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PubMed2006

Factors associated with future offending: comparing youth in grandparent-headed homes with those in parent-headed homes.

This study examined risk factors for reoffending by youth in grandparent-headed homes and those in parent-headed homes. Using data abstracted from the juvenile justice records of youth in a variety of living arrangements, we compared the records of 29 youth living in grandparent-headed homes with those of 37 youth living in parent-headed homes. Youth in grandparent-headed homes were significantly more likely to have risk factors and needs associated with reoffending. The findings suggest that youth in grandparent-headed homes are at greater risk for reoffending and that factors predisposing youth in grandparent-headed homes to reoffend may differ from those that predispose youth in non-grandparent-headed homes.

Adolescent↗
PubMed1992

Analysis of human red cell spectrin tetramer (head-to-head) assembly using complementary univalent peptides.

The mass-driven assembly of spectrin dimers to form tetramers involves two equal head-to-head alpha-beta associations and requires at least 30 degrees C for interconversion to occur readily. In this paper, the properties of tetramer formation were investigated using two complementary univalent peptides (the alpha I domain and beta monomers). Since the alpha I domain lacks an essential nucleation site required for side-to-side (lateral) heterodimer assembly [Speicher et al. (1992) J. Biol. Chem. 267, 14775-14782], these two peptides can only assemble head-to-head at a single site. This head-to-head assembly readily occurs at lower temperatures, indicating the temperature barrier for dimer-tetramer interconversion is caused by a conformational constraint of the dimer. This constraint, a closed hairpin loop, is released when the laterally associated partner is removed. The univalent alpha I-beta binding affinity at 37 degrees C (Ka = 1.4 x 10(5) M-1) is similar to the dimer-tetramer association constant at the same temperature. As the temperature is decreased from 37 to 0 degrees C, the alpha I-beta binding affinity increases about 32-fold. In contrast with head-to-head associations involving dimers, the second-order rate constants of two complementary univalent peptides (i.e., alpha I and beta) are dramatically higher, and the estimated activation energy (about 50 kJ mol-1) is about 5-fold lower. An open dimer conformation is an obligatory high-energy intermediate required for dimer-tetramer interconversion, and opening the dimer hairpin loop contributes about 190 kJ mol-1 to the activation energy for tetramer association.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, Gel↗
PubMedDate not supplied

Arthroscopic excision of the radial head: Clinical outcome in 12 patients with post-traumatic arthritis after fracture of the radial head or rheumatoid arthritis.

PURPOSE: We performed arthroscopic radial head excision in a series of patients with either post-traumatic arthritis after a radial head fracture or rheumatoid arthritis of the elbow as an expanded indication for elbow arthroscopy. The purpose of the study was to critically examine the results of arthroscopic chondroplasty of the radial head to determine the safety and effectiveness of the procedure. TYPE OF STUDY: Outcome study and retrospective analysis. METHODS: From 1990 to 1997, arthroscopic radial head resection was performed in 12 patients with either post-traumatic arthritis (n = 10, Mason type II or III) or with rheumatoid arthritis (n = 2). Functional outcome and radiographs were analyzed after a mean follow-up period of 39 months (range, 12 to 97 months). Elbow arthroscopy was performed using a standardized technique. The anterior three quarters of the radial head and 2 to 3 mm of the radial neck were resected with the abrader in the anterolateral portal and the arthroscope in the proximal medial portal. For resection of the posterior portion of the radial head, the abrader may be transferred to the mediolateral portal. This permits resection of the remnants of the radial head posteriorly and also at the proximal radioulnar joint. RESULTS: Preoperatively, patients lacked 23 degrees (range, 5 degrees to 40 degrees ) of extension of the elbow on average. Mean flexion was 111 degrees (range, 60 degrees to 145 degrees ). Patients had unrestricted pronation (limitation of 5 degrees in 2 patients). Two patients had a lack of supination of 15 degrees and 30 degrees. Mean follow up was 39 months (range, 12 to 97 months). Postoperatively, patients lacked 9 degrees (range, 0 degrees to 20 degrees ) of extension of the elbow on average. Mean flexion was 136 degrees (range, 90 degrees to 150 degrees ). No patient had subjective or objective evidence of instability of the elbow. All patients except one reported significant improvement in pain relief and complete relief of mechanical symptoms. CONCLUSIONS: This technically demanding surgical procedure should be reserved for situations of persistent, restricted range of motion and chronic pain. Arthroscopic radial head resection combined with arthroscopic synovectomy relieves elbow stiffness. The surgeon is able to deal with the intrinsic joint pathology, as well as with accompanying symptoms such as synovitis, capsular contracture, or loose bodies.

