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Biomedical subjects

S M Hou

Publications and source records attributed to S M Hou.

At least 37 records · Page 2Linked to original sources
PubMed2000

Rotational alignment of humerus after closed locked nailing.

OBJECTIVE: Rotational malalignment that may happen during closed nailing of humeral fractures is, to date, an unexplored area of investigation. The purpose of this study was to examine the effect of arm position during surgery on humeral rotational alignment and the effect of this alignment on shoulder motion and function. METHODS: Thirty patients with eventual fracture healing after closed humeral locked nailing were retrospectively studied: 15 had retrograde nailing; 15, antegrade. Retrograde nailing was performed with the patient in a decubitus position and with the upper arm anteriorly flexed and the forearm perpendicular to the operating table. Antegrade nailing was performed with the patient in a semisitting position and with the upper arm in the so-called resting position. The humeral retroversion angle as measured by computed tomographic scan, range of shoulder rotation, and Neer score of the shoulder for the fractured and the intact humeri were determined, and the discrepancy (i.e., value for the intact subtracted from that for the fractured) between the two was noted. To test the effect on alignment of positioning during retrograde nailing, we similarly determined retroversion angles for another 15 patients treated in a supine resting position. RESULTS: Between antegrade nailing and retrograde nailing in decubitus position, there was a significant difference in the mean discrepancies for the retroversion angles and the range of external rotation of the shoulder in the neutral and abduction positions, but no significant difference for internal rotation of the shoulder and Neer score. Between antegrade nailing and retrograde nailing in supine resting position, there was no significant difference in the mean discrepancy for the retroversion angle. CONCLUSION: Positioning of the arm may significantly affect humeral rotational alignment and range of motion during closed nailing. Until a reliable method for intraoperative measurement of humeral rotation is devised, we recommend that closed nailing of humeral shaft fractures be performed with the patient's upper arm in the resting position shown in this study.

Adolescent↗
PubMed2000

A functional model for whole limb transplantation in the rat.

To develop a functional model for the study of whole limb transplantation, inbred Lewis rats were used as both donors and recipients. In this model, the recipient biceps femoris muscle was elevated from its distal attachment to preserve part of the adductor function of the limb after surgery. The tibial, peroneal, and sural branches of the sciatic nerve were anastomosed separately to provide faster and more precise functional recovery. For control sensory evaluation, the saphenous branches of the femoral nerve were not reattached. A flat intramedullary pin stabilized with methyl methacrylate was used to rigidly immobilize the femur. The transplanted limbs started bearing weight at 17 to 22 days. Walking on the plantar surface of the hock and adduction of the toes gradually decreased, and the rats developed a normal walking pattern. Sciatic and tibial function indexes, based on walking track analysis, correlated well with clinical observations. In this study, a new model for limb transplantation was developed that provided good and reliable sensory and ambulatory recovery.

Animals↗
PubMed2000

Mycobacterial infection of the upper extremities.

BACKGROUND AND PURPOSE: Mycobacterial infection of the upper extremities is extremely rare. To make an early accurate diagnosis is often difficult, and the treatment is, therefore, frequently delayed in clinical practice. This paper describes the diagnosis and treatment of mycoabacterial infection of the upper extremities in a series of patients treated at National Taiwan University Hospital. METHODS: The medical records of 15 patients with mycobacterial infection of the upper extremities treated between 1985 and 1998 were retrospectively analyzed. The diagnosis of mycobacterial infection was established by positive culture results, the presence of acid-fast bacilli, or characteristic histopathologic findings. RESULTS: Mycobacterial infection was suspected on initial examination in only two patients. The duration between the onset of symptoms and correct diagnosis averaged 37.5 months (range, 3 wk to 209 mo). The involved sites of mycobacterial infection included the wrist in nine patients, the elbow in two, the hand in two, the humerus in two, the forearm in one, and the shoulder in one. Three patients suffered from multifocal musculoskeletal mycobacterial infection. Microbiologic studies identified Mycobacterium tuberculosis in four patients and nontuberculous mycobacteria (NTM) in four. Characteristic histopathologic findings of mycobacterial infection including caseation, granulomatous inflammation, eosinophilic epithelioid cells, Langhan's giant cells, and lymphocytic aggregates were noted in all 15 patients. All patients received chemotherapy and 14 patients underwent surgical treatment. The mean duration of follow-up was 46 months (range, 15-97 months). Treatment failed in two of the patients with multifocal NTM infection and in one patient whose mycobacterial infection was identified by histopathology. CONCLUSIONS: Mycobacterial infection should be included in the differential diagnosis of infection of the upper extremities. Treatment failures are more frequent in patients with multifocal NTM infection.

