[Osteosynthesis of metacarpal fractures with 2.0 mm LCP system and functional postoperative treatment]. / Osteosynthese von Metakarpalefrakturen mit 2,0-mm-LCP und funktionelle postoperative Nachbehandlung.

BACKGROUND: Locking head systems are an additional option in the surgical treatment of metacarpal fractures. In this clinic 2.0 mm locking compression plates (LCP) are used, which provide the possibility of functional postoperative treatment even for complex and osteoporotic metacarpal fractures. For simple fractures and good bone quality the LCP system is used as a compression or neutralization plate. Depending on the type and localization of the fracture, different osteosynthesis techniques are used in order to achieve a functional postoperative treatment in as many patients as possible. MATERIAL AND METHODS: Between July 2009 and December 2010 a total of 49 patients were enrolled in a prospective trial. All patients underwent surgical treatment with a 2.0 mm LCP system. Postoperative functionality of the hand was restored without immobilization. Clinical and radiological examinations were performed after 6 and 12 weeks and after 6 and 12 months with documentation of the range of motion (ROM), grip strength, fingertip to palm distance and the disabilities of the arm, shoulder and hand (DASH) score. RESULTS: After 6 months a good functional result was achieved in all patients with no cases of malrotation. Radiographs showed a completely consolidated bone healing. CONCLUSION: After osteosynthesis with 2.0 mm LCPs all types of metacarpal fractures can be treated without immobilization.

Gender-specific hip fracture risk in community-dwelling and institutionalized seniors age 65 years and older.

UNLABELLED: In this study of acute hip fracture patients, we show that hip fracture rates differ by gender between community-dwelling seniors and seniors residing in nursing homes. While women have a significantly higher rate of hip fracture among the community-dwelling seniors, men have a significantly higher rate among nursing home residents. INTRODUCTION: Differences in gender-specific hip fracture risk between community-dwelling and institutionalized seniors have not been well established, and seasonality of hip fracture risk has been controversial. METHODS: We analyzed detailed data from 1,084 hip fracture patients age 65 years and older admitted to one large hospital center in Zurich, Switzerland. In a sensitivity analysis, we extend to de-personalized data from 1,265 hip fracture patients from the other two large hospital centers in Zurich within the same time frame (total n = 2,349). The denominators were person-times accumulated by the Zurich population in the corresponding age/gender/type of dwelling stratum in each calendar season for the period of the study. RESULTS: In the primary analysis of 1,084 hip fracture patients (mean age 85.1 years; 78% women): Among community-dwelling seniors, the risk of hip fracture was twofold higher among women compared with men (RR = 2.16; 95% CI, 1.74-2.69) independent of age, season, number of comorbidities, and cognitive function; among institutionalized seniors, the risk of hip fracture was 26% lower among women compared with men (RR = 0.77; 95% CI: 0.63-0.95) adjusting for the same confounders. In the sensitivity analysis of 2,349 hip fracture patients (mean age 85.0 years, 76% women), this pattern remained largely unchanged. There is no seasonal swing in hip fracture incidence. CONCLUSION: We confirm for seniors living in the community that women have a higher risk of hip fracture than men. However, among institutionalized seniors, men are at higher risk for hip fracture.

Before and after hip fracture, vitamin D deficiency may not be treated sufficiently.