Adolescent↗
PubMed1998

Effects of calcium and bicarbonate on head-to-head agglutination in ejaculated boar spermatozoa.

The present study was conducted to reveal the effects of calcium and bicarbonate on the occurrence of head-to-head agglutination in ejaculated boar spermatozoa in vitro. Boar spermatozoa were washed and incubated in a modified Krebs-Ringer bicarbonate (mKRB) in a 37 degrees C CO2 incubator (5% CO2 in air) for 1-5 h. Before and after the incubation, aliquots of each sperm sample were fixed, smeared on glass slides, and stained with a phosphate-buffered solution of Giemsa to assess the percentages of head-to-head agglutinated spermatozoa. Before the incubation, only 5-12% of the spermatozoa were agglutinated. After the 1-h incubation, however, the percentage of head-to-head agglutinated spermatozoa rose to approximately 50%, followed by only minor increases thereafter. This rise was dependent on the concentrations of calcium chloride contained in the mKRB and was attenuated by the addition of 2 mM [ethylenebis(oxyethylenenitrilo)]tetra-acetic acid (EGTA) to the medium. Moreover, the replacement of sodium bicarbonate with 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (Hepes) in the medium and treatment with ruthenium red, which have both been shown previously to inhibit calcium uptake by boar spermatozoa, significantly reduced the rise. Based on these findings, it was concluded that extracellular calcium and bicarbonate are key factors regulating head-to-head agglutination in boar spermatozoa. The possible relationship between agglutinability and the fertilizing ability of boar spermatozoa is also discussed.

Animals↗
PubMed1971

The gramicidin A transmembrane channel: characteristics of head-to-head dimerized (L,D) helices.

A series of helical structures for gramicidin A, with alternating L and D residues, are characterized as to number of residues per turn, atoms in hydrogenbonded rings, and dihedral angles. Because of alternating peptide C-O directions, these helices are capable of forming head-to-head hydrogen-bonded dimers with the capacity of functioning as transmembrane channels. The dimers are characterized as to channel length, pore size, and expected ion selectivity. In a test of the proposed head-to-head association for channel formation, the malonyl dimer [N,N'-(dideformyl gramicidin A)-malonamide] was synthesized. The chemical and conformational integrity of the product was verified by nuclear magnetic resonance; in lipid bilayer studies, the dimer was found to be a potent mediator of ion conductance with the predicted concentration dependence.Thus, the results on malonyl gramicidin A prove head-to-head association in formation of the transmembrane channel, and the results are consistent with the specific geometrical configuration involved in head-to-head dimerization of pi((L,D)) helices. At this stage, the action of gramicidin A on membranes with lipid-layer thicknesses of 30 A or less can best be understood in terms of the pi((L,D)) helix with 6.3 residues per turn.

Amino Acid Sequence↗
PubMed2000

Phosphorylation of smooth muscle myosin heads regulates the head-induced movement of tropomyosin.

It has been shown that skeletal and smooth muscle myosin heads binding to actin results in the movement of smooth muscle tropomyosin, as revealed by a change in fluorescence resonance energy transfer between a fluorescence donor on tropomyosin and an acceptor on actin (Graceffa, P. (1999) Biochemistry 38, 11984-11992). In this work, tropomyosin movement was similarly monitored as a function of unphosphorylated and phosphorylated smooth muscle myosin double-headed fragment smHMM. In the absence of nucleotide and at low myosin head/actin ratios, only phosphorylated heads induced a change in energy transfer. In the presence of ADP, the effect of head phosphorylation was even more dramatic, in that at all levels of myosin head/actin, phosphorylation was necessary to affect energy transfer. It is proposed that the regulation of tropomyosin position on actin by phosphorylation of myosin heads plays a key role in the regulation of smooth muscle contraction. In contrast, actin-bound caldesmon was not moved by myosin heads at low head/actin ratios, as uncovered by fluorescence resonance energy transfer and disulfide cross-linking between caldesmon and actin. At higher head concentration caldesmon was dissociated from actin, consistent with the multiple binding model for the binding of caldesmon and myosin heads to actin (Chen, Y., and Chalovich, J. M. (1992) Biophys. J. 63, 1063-1070).