Adolescent↗
PubMed2000

Ipsilateral distal radius and scaphoid fractures.

Simultaneous fractures of the distal radius and scaphoid are uncommon. Previous reports have outlined a variety of treatment methods for this condition. We describe the results in eight patients with simultaneous fractures of the distal radius and scaphoid, who were treated at National Taiwan University Hospital from 1987 to 1998. Treatments for the distal radius fractures included pin-in-cast in one patient, casting in one, external fixation in one, external fixation after pinning in three, and open reduction with internal fixation in two. All scaphoid fractures occurred at the scaphoid waist, and were treated with long-arm thumb spica in three patients, Herbert screw fixation in two, and percutaneous pinning in three. All of the fractures united, and none of the patients developed scaphoid avascular necrosis. One patient suffered from superficial radial nerve injury during external fixation. The functional results of the wrist were good in five patients and fair in three. To prevent the possible over-distraction of the scaphoid fracture, fixation of the scaphoid should be performed if a distraction force is to be applied during the treatment of the distal radius fracture. If no distraction force is to be applied, a thumb spica may provide adequate fixation for the scaphoid fracture.

Adult↗
PubMed1999

Validation of the human T-lymphocyte cloning assay--ring test report from the EU concerted action on HPRT mutation (EUCAHM).

The T-cell cloning assay, which enables the enumeration and molecular analysis of 6-thioguanine resistant (HPRT-negative) mutant T-cells, has been extensively used for studying human somatic gene mutation in vivo. However, large inter-laboratory variations in the HPRT mutant frequency (MF) call for further investigation of inter-laboratory differences in the experimental methodology, and development of an optimal but easy uniform cloning protocol. As part of the EU Concerted Action on HPRT Mutation (EUCAHM), we have carried out two Ring tests for the T-cell cloning assay. For each test, duplicate and coded samples from three buffy coats were distributed to five laboratories for determination of MF using six different protocols. The results indicated a good agreement between split samples within each laboratory. However, both the cloning efficiencies (CEs) and MFs measured for the same blood donors showed substantial inter-laboratory variations. Also, different medium compositions used in one and the same laboratory resulted in a remarkable difference in the level of MF. A uniform operating protocol (UOP) was proposed and compared with the traditional protocols in the second Ring test. The UOP (preincubation) increased the CE in laboratories traditionally using preincubation, but decreased the CE in laboratories traditionally using priming. Adjusted for donor, use of different protocols contributed significantly to the overall variation in lnCE (P = 0.0004) and lnMF (P = 0.03), but there was no significant laboratory effect on the lnCE (P = 0.38) or lnMF (P = 0.14) produced by the UOP alone. Finally, a simplified version of the UOP using the serum-free medium X-Vivo 10 and PMA was tested in one laboratory, and found to produce a considerable increase in CE. This modified UOP needs to be further evaluated in order to be used for future databases on HPRT MFs in various populations.

Clone Cells↗
PubMed1999

Influence of smoking and donor age on the spectrum of in vivo mutation at the HPRT-locus in T lymphocytes of healthy adults.