UNLABELLED: Our findings show that only about 20% of seniors receive vitamin D supplementation prior to their index hip fracture or after the event. We further confirm the high prevalence of severe vitamin D deficiency in this population and show that those who receive supplementation have significantly higher 25-hydroxyvitamin D (25(OH)D) status. INTRODUCTION: The aim of this study is to assess current practice in pre- and post-hip fracture care practice with respect to vitamin D supplementation. METHODS: We surveyed 1,090 acute hip fracture patients age 65 and older admitted to acute care for hip fracture repair; 844 had serum 25-hydroxyvitamin D levels measured upon admission to acute care, and 362 agreed to be followed at 12 month after their hip fracture. Prevalence of vitamin D supplementation was assessed upon admission to acute care (at the time of hip fracture), upon discharge from acute care, and at 6 and 12 months follow-up. RESULTS: Of 1,090 acute hip fracture patients (mean age 85 years, 78% women, 59 % community-dwelling), 19% had received any dose of vitamin D prior to the index hip fracture, 27% (of 854 assessed) at discharge from acute care, 22 % (of 321 assessed) at 6 month, and 21% (of 285 assessed) at 12 month after their hip fracture. At the time of fracture, 45% had 25(OH)D levels below 10 ng/ml, 81% had levels below 20 ng/ml, and 96% had levels below 30 ng/ml. Notably, 25(OH)D levels did not differ by season or gender but were significantly higher among 164 hip fracture patients, with any vitamin D supplementation compared with 680 without supplementation (19.9 versus 10.8 ng/ml; p < 0.0001). CONCLUSION: Only about 20% of seniors receive vitamin D at the time of their fracture and after the event. This is despite the documented 81% prevalence of vitamin D deficiency. Interdisciplinary efforts may be warranted to improve vitamin D supplementation in seniors both before a hip fracture occurs and after.

Evoked potentials: modifications by classical conditioning.

Visual evoked potentials to a positive discriminative stimulus change systematically during sensory conditioning and extinction. Changes due to conditioning are manifested in the increased amplitude of the late component of the evoked response. This effect is attenuated during extinction and reappears after reconditioning.

Rana pipiens complex: hemoglobin phenotypes of sympatric and allopatric populations in Arizona.

Electrophoretic comparison of hemoglobin samples from numerous populations of Rana pipiens in Arizona reveals three distinct phenotypes that closely correlate with morphological differences. Hemoglobin samples from sympatric locations contain parental phenotypes with only the occasional occurrence of a hybrid. These data support the contention that the Rana pipiens complex consists of several species.

Treatment of Periprosthetic Femoral Fractures Vancouver Type B2: Revision Arthroplasty Versus Open Reduction and Internal Fixation With Locking Compression Plate.

INTRODUCTION: The Vancouver algorithm recommends revision arthroplasty (RA) for Vancouver type B2 (VTB2) fractures. However, open reduction and internal fixation (ORIF) using locking compression plates (LCP) may be a valid and less invasive alternative treatment. MATERIALS AND METHODS: Between January 2007 and March 2017, we retrospectively recruited all patients treated with either ORIF with LCP or RA for VTB2 fractures in our clinic. All of the following were reviewed: the length of hospital stay, the operating time, the need for blood transfusions during and/or after surgery, implant-related and patient-related complications, need for revision surgery, and the radiological outcome. Additionally, the functional outcome was investigated. RESULTS: Fifty-nine patients were recruited. Thirty-five (59.3%) patients underwent RA, while 24 (40.7%) patients received ORIF with LCP. The median surgical time was 137.50 minutes in the LCP group compared to 160.00 minutes in the RA group (P = .051). Three (12.5%) patients in the LCP group and 10 (28.6%) patients in the RA group experienced an implant-associated complication (P = .131). Patient-related complications occurred in 3 (12.5%) patients in the LCP group versus 6 (17.1%) patients in the RA group (P = .628). The mean preoperative Parker mobility score was 9 points in both groups and decreased in both groups to a mean of 5 points in the LCP and 7 points in the RA group. DISCUSSION: Open reduction and internal fixation with LCP seems to be a less invasive procedure for VTB2 fractures in comparison to RA. It is a bone-sparing procedure that can be advantageous for further revision operations. Moreover, some fractures can only be anatomically reduced by ORIF with LCP, whereas for proximal fractures with a radiologically unambiguously loosened stem RA might be advantageous. CONCLUSION: In line with previously published studies, our data suggest that ORIF using LCP is a valid treatment option for VTB2 fractures.