Animals↗
PubMed2005

Treatment of sequelae of radial head fractures with a bipolar radial head prosthesis: good outcome after 1-4 years follow-up in 11 patients.

BACKGROUND: In the presence of additional disruption of the distal radioulnar ligaments, the interosseous membrane, or the lateral- and/or medial collateral ligament, radial head fractures treated by resection will result in valgus elbow instability, proximal radial migration and/or posterolateral rotatory instability. Radial head replacement has been used to treat or prevent this. We report our experience with the Judet CRF II radial head prosthesis. PATIENTS AND METHODS: We treated 11 patients with a bipolar radial head prosthesis because of elbow instability after previous treatment for Mason-Johnston type III or IV radial head fractures. The outcome was assessed clinically using two standardized elbow function assessment scales, and radiographically after a mean follow-up of 2 years. RESULTS: Clinical outcome was either good or excellent in all patients; all elbows were stable. Radiographically, there were no signs of loosening, fracture or heterotopic ossification. 2 patients required reoperation for subluxation of the prosthesis; both were treated by reducing the size of the modular head of the prosthesis. There was erosion of the capitellum in 1 patient. INTERPRETATION: Bipolar radial head replacement can be used successfully for treatment of the sequelae of radial head fractures. The long-term outcome is, however, unknown.

Adult↗
PubMed1997

Hormonal responses and cardiac filling pressures in head-up or head-down position and pneumoperitoneum in patients undergoing operative laparoscopy.

In order to determine if there are differences in stress responses, as reflected in neuroendocrine activation, we have compared data from two groups of patients undergoing laparoscopic surgery either in the head-up position for cholecystectomy or in the head-down position for hysterectomy. Arterial blood samples were obtained for measurement of serum concentrations of cortisol, catecholamines, renin activity and atrial natriuretic peptide (measured as N-terminal peptide of proANP), and haemodynamic data (pulmonary capillary wedge pressure, PCWP) were collected at the following times: in awake patients, supine at rest (baseline); in awake patients in the position used during surgery; during laparoscopy; and 2 h after surgery. The same anaesthetic technique and normocapnic mechanical ventilation were used in both groups. There were no significant differences between groups in cortisol or adrenaline concentrations, or in renin activity. There was, however, a three-fold increase in cortisol towards the recovery period in both groups. Noradrenaline concentrations increased more in the head-up group suggesting increased sympathetic nervous activity. In awake patients, plasma NT-proANP concentrations were significantly higher in the head-down tilt compared with the head-up position, and NT-proANP correlated well with PCWP. During pneumoperitoneum, however, NT-proANP concentrations remained low in spite of increased PCWP suggesting that inflation of the abdomen interferes with venous return. In conclusion, abdominal surgical laparoscopy in both the head-up and head-down positions caused marked activation of neuroendocrine responses. The two surgical positions, however, differed in their effect on the circulation. In awake patients, head-down tilt was associated with increased concentrations of plasma NT-proANP, indicating increased venous return and atrial stretch.

Adult↗
PubMed1990

Effect of head activator on proliferation, head-specific determination and differentiation of epithelial cells in hydra.

In hydra the differentiation of head-specific ectodermal epithelial cells from multipotent stem cells is a multistep process in which cell cycle progression is regulated at three restriction points. Head activator acts as a positive signal at these restriction points. At the G2/mitosis boundary of epithelial stem cells head activator functions as a mitogen, being necessary for cell division. Subsequently, in or before S phase, head activator acts as determinant to ensure commitment of epithelial cells to head-specific determination. This effect of head activator requires hundredfold-higher concentrations, and may also require longer incubation times, than for cell proliferation. Epithelial cells thus committed to head-specific differentiation become arrested in G2 as a third and last restriction point in the cell cycle. They require disinhibition by decapitation and probably the presence of head activator for final differentiation, which then occurs in G2.

Animals↗
PubMed1972

Bacteriophage T4 head morphogenesis. IV. Comparison of gene 16-, 17-, and 49-defective head structures.