Types and frequencies of in vivo mutation in the hypoxanthine-guanine phosphoribosyl-transferase (HPRT) gene was studied in 142 T cell mutants from 78 healthy nonsmoking and smoking adults with a mean of 65 years. The HPRT mutant frequency in the nonsmokers was 18.7 +/- 12.0 x 10(-6), and in the smokers 26.6 +/- 18.5 x 10(-6) (mean +/- S.D., P < 0.01). Among 107 single base pair substitutions (SBS) in the coding region of the HPRT gene, one new mutable site, one novel nonsense mutation and three not previously reported SBS were identified. Transitions accounted for 59% of the SBS and transversions for 41%. GC > AT transitions were the predominant type of mutation, with 50% of all SBS. The mutations showed a nonrandom distribution along the coding sequence, with three significant hotspots at positions 143, 197 and 617 (13, 14 and 7 mutations, respectively). There was no difference between smokers and nonsmokers with regard to the distribution of mutations at these hotspot positions. However, 85% of the mutations at GC base pairs and 88% of the mutations at AT base pairs in smokers occurred at sites with guanine or thymine, respectively, in the nontranscribed DNA strand. Moreover, smokers had a higher frequency of transversions and lower frequency of transitions than nonsmokers did. Particularly, GC > TA transversions were increased in smokers (11%) compared to nonsmokers (2%), which suggests that tobacco-smoke induced adducts at guanine bases in the nontranscribed DNA strand contributes to the increase of HPRT mutation in smokers. Overall, these results were very similar to the mutational spectra in two younger study populations reported previously [K.J. Burkhart-Schultz, C.L. Thompson, I.M. Jones, Spectrum of somatic mutation at the hypoxanthine phosphoribosyltransferase (HPRT) gene of healthy people, Carcinogenesis 17 (1996) 1871-1883; A. Podlutsky, A.-M. Osterholm, S.-M. Hou, A. Hofmaier, B. Lambert, Spectrum of point mutations in the coding region of the hypoxanthine-guanine phosphoribosyltransferase, Carcinogenesis 19 (1998) 557-566]. With the possible exception of an increase of mutations at hotspot position 143, and a decrease of 5-methylcytosine deamination mediated transitions at CpG-sites in the older individuals, there were no differences between the mutational spectra of old and young adults. In conclusion, both smoking and ageing seem to have minor influences on the spectrum of HPRT mutation in T cells.

Adult↗
PubMed1999

Antioxidant status following acute ischemic limb injury: a rabbit model.

Although ischemic injury to skeletal muscle is a matter of great clinical importance, relatively little is known about the mechanisms which determine systemic responses. One purpose of this study is to elucidate the systemic antioxidant status following an episode of acute ischemic limb injury and subsequent reperfusion. Twelve New Zealand white rabbits were used in this study. After the animals were anesthetized, an ischemic insult was created in the right hind limb for twelve hours, followed by four hours of reperfusion. Several series of blood samples were obtained. At the end of the experiment, the animals were killed and necropsies undertaken in order to evaluate the antioxidant status of various visceral organs. The results link ischemia and reperfusion injury to a significant decline in antioxidative activity in various tissues. The weakening in antioxidant status after ischemic limb injury was most pronounced in the heart tissue, followed in descending order by the spleen, skeletal muscle, lung, liver, and kidney tissue. The levels of specific antioxidants and reactive oxygen species in various organs changed significantly, and the changes were tissue specific. Endogenous radical scavenging systems were not entirely overwhelmed in most of the tissues studied. But higher levels of malondialdehyde (MDA) found in cardiac tissue suggest that the production of oxygen free radicals is accelerated by an ischemic injury. Based on the study, we believe that the cardiac tissue is particularly susceptible to the effects of ischemia and reperfusion injury. Damage to cardiac tissue is probably the major cause of mortality following acute ischemic injury in a limb.

Animals↗
PubMed1999

Hprt mutant frequency and aromatic DNA adduct level in non-smoking and smoking lung cancer patients and population controls.