Severe vitamin D deficiency in Swiss hip fracture patients.

BACKGROUND: Most clinical guidelines for the prevention of hip fractures recommend 800 IU vitamin D per day. This dose shifted serum 25-hydroxyvitamin D levels (25(OH)D) in previous studies to between 60 and 100 nmol/l. AIM: To measure 25(OH)D levels and prevalence of vitamin D supplementation in individuals age 65+ with acute hip fracture. METHODS: 222 consecutive hip fracture patients were investigated over a 12 month period. Mean age of patients was 86 years and 77% were women. RESULTS: Mean serum 25(OH)D levels were low among hip fracture patients admitted from home (34.6 nmol/l), from assisted living (27.7 nmol/l), and from nursing homes (24 nmol/l). Severe vitamin D deficiency below 30 nmol/l was present in 60%, 80% were below 50 nmol/l, and less than 4% reached desirable levels of at least 75 nmol/l. Consistently, only 10% of hip fracture patients had any vitamin D supplementation on admission to acute care with significantly higher 25(OH)D levels among individuals supplemented with 800-880 IU/day (63.5 nmol/l). Controlling for age and gender, vitamin D supplementation, type of dwelling, and season were independently and significantly associated with 25(OH)D levels. CONCLUSION: These data provide evidence that current guidelines for the prevention of hip fractures need further effort to be translated into clinical practice.

Evaluation of critical incidents in general surgery.

BACKGROUND: The analysis of adverse events is a central step in critical incident reporting, but has not been described in a surgical setting. The aim of this study was to develop an evaluation protocol and assess its feasibility. METHODS: All incidents were analysed by a multidisciplinary team. A coding system based on three published theories was used to assess all incidents and their underlying causes. A risk analysis was also conducted. RESULTS: Between July 2004 and December 2005, 9785 inpatients were treated and 139 critical incidents reported. Classification of active errors revealed 47.7 per cent to be execution failures and 45.9 per cent knowledge-based errors. The distribution of medical errors was 12.9 per cent diagnostic, 46.0 per cent treatment, 17.3 per cent preventive and 23.7 per cent other. Some 282 latent failures were identified among the 139 incidents. Risk analysis revealed a severe incident rate of 21.6 per cent. CONCLUSION: This study has shown the feasibility of an evaluation protocol based on a combination of three classification systems and a risk analysis. It allows a thorough assessment of critical incidents, identification of priorities and tailored countermeasures.

[Complex fracture of the proximal humerus in the elderly. Locking plate osteosynthesis vs hemiarthroplasty]. / Komplexe proximale Humerusfraktur beim alten Menschen. Winkelstabile Plattenosteosynthese vs. Hemiarthroplastik.

BACKGROUND: The purpose of the present study was a direct comparison of fixed-angle plate fixation (FAPF) and shoulder hemiarthroplasty (SHA) for complex fractures of the proximal humerus in the elderly. PATIENTS AND METHODS: A single-institution case series of 52 consecutive geriatric patients (age > or =70 years) treated with FAPF for three- and four-part fractures of the proximal humerus between 2003 and 2005 was analysed 1 year after surgery. The analysis included Constant Score (CS), Oxford Shoulder Score (OSS), and radiological evaluation. Outcome was compared with a similar historic group of patients (n=59) who received SHA in an earlier period (1995--1997). RESULTS: The patient groups showed no differences in age, gender, or fracture type. Median CS was significantly better for FAPF (71 vs 41). Evaluation of pain demonstrated no differences between the two treatment modalities in the OSS. Revision surgery was performed more often in the FAPF group (25% vs 2%). CONCLUSION: Compared to SHA, functional outcome was superior with FAPF. However, this was associated with a higher rate of revision surgery. Most patients were still able to live independently in their original environment, regardless of the type of surgery.