Defective heads present in extracts of bacteriophage T4 gene 16, 17, or 49 mutant-infected cells have been characterized. All appeared as empty shells when examined by negative-stain electron microscopy and showed essentially the same polypeptide pattern on sodium dodecyl sulfate-acrylamide gels. However, when analyzed by several other methods, gene 16- and 17-defective heads were shown to differ markedly from phage heads present in gene 49-defective extracts. First, the gene 16- and 17-defective structures were found to possess a large number of attached tails (50%, rather than about 5%). Second, they contained less nuclease-resistant deoxyribonucleic acid (DNA) (3 versus 18% of a phage equivalent), had a smaller sedimentation coefficient (240 versus 315S), and a lighter density (1.31 vs. 1.34 g/ml) than gene 49-defective heads. Third, they were not attached to the intracellular DNA pool through a deoxyribonuclease-sensitive linkage. Finally, 8-nm diameter capsomers were clearly revealed on the surface of many gene 16- and 17-defective structures. There was a total of 305 +/- 25 capsomers per particle, which yielded an approximate molecular weight of 84 x 10(6) for these heads. The capsomers were presumably not seen on gene 49-defective heads because of the large amount (18%) of associated DNA. These results support the contention that gene 16- and 17-defective heads, in contrast to gene 49-defective structures, represent abortive rather than intermediate structures in T4 head morphogenesis.

Carbon Isotopes↗
PubMed1977

Bacteriophage T4D head morphogenesis. VIII. DNA-protein associations in intermediate head structures that accumulate in gene 49--mutant-infected cells.

We have utilized the gene 49(-) mutant-infected cells of bacteriophage T4D to accumulate large numbers of nucleic acid-protein intermediate head structures. These heads were used as substrates for experiments in the investigations of the mechanism of DNA packaging. Specifically, we have examined: (i) the susceptibility of the DNA in these structures to digestion by a variety of nucleases after a series of increasing temperature pulses from 25 to 100 degrees C, (ii) the physicochemical characteristics of the DNA inside these heads, and (iii) the mechanism by which proteins are displaced from the interior of the head after treatment with basic proteins. We isolated DNA from these gene 49(-) heads by use of gradient centrifugation procedures. The DNA had a molecular weight of 8 x 10(6) and a density of 1.697 +/- 0.005 g/cm(3), and it contained a short resistant fraction (SRF) which, when associated with the gene 49(-) heads, exhibited AT-protected regions that were not susceptible to micrococcal nuclease digestion. Such a fraction may contain pieces which are important in the initial association of the DNA with the prohead. Exposure of the gene 49(-) intermediate capsid structures to basic proteins, such as bovine trypsin inhibitor, lysozyme, and l-polylysine-70, caused a displacement of an amorphous-appearing structure which may be a complex of the gene 49(-) DNA and interior components of the capsid (e.g., internal proteins, polyamines). Our general conclusion is that in the gene 49(-) intermediate head structures which are only partly filled with DNA, this DNA is held inside the head by strong electrostatic linkages with interior polypeptides and polyamines.

Capsid↗
PubMed2003

Laxity of the elbow after experimental excision of the radial head and division of the medial collateral ligament. Efficacy of ligament repair and radial head prosthetic replacement: a cadaver study.

We studied the stabilising effect of prosthetic replacement of the radial head and repair of the medial collateral ligament (MCL) after excision of the radial head and section of the MCL in five cadaver elbows. Division of the MCL increased valgus angulation (mean 3.9 +/- 1.5 degrees) and internal rotatory laxity (mean 5.3 +/- 2.0 degrees). Subsequent excision of the radial head allowed additional valgus (mean 11.1 +/- 7.3 degrees) and internal rotatory laxity (mean 5.7 +/- 3.9 degrees). Isolated replacement of the radial head reduced valgus laxity to the level before excision of the head, while internal rotatory laxity was still greater (2.8 +/- 2.1 degrees). Isolated repair of the MCL corrected internal rotatory laxity, but a slight increase in valgus laxity remained (mean 0.7 +/- 0.6 degrees). Combined replacement of the head and repair of the MCL restored stability completely. We conclude that the radial head is a constraint secondary to the MCL for both valgus displacement and internal rotation. Isolated repair of the ligament is superior to isolated prosthetic replacement and may be sufficient to restore valgus and internal rotatory stability after excision of the radial head in MCL-deficient elbows.