T cell cloning and 32P-post-labelling methods were used to study the mutant frequency (MF) at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus and the aromatic DNA adduct level (AL) in peripheral lymphocytes of newly diagnosed lung cancer patients (92 ever-smokers and 87 never-smokers) and matched population controls (82 ever-smokers and 79 never-smokers). Overall, the MF (total mean 20.6 x 10(-6)) and AL (4.1 x 10(-8)) were similar in cases and controls with the same smoking status, indicating that the disease has limited effect on the two endpoints. When cases and controls were combined, the AL was significantly higher in current smokers than in former or never-smokers (P = 0.0003) and the MF was significantly higher in ever-smokers than in never-smokers (P = 0.004). Age affected the MF significantly in ever-smokers (1.6%/year, 95% CI 0.6-2.5, adjusted for pack-years and years since last smoking), especially among cases (2.1%/year, 95% CI 0.5-3.7). An increase of AL with age was observed in currently smoking cases only (2.3%/year, 95% CI 0.3-4.2, adjusted for smoking dose). For currently smoking cases, there was also a more pronounced effect of smoking dose on both endpoints and a significant correlation between AL and MF (r = 0.52, P = 0.04) was observed among those with the highest dose. Our data also provide additional evidence for the different turnover times of smoking-induced DNA adducts and hprt mutations. The stronger increase of MF and AL with age and dose in currently smoking patients compared with controls is consistent with an interaction between smoking and genetic host factors.

Adenocarcinoma↗
PubMed1999

Antegrade locked nailing for humeral shaft fractures.

Treatment results of antegrade locked nailing of acute humeral shaft fractures, including union rate and recovery of shoulder function, have been inconsistent. This led the current authors to hypothesize that implant design and surgical techniques might account for this inconsistency. In the current study, 47 fractures (38 acute; nine pathologic) in 47 patients achieved union with the techniques of closed nailing, short to long segment nailing, and fracture compression. Satisfactory recovery of shoulder function occurred because of minimal surgical trauma, prevention of impingement by the nail or locking screws, and prevention of axillary nerve injury or comminution of the humeral head. Forty-seven patients with 38 acute fractures and nine pathologic fractures were treated with humeral locked nails. Mean followup time was 21.4 months. With a single operation, all 38 acute fractures proceeded to eventual union; the average time to union was 7.8 weeks. Thirty-five patients had excellent or satisfactory recovery of shoulder function. Complications included slipout of the proximal screw, nail breakage, fragment displacement, and transient postoperative radial nerve palsy. All nine patients with pathologic fractures had substantial pain relief and increased arm function after surgery. The current study shows the reliability of antegrade locked nailing for proximal and middle third fractures of the humeral shaft.

Adult↗
PubMed1999

Influence of genetic polymorphisms of biotransformation enzymes on gene mutations, strand breaks of deoxyribonucleic acid, and micronuclei in mononuclear blood cells and urinary 8-hydroxydeoxyguanosine in potroom workers exposed to polyaromatic hydrocarbons.