[Combined dorsal and palmar plate osteosynthesis for intraarticular distal radius fractures]. / Kombinierte dorsale und palmare Plattenosteosynthese bei distalen intraartikulären Radiusfrakturen.

BACKGROUND: Complex comminuted intraarticular fractures of the distal radius require anatomic restoration. In rare cases, this aim can only be achieved by a combined dorsal and volar plate fixation despite increasing experience with volar locking compression implants. This retrospective quality control study investigated functional, radiological and subjective outcomes of patients treated with this technique. METHODS: Between March 1999 and January 2003, 30 out of 360 patients who were operated on for an unstable distal radius fracture with complex C2/C3 type distal radius fractures at the Division of Trauma Surgery of the University Hospital Zurich, had been treated with a combined dorso-palmar plate fixation (dorsal two 1/4 tubular plates, volar 3.5 mm T-plate) and were included in this study (9 female, 21 male, mean age 52 years). Of the 30 patients 25 could be evaluated at an average of 29 months after injury. RESULTS: Anatomic reconstruction could not be achieved in all cases, 56% showed mild and 28% explicit signs of arthrosis. Flexion reached 66% and extension 75% of the contralateral wrist, whereas pronation reached 98% and supination 91%, respectively. Grip strength achieved 75% of that of the contralateral side and 10 patients (40%) developed a complex regional pain syndrome (CRPS). Return to work was possible 120 days after the injury. CONCLUSION: With the dorso-palmar plate fixation joint reconstruction in complex intraarticular distal radius fractures can be achieved with a satisfactory subjective, functional, and radiologic result, although additional soft tissue injury was caused by the bilateral approach. The patient has to be informed of the high rate of CRPS and the long period of disability.

Evaluation of radiographic fracture position 1 year after variable angle locking volar distal radius plating: a prospective multicentre case series.

Treatment with a variable angle locking plate can, in theory, maintain near anatomic reduction of intra-articular distal radius fractures, but it is unknown to what extent reduction is maintained as measured by computed tomography. We assessed changes in radiographic fracture position 1 year post-operatively. We included 73 patients of whom 66 patients (90%) had radiographs available for review at 1 year post-operatively. We found a small (less than 2 mm or 2°) but statistically significant change in several measures. Accounting for inter-observer variability, this is probably within measurement error. We found no difference in change in fracture position or range of motion, grip strength or patient-reported outcome between the use of one or two distal rows of screws. Our results show that minimal changes in reduction can be expected after volar plate fixation in most patients. We recommend using only one screw row routinely, limiting costs, surgical time and the risk of misplacement of screws. LEVEL OF EVIDENCE: IV.

Screening of germline mutations in the CDKN2A and CDKN2B genes in Swedish families with hereditary cutaneous melanoma.

BACKGROUND: Approximately 10% of human cutaneous melanomas occur in families in which several members are affected. The familial predisposition to this disease is often associated with dysplastic nevus syndrome, a condition in which afflicted family members have multiple dysplastic nevi (atypical moles). The chromosome region 9p21 and markers on chromosomes 1p and 6p have been linked to melanoma susceptibility. The tumor suppressor genes CDKN2A and CDKN2B have been mapped to the 9p21 region, and genetic analyses have revealed the presence of germline CDKN2A alterations in melanoma families. The reported frequencies of such alterations, however, vary among these families. PURPOSE: The present investigation was carried out to determine the frequencies of CDKN2A and CDKN2B germline gene mutations among members in a population-based cohort of Swedish melanoma families (i.e., melanoma kindreds). METHODS: DNA was prepared from blood samples obtained from 181 individuals belonging to 100 melanoma kindreds. The polymerase chain reaction (PCR) technique, followed by single-strand conformation polymorphism (SSCP) and nucleotide sequence analyses, were used to identify the types and frequencies of mutations in exons 1, 1beta, 2, and 3 of the CDKN2A gene and in exons 1 and 2 of the CDKN2B gene. RESULTS: CDKN2A gene aberrations were independently identified by both SSCP and nucleotide-sequence analyses. Nucleotide-sequence analysis identified a single point mutation leading to a substitution of leucine for proline in codon 48 of exon 1 in a family with a history of melanoma and several other cancers. A second abnormality, leading to an insertion of an extra arginine residue at codon number 113 of exon 2, was seen in four separate families. The CDKN2A exon-3 coding region had the wild-type sequence in all samples. No germline mutations were found in the alternative exon 1beta of the CDKN2A gene or in exons 1 and 2 of the CDKN2B gene. CONCLUSIONS: The present investigation demonstrates that CDKN2A germline gene mutations were observed in 7.8% of the 64 Swedish melanoma kindreds that each included at least two first-degree relatives with melanoma and dysplastic nevus syndrome. No CDKN2A exon 1beta or CDKN2B mutations were identified. The critical genes responsible for the inheritance of a susceptibility to develop melanoma among family members in this population have yet to be identified.