Aged↗
PubMed2001

Arthroplasty with a metal radial head for unreconstructible fractures of the radial head.

BACKGROUND: Treatment of unreconstructible comminuted fractures of the radial head remains controversial. There is limited information on the outcome of management of these injuries with arthroplasty with a metal radial head implant. METHODS: The functional outcomes of arthroplasties with a metal radial head implant for the treatment of twenty-five displaced, unreconstructible fractures of the radial head in twenty-four consecutive patients (mean age, fifty-four years) were evaluated at a mean of thirty-nine months (minimum, two years). There were ten Mason type-III and fifteen Mason-Johnston type-IV injuries. Two of these injuries were isolated, and twenty-three were associated with other elbow fractures and/or ligamentous injuries. RESULTS: At the time of follow-up, Short Form-36 (SF-36) summary scores suggested that overall health-related quality of life was within the normal range (physical component = 47 +/- 10, and mental component = 49 +/- 13). Other outcome scales indicated mild disability of the upper extremity (Disabilities of the Arm, Shoulder and Hand score = 17 +/- 19), wrist (Patient-Rated Wrist Evaluation score = 17 +/- 21 and Wrist Outcome Score = 60 +/- 10), and elbow (Mayo Elbow Performance Index = 80 +/- 16). According to the Mayo Elbow Performance Index, three results were graded as poor; five, as fair; and seventeen, as good or excellent. The poor and fair outcomes were associated with concomitant injury in two patients, a history of a psychiatric disorder in three, comorbidity in two, a Workers' Compensation claim in two, and litigation in one. Subjective patient satisfaction averaged 9.2 on a scale of 1 to 10. Elbow flexion of the injured extremity averaged 140 degrees +/- 9 degrees; extension, -8 degrees +/- 7 degrees; pronation, 78 degrees +/- 9 degrees; and supination, 68 degrees +/- 10 degrees. A significant loss of elbow flexion and extension and of forearm supination occurred in the affected extremity, which also had significantly less strength of isometric forearm pronation (17%) and supination (18%) as well as significantly less grip strength (p < 0.05). Asymptomatic bone lucencies surrounded the stem of the implant in seventeen of the twenty-five elbows. Valgus stability was restored, and proximal radial migration did not occur. Complications, all of which resolved, included one complex regional pain syndrome, one ulnar neuropathy, one posterior interosseous nerve palsy, one episode of elbow stiffness, and one wound infection. CONCLUSIONS: Patients treated with a metal radial head implant for a severely comminuted radial head fracture will have mild-to-moderate impairment of the physical capability of the elbow and wrist. At the time of short-term follow-up, arthroplasty with a metal radial head implant was found to have been a safe and effective treatment option for patients with an unreconstructible radial head fracture; however, long-term follow-up is still needed.

Adolescent↗
PubMed2006

Comminuted radial head fractures treated with a modular metallic radial head arthroplasty. Study of outcomes.

BACKGROUND: Comminuted fractures of the radial head are challenging to treat with open reduction and internal fixation. Radial head arthroplasty is an alternative treatment with results that compare favorably with those reported after open reduction and internal fixation of similar fractures. The purpose of this study was to evaluate the two-year outcomes and the rate of recovery of a closely followed cohort of patients in whom an unreconstructible radial head fracture had been treated with a modular metallic prosthesis. METHODS: Twenty-six patients (seventeen female and nine male; mean age, fifty-four years) with an unreconstructible comminuted radial head fracture and associated elbow injuries were treated with a modular metallic radial head arthroplasty. Patients who had presented more than four weeks following the injury or had had the radial head arthroplasty as a second-stage or salvage procedure were excluded. Of the twenty-six patients, twenty-two had an associated elbow dislocation, and thirteen of them also had an associated fracture of the coronoid process. Patients were prospectively followed at three, six, twelve, and twenty-four months. Self-reported limb function, general health, range of motion, and isometric strength were assessed by an independent observer. RESULTS: Following treatment of the injury, significant decreases in self-reported and measured impairments were noted over time, with the majority of the recovery occurring by six months and little further recovery noted between six and twenty-four months. There were slight-to-moderate deficits in the range of motion and strength compared with the values on the contralateral, unaffected side. Patient satisfaction was high at three months and remained high at two years. All elbow joints remained stable, no implant required revision, and there was no evidence of overstuffing of the joint. Mild osteoarthritis was seen in five (19%) of the twenty-six patients. CONCLUSIONS: An arthroplasty with a modular metallic radial head is a safe and effective option for the treatment of unreconstructible radial head fractures associated with other elbow injuries. Recovery primarily occurs by six months, with minimal additional improvements over the next eighteen months.

