (p80). Structurally, S100 beta consists of two EF-hands connected by a hinge region. In view of its small size, wide distribution in a variety of tissues, and regulation of many different proteins, it is of interest to identify the sites on the protein that interact with the effectors, and to determine if the same sites are responsible for interaction with different effectors. We addressed these questions with the use of synthetic peptides with sequences corresponding to different regions of S100 beta and testing their effects on the protein's activation of guanylate cyclase, and inhibition of p80 phosphorylation. Peptides with sequences corresponding to effector interaction sites were anticipated to either block or simulate the effects of S100 beta. The results show that two regions of S100 beta interact with effectors: the C-terminal region of Thr81-Glu91 and the hinge region of Leu32-Leu40. The synthetic peptide containing the latter sequence blocked the S100 beta activation of guanylate cyclase and inhibition of p80 phosphorylation, while the peptide containing the former sequence blocked cyclase activation and simulated S100 beta in inhibiting p80 phosphorylation. By determining the effects of including or excluding dithiothreitol in the assays, we observed that the cysteine residue in the C-terminal region of S100 beta (Cys84) participates in the regulation of guanylate cyclase but not of p80 phosphorylation. We conclude from these results that the C-terminal and hinge regions of S100 beta are important in the regulation of effector proteins and that Cys84 is essential for interaction with only specific effectors.

[Microcystic sclerosing adnexal carcinoma: 2 case reports. Diagnostic and therapeutic difficulties]

Microcystic adnexal carcinoma is a recently described malignant neoplasm of adnexal structure. It remains frequently misdiagnosed. These tumors are characterized by their slow progression and by local aggressivity with local recurrences. The best treatment appears to be surgical excision with microscopically controlled margin. We report two cases of microcystic adnexal carcinoma recently observed at Institute Gustave Roussy.

Structural and functional characterization of retinal calcium-dependent guanylate cyclase activator protein (CD-GCAP): identity with S100beta protein

Calcium-dependent guanylate cyclase activator protein (CD-GCAP) is a low-molecular-weight retinal calcium-binding protein which activates rod outer segment guanylate cyclase (ROS-GC) in a calcium-dependent manner. This investigation was undertaken to determine the protein's structure and identity. Partial amino acid sequencing (72% of the protein), mass spectral analysis, cloning, and immunological studies revealed that CD-GCAP is identical to S100beta, another low-molecular-weight calcium-binding protein whose structure was known. We had shown earlier that the latter protein, which is usually called S100b (S100betabeta or dimer of S100beta), also activates ROS-GC but that the Vmax of activated cyclase was about 50% lower than when stimulated by CD-GCAP. S100b also required about 15 times more calcium (3.2 x 10(-)5 vs 1.5 x 10(-)6 M) for half-maximal stimulation of cyclase. To investigate the possibility that CD-GCAP is a post-translationally modified form of S100b, both proteins were treated with 1 M hydroxylamine which is known to deacylate proteins. After the treatment, CD-GCAP did not activate cyclase while S100b activation remained unaffected suggesting that CD-GCAP could not be a modified form of S100b. Hydroxylamine also broke down CD-GCAP into smaller fragments while leaving S100b intact. It therefore appeared that in spite of identical primary structures, the conformations of the two proteins were different. We then investigated the possibility that the purification procedures of the two proteins, which were quite different, could have contributed to such conformational differences: CD-GCAP purification included a step of heating at 75 degrees C in 5 mM Ca, while S100b purification included zinc affinity chromatography. To test the influence of these treatments on the properties of the proteins, CD-GCAP was subjected to zinc affinity chromatography and purified as S100b (CD-GCAP-->S100b) and S100b was heated in Ca and purified as CD-GCAP (S100b-->CD-GCAP). Cyclase activation, calcium-sensitivity, and hydroxylamine-lability measurements revealed that CD-GCAP-->S100b is identical to S100b and that S100b-->CD-GCAP is identical to CD-GCAP. Taken together the results demonstrate that CD-GCAP and S100b are one and the same protein and that their functional differences are due to different interconvertible conformational states.

Value of high-frequency US for preoperative assessment of skin tumors

The purpose of this study was to evaluate the accuracy of high-frequency ultrasound (US) in the preoperative assessment of skin tumors. A US scanner with a 20-MHz probe was used to visualize and evaluate 70 skin lesions (38 clinically suspected melanomas and 32 suspected basilar cell carcinomas [BCCs]) before surgical resection. A US morphologic study and a Doppler analysis of vascularity were performed for each tumor. Of the 70 tumors, 62 were clearly visualized, including 19 melanomas, 12 nonmalignant nevi, and 31 BCCs. Most lesions were hypoechoic. In 13 of 19 proved melanomas, the difference between the histologic and US measurements was equal to or less than 0.2 mm. Vessels were visualized in melanomas with thicknesses greater than 3 mm. All BCCs were visualized, and in 29% of cases of BCC, tumor size at US was greater than that at clinical examination. High-frequency, high-resolution US is a simple, reliable, noninvasive method for accurate preoperative assessment of skin tumor dimensions. This technique allows surgical planning to be adapted and reexcision to be avoided. However, its role is limited in the differential diagnosis of malignant and benign skin lesions.

Intratumoral oxygen tension in metastatic melanoma

Tumour hypoxia can lead to a decrease in the biological effectiveness of radiation and alkylating agents. Few data are available on oxygen tension (PO2) in melanoma. In 20 patients with past history of melanoma, PO2 was evaluated in normal tissues and suspected metastatic lesions (nodes and skin metastases). Oxygen tension was measured using a needle probe technique (KIMOC-6650 histograph, Eppendorf, Germany), the day before the surgical removal of the suspected metastatic lesion. Histological confirmation of the malignant origin of the removed lesion was obtained in 18 cases. In two cases invasion by the known melanoma was not seen histologically. The median PO2 for normal tissues was 40.5 mmHg. For tumours, the median PO2 was 11.6 mmHg, and it was 17.1 mmHg in nodes and 6.7 mmHg in skin metastases. Very low values (< 2 mmHg) accounted for 20% of the recorded values in nodes and 15% in skin metastases. When analysed according to the node size (< or > or = 3 cm in diameter), the median PO2 was 10.4 mmHg in large nodes (six patients) and 53.3 mmHg in small nodes (six patients). For the two non-tumoral lesions, the median PO2 values were 20.9 and 25.1 mmHg, with no values below 10 mmHg. Thus a decrease in PO2 values, probably corresponding to tumour hypoxia, was found in most of the metastatic tumours when compared with normal tissues. The prognostic value of these PO2 measurements in melanoma remains to be demonstrated in the tumour response to radiotherapy or alkylating agents. However, tumour hypoxia can already be investigated as a target for new treatment modalities in metastatic melanoma.