CDKN2A germ-line mutations in individuals with multiple cutaneous melanomas.

Germ-line CDKN2A mutations are present in some kindreds with hereditary cutaneous melanoma, and in Sweden a founder mutation with an extra arginine in codon 113 (113insR) has been identified. We screened 80 individuals with at least two primary cutaneous melanomas, who were identified mainly by a search of a regional cancer registry, for germ-line CDKN2A mutations. In nine patients, CDKN2A alterations that may contribute to melanoma predisposition were detected. In six individuals with a family history of melanoma, the 113insR founder mutation was present. One patient, who also had a family history of melanoma, had a 24-bp deletion that included codons 62-69. An in vitro binding assay established that the resulting mutant p16 protein was unable to bind cyclin-dependent kinase 4 and cyclin-dependent kinase 6. Two patients without a family history of melanoma had CDKN2A alterations: (a) one had a mutation in the 5' noncoding sequence (-14C/T); and (b) the other had an insertion of an extra T in codon 28, which results in a stop signal in codon 43. The median age at diagnosis of the first melanoma was significantly lower, the number of primary melanomas was significantly higher, and the presence of a family history of melanoma was significantly more common in patients with CDKN2A mutations than in those without germ-line mutations. The proportion of CDKN2A mutation carriers was significantly higher among patients treated for three or more primary melanomas compared with those with two tumors only. We conclude that mutation screening of individuals with multiple primary melanomas is a useful strategy to identify new melanoma kindreds with CDKN2A germ-line mutations.

Novel O6-methylguanine-DNA methyltransferase SNPs: a frequency comparison of patients with familial melanoma and healthy individuals in Sweden.

The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) is involved in the cellular defense against alkylating agents. Genetic alterations in the MGMT gene may impair the protein's ability to remove alkyl groups from the O6-position of guanine, thereby raising the mutation rate and increasing the risk of cancer. We assessed polymorphisms in the promoter region and the 5 exons of the MGMT gene by PCR/SSCP and nucleotide sequence analysis of DNA extracted from blood samples. The population studied consisted of 89 melanoma patients, each belonging to a different family with a hereditary predisposition for melanoma, and 76 healthy individuals (blood donors). A total of 11 single nucleotide polymorphisms (SNPs) were detected, five in the promoter region, one in exon 1, two in exon 3 and three in exon 5. Six of the alterations were novel polymorphisms, of which five were located in the promoter region and one in exon 5. When the distribution of specific SNPs in cases and controls with only one variant was calculated; C575A was present only in melanoma patients (p=0.072). Moreover, while 20% of the healthy individuals had no SNPs this was the case in only 12.4% of the melanoma patients. However, no statistically significant differences were seen between cases and controls for any of the 11 SNPs.

N-ras mutations are common in melanomas from sun-exposed skin of humans but rare in mucosal membranes or unexposed skin.