Adult↗
PubMed1995

Wear of the polyethylene acetabular cup. The effect of head material, head diameter, and cup thickness studied with a hip simulator.

Ultra-high molecular weight polyethylene acetabular cups backed by Ti-6Al-4V acetabular shells were articulated against Co-Cr-Mo alloy, ion-implanted Co-Cr-Mo alloy, and zirconia ceramic femoral heads in a hip joint simulator. Three tests of three million walking cycles each were run with five different head-cup combinations. The wear of the cups was measured gravimetrically at half a million cycle intervals. When the thickness of the cup was 10.9 mm, the mean wear rate was 0.14 mm/year against 28 mm dia. Co-Cr-Mo heads and 0.09 mm/year against ion-implanted 28 mm Co-Cr-Mo heads. When the thickness of the cup was 7.0 mm, the mean wear rate was 0.04 mm/year against 28 mm zirconia heads, but when the thickness was 10.9 mm, no wear occurred against 28 and 32 mm zirconia heads. The results indicate that a significant reduction in the wear of the polyethylene cup can be expected if zirconia is used as the head material, instead of Co-Cr-Mo alloy or ion-implanted Co-Cr-Mo alloy. The diameter of the zirconia head, 28 vs. 32 mm, seems unimportant, but a cup thickness much below 10 mm may be disadvantageous.

Acetabulum↗
PubMed1990

[Comparative study on head nurses' perception to own role and staff nurses' role expectation to their head nurse between university hospitals and general hospitals].

The organization of nursing department significantly effects the hospital management. Especially, the head nurse is one of the most important position because head nurse is a first-line manager in the hospital level, a middle manager in nursing service organizations level and the top manager in each nursing unit level. This study was attempted to show the ideal model and rule by compare head nurses' role perception with staff nurses' role expectation according to two types of hospital. The survey was conducted among 94 head nurses and 233 staff nurses who are working at 5 different University Hospitals over 600 beds and 93 head nurses and 218 staff nurses who are working at 12 different General Hospitals between 100-300 beds in Seoul. The data was collected in a period from 8th September to 13th October in 1989 and the instrument used for this study was based on Han's one and referred back to many literary sources and revised. The collected data was analysed by computer using S.P.S.S. program as a Mean, Percentage, Cronbach's alpha, Chi-Square, t-test and ANOVA. 1. The study was compared to the difference of the two subject group's general characteristics according to a type of hospital. As a result, there were significant differences in age, educational background and career. 2. This Study was compared to the difference of the two subject group's role perception and role expectation about each question according to a type of hospital. The result of this comparisons as follows: First, These were the most important issue between both groups: "Head nurse has to know about her staff's events and problems and then help them to solve that promptly" Second, These were the least important issue between both groups: "Head nurse has an interview with patient's family and visitors", "Head nurse is interested in her staff's privacy". 3. This study was compared to the differences of each role areas according to a type of hospital. As a result, there were no significant differences both two subject groups except nursing manager role in staff nurses' group (t = -2.893, df = 449.0, p = 0.004). 4. This study was tested to the difference of the two subject groups according to general characteristics. As a result, All of that there were no significant differences.

Hospitals, General↗
PubMed2003

Electronic off-peak status of one head of a dual-head gamma camera resulted in bone scintigraphy artifacts and faulty findings on gated myocardial SPECT.