OBJECTIVES: Airborne exposure to polycyclic aromatic hydrocarbons (PAH) in the potroom of an aluminum reduction plant was studied in relation to genotoxic or mutagenic effects, and the possibility of host genotypes of different metabolizing enzymes modifying associations between PAH exposure and genotoxic or mutagenic response was assessed. SUBJECTS AND METHODS: Ninety-eight male potroom workers and 55 male unexposed blue-collar workers constituted the study population. Micronuclei in CD4+ and CD8+ lymphocytes, DNA (deoxyribonucleic acid) single-strand breaks, hypoxanthine guanine phosphoribosyl transferase (HPRT) mutation frequency, and genotype for cytochrome P-4501A1, glutathione transferases M1, T1 and P1, and microsomal epoxide hydrolase were analyzed using peripheral mononuclear cells. Urine samples were collected for the analysis of 8-hydroxydeoxyguanosine. RESULTS: Micronuclei in peripheral CD4+ and CD8+ lymphocytes, DNA single-strand breaks, HPRT mutation frequency, and 8-hydroxydeoxyguanosine in urine did not differ between the potroom workers and the unexposed referents. With the exception of an observed exposure-response relationship for potroom workers with Tyr/Tyr genotype for microsomal epoxide hydrolase, between airborne PAH and CD8+ micronuclei, no correlations were found between any of the genotoxicity biomarkers and any of the exposure measures (airborne particulate PAH, airborne gas phase PAH, length of employment in the potroom, 1-hydroxypyrene in urine, or PAH-DNA adducts in peripheral lymphocytes), also when genotypes for biotransforamtion enzymes were considered. CONCLUSIONS: The results indicate that the employed biomarkers of mutagenic or genotoxic effects are not appropriate for surveillance studies of potroom workers exposed to current airborne levels of PAH. The significance of the correlation between airborne PAH and CD8+ micronuclei in Tyr/Tyr genotype subjects should be evaluated.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Anatomic considerations of locked humeral nailing.

To investigate the risk of axillary nerve injury by the proximal locking screws in antegrade nailing of humeral fractures, the anatomy of the axillary nerve was examined in 20 fresh anatomic specimen humeri, which subsequently were nailed antegrade with specially designed humeral locked nails. The axillary nerve was found to be on average 45.6 mm below the tip of the greater tuberosity; it was jeopardized by insertion of the lower proximal locking screw in one of the 20 specimens. Short humeri, humeri with small heads, or too deeply inserted nails may increase the risk of nerve injury; likewise, a lower location and more horizontal direction of the locking screws and a greater curvature of the nail can heighten the risk. In addition to the examination of the axillary nerve, a geometric study of these anatomic specimen was performed and was aimed at improving retrograde nailing technique and thus treatment results. The humeral geometry indicated that for the best linearity in the sagittal plane, an entry portal incorporating the superior margin of the olecranon fossa would be recommended for the 14 humeri with a distal humeral offset less than 4 mm, whereas a supracondylar entry portal would be recommended for the six humeri with an offset larger than 4 mm. For best linearity in the coronal plane, the entry portal and nailing direction should be more lateral in humeri with a smaller humeral elbow angle.

Aged↗
PubMed1999

Impact of medical informatics on medical education.

In recent years, medical informatics has become a well-recognized branch of medicine. It is a multidisciplinary science that combines information technology and various specialties of medicine. The impact of medical informatics on medical education is advancing along with the rapid developments in computer science. Departments of medical informatics or similar divisions have appeared in schools of medicine in Taiwan in the past 5 years. At National Taiwan University College of Medicine, we offer curricula in basic computer concepts, network concepts, operating systems, word processing, database and data processing, computer media resources, multimedia computer statistics, intelligent health information systems, medical diagnostic support systems, and electronic medical record systems. Distance learning has also been favorably accepted on this campus. Recently, we proposed the concept of a virtual medical campus, which will break the physical barriers of time and space. We expect this revolution to influence every aspect of medicine, especially medical education.

Education, Medical↗
PubMed1999

Recent advances in telemedicine.

With continuing advances in information technology, the applications of computers in medicine are increasing rapidly. Modern information technology not only affects the delivery of health care, but also significantly influences the doctor-patient relationship. Since the 1990s, technologic developments in high-bandwidth telecommunications systems and digitizing devices have led to a surge of interest in telemedicine. In recent years, the Internet, with its powerful penetration and scalability, has become an increasingly popular medical information resource and a new platform for telemedicine. The impact of modern technology on the advancement of telemedicine in Taiwan started with the 1995 National Information Infrastructure project, which uses networks of different bandwidths for teleconsultation and distance education programs. In 1998, National Taiwan University and Taipei Medical College in Taiwan, and the University of Pittsburgh and the University of Iowa in the USA, began cooperation on a new Cyber Medical Center (CMC) project that integrates the technologies of multimedia, database management, a multiple-site videoconferencing system, and the World Wide Web. The aim of the CMC is to create a multimedia network system for the management of electronic patient records, teleconsultation, online continuing medical education, and information services on the Web. In the future, telemedicine systems in Taiwan are expected to combine the Internet and cable television to connect clinics, hospitals, insurance organizations, and public health administrations; and, finally, to extend health services to every household.