Ras mutations, preferentially in codon 61 of the N-ras oncogene, are common in human cutaneous melanomas. In this study, we questioned the association between ras mutations in primary melanomas and sun exposure. DNA was extracted from formalin-fixed primary melanomas: 28 at chronically sun-exposed head and neck areas, 18 at sites subject to intermittent sun exposure, and 28 from unexposed mucosal membranes (vulva/vagina, anus/ rectum, palate). Mutations of both exons of H-, K-, and N-ras genes were examined by polymerase chain reaction/single-strand conformation polymorphism and by direct nucleotide sequencing of the polymerase chain reaction amplified exons. Thirty-two per cent of the head and neck melanomas and 11% of the melanomas from intermittently sun-exposed skin had N-ras codon 61 mutations; comparatively only 7% of the tumors from the unexposed areas had such mutations. One vulvar melanoma had an N-ras codon 12 mutation. No H-ras or K-ras mutations were detected in any sample. The frequency of N-ras exon 2 mutations in melanomas of typically sunbathed skin was compared for the first time with that in melanomas of areas completely protected from sun exposure. The significantly higher frequency (p = 0.04, chi square exact test) of these N-ras mutations on the head and neck demonstrates their UV-light induction in a subset of melanomas explaining one of the molecular effects of UV light in human skin.

Transthyretin messenger ribonucleic acid expression in the pancreas and in endocrine tumors of the pancreas and gut.

Transthyretin (TTR) cDNA probes were used to determine the presence of TTR mRNA in Northern blots from rat, porcine, and human organs as well as from human endocrine tumors. We also used in vitro translation in our study of the human tissues. In accordance with previous findings, TTR mRNA was found in the choroid plexus and, to a lesser extent, in the liver of all three species. In addition low levels of TTR mRNA were identified in the rat and human pancreas. All of the endocrine pancreatic tumors (two glucagonomas, two insulinomas, and one nonfunctional tumor) and the gut carcinoid also contained TTR mRNA, whereas other endocrine tumors (two pheochromocytomas and one paraganglioma) and one adenocarcinoma of the pancreas were TTR mRNA negative. The level of TTR mRNA expression in most of the endocrine pancreatic tumors exceeded that in the liver. The in vitro translations produced pre-TTR molecules of similar size for all TTR mRNA-positive human organs and tumors.

Analysis of O6-methylguanine-DNA methyltransferase mRNA in fine needle biopsies from human melanoma metastases by reverse transcription and polymerase chain reaction.

O6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein, which removes alkyl groups from the O6 atom of guanine residues. Tumour cells which lack MGMT are sensitive to cytostatic drugs such as dacarbazine (DTIC), whose active species bind to this site. To explore whether analyses of MGMT expression can be used as a predictive test for clinical sensitivity to DTIC in melanomas, we developed a method to assay MGMT mRNA levels in cells obtained by fine needle aspiration biopsies of metastases. cDNA was synthesised from mRNA prepared from biopsy material. Polymerase chain reaction was performed using primers complementary to MGMT cDNA and to beta-actin, which served as an internal control. Analyses of 44 biopsies from 35 patients showed a considerable variation in MGMT mRNA, with 15 samples (34%) lacking detectable mRNA. In 6 out of 8 patients in whom more than one tumour was analysed, separate metastases had different levels of MGMT mRNA. There was no correlation between MGTM activity studied by a biochemical assay and MGMT mRNA levels when these were compared in 10 surgical biopsies.

Melanoma development in relation to non-functional p16/INK4A protein and dysplastic naevus syndrome in Swedish melanoma kindreds.