OBJECTIVE: Gamma cameras contain energy discriminators that allow only those photons within a specified energy range to be recorded. A spontaneous shift in peak of 1 head of a dual-head gamma camera may cause artifacts. We present our experience with the incidental occurrence of off-peak status in 1 head of a dual-head gamma camera that resulted in subsequent artifacts and poor-quality images. METHODS: Four patients had been scheduled to undergo imaging on a newly installed dual-head gamma camera on the same morning. The first patient underwent (201)Tl-chloride anterior and posterior total-body imaging to check for metastatic thyroid cancer, and the images were of adequate quality for interpretation. The next 2 patients underwent dual-isotope rest (201)Tl-chloride and gated dipyridamole (99m)Tc-tetrofosmin myocardial SPECT. The rest (201)Tl myocardial SPECT images of both patients showed normal perfusion in the left ventricular wall, but the dipyridamole (99m)Tc SPECT images showed virtual absence of perfusion in the apical, anterior, and lateral walls. These findings might suggest myocardial ischemia. In addition, 1 of 2 patients' cardiac gated SPECT findings led to inaccurate left ventricular ejection fractions. Technologists did not become aware of the artifacts until the fourth patient underwent total-body bone scanning, which showed faint activity with loss of contrast in the entire anterior body. One of the camera heads was then found to have off-peak status. Thus, we abandoned use of 1 detector of the dual-head gamma camera and repeated the anterior bone scanning of the 4th patient and the dipyridamole SPECT of 1 of the 2 cardiac patients. RESULTS: Gated cardiac SPECT abnormalities resulting from off-peak status were difficult to identify and included abnor-mal left ventricular wall perfusion and an inaccurate left ventricular ejection fraction. It was determined later that the off-peak status was caused by malfunction of a photomultiplier tube. CONCLUSION: Degraded planar images resulting from the off-peak status of a camera head are easily identified. The presence of the same pattern of abnormalities in 2 consecutive myocardial SPECT examinations should alert technologists to the possibility that the abnormalities are, in fact, artifacts.

Artifacts↗
PubMed1998

Dizziness from whiplash and head injury: differences between whiplash and head injury.

OBJECTIVE: Large discrepancies exist in the literature regarding incidence and types of symptomatology in whiplash. This is because of the evolution of whiplash injury over the years with the advent of head rests and seat belts. Previous authors have regarded symptoms of dizziness as a result of brainstem or cerebellar injury or both. It has been difficult in those studies to ascribe a mechanism of injury, as patients with whiplash injury only have been grouped with those who have incurred mild traumatic brain injury as a result of a significant blow to the head. The authors saw the need to delineate patients who had suffered whiplash injury from those who also had suffered mild head injury, as defined in the rehabilitation-neurosurgical literature, to attempt to define differences in symptoms, abnormalities, and mechanisms of recovery in these two groups. STUDY DESIGN: The study design was a retrospective case review. SETTING: The study was conducted at a tertiary-quaternary referral clinic. PATIENTS: The records of 36 patients were reviewed. Nineteen of these patients suffered a whiplash-associated disorder and 17 suffered a mild head injury as well. These patients were referred for assessment of symptoms persisting for at least 2 years after their injury. Patients were excluded if they had not completed clinical assessment, including electronystagmography (ENG) and computerized dynamic posturography (CDP). INTERVENTIONS: A full history, otolaryngologic examination, including assessment of eye movements, corneal reflexes and gait, as well as an investigation, including ENG and CDP, and history taking and detailed recording of related complaints immediately before diagnostic work-up were performed. MAIN OUTCOME MEASURES: Symptoms reported by patients who had received either whiplash alone or whiplash plus mild head trauma as defined in the literature were measured. Patients were classified according to type of accident, type of injury suffered, and degree and nature of posturographic abnormalities. RESULTS: Patients often have similar complaints regardless of whether or not they had suffered a head injury. Although CDP showed abnormalities in both groups, standard ENG assessment, including caloric testing, showed abnormalities only in the head-injured group. The posturographic abnormalities also were analyzed in both groups, and it was found that there was a correlation between the type of posturographic abnormality and the type of injury suffered. Although ENG testing is done routinely, posturography is shown to be more sensitive in picking up abnormalities. In addition, the authors have shown that posturography can delineate the type of injury suffered by exhibiting the compensation strategy used as well as the efficacy of that compensation strategy. CONCLUSIONS: Because ENG abnormalities are limited to patients who have suffered a head injury, the inference is that these two groups of patients have suffered damage at different sites along the balance system pathways, but both of these lesions can lead to similar symptoms. Although the mechanisms of whiplash injury and how they affect the vestibular system are poorly understood, posturography testing is essential in inferring how a patient is recovering by measuring how and how well the patient is overcoming his or her deficit. This has important medical legal implications regarding legitimizing a patient's problem, prognostic factors, as well as rehabilitation plans, measures, and outcomes.

Adolescent↗