Humans↗
PubMed1998

Molecular characterization of two deletion events involving Alu-sequences, one novel base substitution and two tentative hotspot mutations in the hypoxanthine phosphoribosyltransferase (HPRT) gene in five patients with Lesch-Nyhan syndrome.

Mutations identified in the hypoxanthine phosphoribosyltransferase (HPRT) gene of patients with Lesch-Nyhan (LN) syndrome are dominated by simple base substitutions. Few hotspot positions have been identified, and only three large genomic rearrangements have been characterized at the molecular level. We have identified one novel mutation, two tentative hot spot mutations, and two deletions by direct sequencing of HPRT cDNA or genomic DNA from fibroblasts or T-lymphocytes from LN patients in five unrelated families. One is a missense mutation caused by a 610C-->T transition of the first base of HPRT exon 9. This mutation has not been described previously in an LN patient. A nonsense mutation caused by a 508C-->T transition at a CpG site in HPRT exon 7 in the second patient and his younger brother is the fifth mutation of this kind among LN patients. Another tentative hotspot mutation in the third patient, a frame shift caused by a G nucleotide insertion in a monotonous repeat of six Gs in HPRT exon 3, has been reported previously in three other LN patients. The fourth patient had a tandem deletion: a 57-bp deletion in an internally repeated Alu-sequence of intron 1 was separated by 14 bp from a 627-bp deletion that included HPRT exon 2 and was flanked by a 4-bp repeat. This complex mutation is probably caused by a combination of homologous recombination and replication slippage. Another large genomic deletion of 2969 bp in the fifth patient extended from one Alu-sequence in the promoter region to another Alu-sequence of intron 1, deleting the whole of HPRT exon 1. The breakpoints were located within two 39-bp homologous sequences, one of which overlapped with a well-conserved 26-bp Alu-core sequence previously suggested as promoting recombination. These results contribute to the establishment of a molecular spectrum of LN mutations, support previous data indicating possible mutational hotspots, and provide evidence for the involvement of Alu-mediated recombination in HPRT deletion mutagenesis.

Alu Elements↗
PubMed1998

Integrated medical informatics with small group teaching in medical education.

National Taiwan University College of Medicine (NTUCM) introduced small groups of teaching and basic-clinical integrated courses for medical students in 1992. By using computer network and multimedia techniques, this study tried to overcome barriers to learning in small group teaching. The Department of Medical Informatics of NTUCM established campus networking and computer classrooms and provided Internet and intranet network services including mail, netnews, bulletin board systems (BBS), world wide web (WWW), gopher, ftp and local file servers. To implement an interactive learning environment, the authors first tried mail lists, newsgroups and BBS. Next an integrated learning system prototype on the WWW was developed to provide functions including online syllabus, discussion boards simulated to BBS, online talk, interactive case studies, virtual classroom with video on demand (VOD) and Internet medical resources. The results showed that after the medical students completed the required course of medical informatics and had good network access using a network to communicate with each other became a daily practice. In the future, the system will extend to the tutoring of clinical practice and continuing medical education. The authors expect a national medical education network and more international cooperation and exchange.

Curriculum↗
PubMed1998

Spectrum of point mutations in the coding region of the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene in human T-lymphocytes in vivo.