The CDKN2A gene encodes the cell cycle inhibitor p16/ INK4A, which is involved in familial cutaneous melanoma. We have studied five Swedish familial melanoma kindreds characterized by germline mutations in CDKN2A and dysplastic naevus syndrome (DNS). We found significant correlations between germline CDKN2A mutations and melanoma and between DNS phenotype and melanoma, respectively. There was also a correlation between mutation status and the presence of DNS. In CDKN2A mutation carriers, all cases of early-onset melanoma occurred in DNS individuals, and the mean age at melanoma diagnosis was significantly lower in individuals with DNS than in those without a confirmed DNS phenotype. In one family where the proband had a P48L mutation in CDKN2A exon 1, the DNS phenotype was studied in detail. In vitro binding experiments established that the P48L mutant protein does not bind to cdk4 or cdk6 and thus is functionally abnormal. Furthermore, we demonstrated loss of heterozygosity at markers on chromosome 9p flanking the CDKN2A locus in a primary melanoma and a metastasis from the proband. Our results are consistent with the hypothesis that germline CDKN2A mutations and DNS both contribute to the predisposition to melanoma and may lead to the development of early-onset melanoma when present in the same individual.

Immunohistochemical analysis of the N-ras p21 and the p53 proteins in naevi, primary tumours and metastases of human cutaneous malignant melanoma: increased immunopositivity in hereditary melanoma.

Immunohistochemical analysis of the N-ras p21 and the p53 proteins was carried out on formalin-fixed sections of naevi, primary melanomas and metastases from patients with sporadic melanoma (SCMM) and with hereditary melanoma (HCMM)/dysplastic naevus syndrome (DNS). Seven out of 11 (64%) common naevi and three out of nine (33%) dysplastic naevi showed increased cytoplasmic N-ras expression. No p53 immunopositivity could be recognized in any of the naevus samples. However, strong N-ras expression as well as immunopositivity for p53 was recognized among primary melanomas and metastases with significantly higher frequency among samples from patients with HCMM compared with samples from SCMM cases (for N-ras, 40% vs 10%, P < 0.01; and for p53 43% vs 17%, P < 0.05). We have earlier registered N-ras codon 61 mutations among metastases from 59% of patients with HCMM and from 24% of subjects with SCMM. A comparison of the genetic data with the immunohistochemical results showed occurrence of increased N-ras p21 expression in the presence and absence of detectable N-ras mutant alleles. Increased expression of wildtype N-ras p21 may contribute to tumorigenicity in the absence of mutational activation, at least in a subset of melanomas. Altogether, N-ras p21 alterations are registered at earlier stages than p53 alterations in melanoma development and may be of aetiological importance, whereas p53 alterations may be associated with tumour progression in the late stages.(ABSTRACT TRUNCATED AT 250 WORDS)

Melanoma metastases from patients with hereditary cutaneous malignant melanoma contain a high frequency of N-ras activating mutations.

Mutations in N-ras exon 2 codon 61 were studied in formalin-fixed human melanoma metastases. DNA fragments including codon 61 were amplified by polymerase chain reaction (PCR) and mutational analysis was performed by oligonucleotide hybridization (ODN), allele specific PCR and PCR combined with single strand conformation polymorphism analysis (SSCP). Thirty metastases from 25 patients with 'spontaneous' cutaneous melanoma were compared with 35 metastases from 17 patients with 'hereditary' cutaneous melanoma. The frequency of mutations as measured by PCR/ODN was significantly higher in patients with hereditary melanoma (mutations in 24% versus 59%, p < 0.05). The most frequent mutations were C/A transversions to lysine (AAA). The occurrence of lysine mutations was, in addition, studied by allele specific polymerase chain reaction. Again, the mutation frequency was significantly higher in metastases from patients with hereditary melanoma. PCR/SSCP finally enabled the isolation of lysine mutant alleles and nucleotide sequence analysis which confirmed the presence of the mutated codon 61. The relatively higher frequency of N-ras mutations in tumours from patients with hereditary melanoma may be related to the hypermutability described in hereditary melanoma and dysplastic naevus syndrome. The results support an involvement of N-ras mutations in the molecular pathogenesis of melanoma.