The hypoxanthine-guanine phosphoribosyl transferase (hprt) locus in 6-thioguanine (TG) resistant T-lymphocytes is a useful target for the study of somatic in vivo mutagenesis, since it provides information about a broad spectrum of mutation. Mutations in the hprt coding region were studied in 124 TG-resistant T-cell clones from 38 healthy, non-smoking male donors from a previously studied population of bus maintenance workers, fine-mechanics and laboratory personnel. Their mean age was 43 years (range 23-64) and their hprt mutant frequency was 9.3 +/- 5.2 x 10(-6) (mean +/- SD, range 1.4-22.6 x 10(-6)). Sequence analysis of hprt cDNA identified 115 unique mutations; 76% were simple base substitutions, 10% were +/-1 bp frameshifts, and 10% were small deletions within exons (3-52 bp). In addition, two tandem base substitutions and one complex mutation were observed. Simple base substitutions were observed at 55 (20%) of 281 sites known to be mutable in the hprt coding sequence. The distribution of these mutations was significantly different than would be expected based upon a Poisson distribution (P < 0.0001), suggesting the existence of 'hotspots'. All of the 87 simple base substitutions occurred at known mutable sites, but eight were substitutions of a kind that have not previously been reported at these sites. The most frequently mutated sites were cDNA positions 197 and 146, with six and five independent mutations respectively. Four mutations were observed at position 131, and three each at positions 143, 208, 508 and 617. Transitions (52%) were slightly more frequent than tranversions (48%), and mutations at GC base pairs (56%) more common than mutations at AT base pairs (44%). GC > AT was the most common type of base pair substitution (37%). The majority of the mutations at GC base pairs (78%) occurred at sites with G in the non-transcribed strand. All but one of eight mutations at CpG-sites were of the kind expected from deamination of methylated cytosine. Deletion of a single base pair (-1 frameshift) was three times more frequent than insertion of a single bp (+1 frameshift). Almost half (6/13) of the small (3-52 bp) deletions within the coding sequence clustered in the 5' end of exon 2. Short repeats and other sequence motifs that have been associated with replication error were found in the flanking regions of most of the frameshifts and small deletions. However, several differences in the local sequence context between +/-1 frameshift and deletion mutations were also noticed. The present results identify positions 197, 146 and possibly 131 as hotspots for base substitution mutations, and confirm previously reported hotspots at positions 197, 508 and 617. In addition, the earlier notion of a deletion hotspot in the 5'end of exon 2 was confirmed. The observations of these mutational cluster regions in different human populations suggest that they are due to endogeneous mechanisms of mutagenesis, or to ubiquitous environmental influences. The emerging background spectrum of somatic in vivo mutation in the human hprt gene provides a useful basis for comparisons with radiation or chemically induced mutational spectra, as well as with gene mutations in human tumors.

Clone Cells↗
PubMed1998

Locked nailing for displaced surgical neck fractures of the humerus.

OBJECTIVE: To report experience with a newly devised humeral locked nail for treating surgical neck fractures of the humerus. This device has the advantages of a small diameter for minimal tissue trauma and transfixing locking screws for reliable fixation. METHODS: From 1993 to 1996, 21 consecutive severely displaced surgical neck fractures of the humerus were antegrade nailed with humeral locked nails; 2 fractures were associated with dislocation and 1 fracture was a comminuted metaphyseal fracture with a failed plating. The average age of patients was 65.8 years; average follow-up time was 19.2 months. The proximal screws were applied upward in 5 patients and downward in 16 patients. Static locking was performed in 8 patients, dynamic locking in 13 others. RESULTS: The average operation time was 55 minutes. No patients needed blood transfusion. All fractures eventually achieved union with an average time to union of 14.8 weeks. On the basis of Neer criteria for outcome analysis, excellent or satisfactory results were obtained for 86% of the patients (18 of 21 patients). No patients had deep infection, implant failure, malunion, osteonecrosis, or nail migration that interfered with joint motion. Due to technique errors, one patient had shoulder joint impingement caused by protrusion of the proximal nail tip. CONCLUSION: The operative method reported here has the advantages of minimal tissue trauma, minimal hardware application, sufficient fixation, and easy operative technique, and it can be a worthy alternative for the treatment of severely displaced surgical neck fractures of the humerus.

Adult↗