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There have been anecdotal reports that hairs that regrow after ruby laser-assisted hair removal are finer in appearance. If true, this phenomenon adds to the improved aesthetic effect of laser treatment of unwanted hair. It is the aim of this study to determine whether this phenomenon indeed occurs, and if so, assess its permanence and its mode of action. In this prospective clinical study, 71 patients with 94 treatment sites were treated with the Chromos 694 Depilation Ruby Laser. Hair diameter was measured pre-treatment, and at 3 and 7 months post-treatment. In addition, ex vivo scalp skin was used to assess if the ruby laser selectively damaged coarser hairs. Laser-treated and matched untreated skin samples were histologically assessed and the diameters of hair shafts (normal or obviously damaged) were measured. Results of this study were analysed using Kruskal-Wallis one-way analysis. There was no statistically significant difference between the hair diameter of non-lasered specimens and the hair diameter of the normal hair in lasered specimens. However, a statistically significant difference was seen between the hair diameter of non-lasered specimens and diameters of damaged hair in lasered specimens (P < 0.05). There was a statistically significant difference (P < 0.05) between pre-treatment and 3 month hair diameters, but no statistically significant difference was found between pre-treatment and 7 month hair diameters. In conclusion, ruby laser-assisted hair removal results in a temporary reduction in hair diameter of regrowing hair. This is not due to the selective targeting of larger hair follicles.

Small bowel perforation caused by sharp or pointed foreign bodies rarely is diagnosed preoperatively because clinical symptoms usually are nonspecific and can mimic other surgical conditions such as appendicitis and cecal diverticulitis. We report the case of a 57-year-old man who underwent diagnostic laparoscopy for abdominal pain of unknown etiology. Swelling and erythema were noted in a segment of small bowel in the right lower abdomen. A tiny sharp-pointed object was found penetrating the inflamed portion of the bowel. This foreign body was removed and the perforation immediately repaired under laparoscopic guidance. The postoperative course was uneventful. We believe that in cases of lower abdominal pain with peritoneal irritation, laparoscopy can provide not only a wide field of examination to localize intraabdominal pathology, but in some instances it can aid in case management.

Despite widespread demand for efficient, reliable methods of eliminating unwanted hair from the face and body, available options were limited until the recent development of laser-assisted hair removal systems. This is a review of the various types of hair removal methods available today with an emphasis on laser-assisted hair removal.

The ruby laser is effective in removing unwanted body hair. The occurrence of cutaneous side-effects such as blistering, hypopigmentation and hyperpigmentation, however, remains problematic. These side-effects are more commonly seen in patients with dark coloured skin, which partly explains the relative scarcity of information on the efficacy of ruby laser hair removal in such patients. The mechanisms of the occurrence of these side-effects are also not known. It was the aim of this study to evaluate the efficacy of ruby laser-assisted hair removal in patients with Fitzpatrick skin type V in a retrospective clinical study and to evaluate the mechanism of post-treatment pigmentary change in a prospective clinical study. The percentage reduction in hair density in patients with skin type V was assessed after a variable period following treatment with the Chromos 694 Depilation Ruby Laser, and was compared with the results of those with skin types I-IV. To study the pigmentary change and melanocyte numbers after laser irradiation, ex-vivo scalp skin and serial patient biopsies were taken and stained with S-100, dopa oxidase and Masson-Fontana methods. Laser treatment reduced melanocyte numbers as measured by DOPA stain but not by S100. Laser treatment resulted in the clearance of pigment from the epidermis on histology. Ruby laser was shown to be effective in removing unwanted hair from patients with dark coloured skin, but with a higher incidence of cutaneous side-effects. The occurrence of hypopigmentation after laser irradiation was thought to be due to the suppression of melanogenesis in the epidermis rather than to destruction of the melanocytes.

Ruby laser-assisted hair removal is thought to work via selective photothermolysis, which relies on light reaching the deeper layers of skin, and the absorption of light by the target chromophore, melanin. It is therefore possible that efficacy of treatment is affected by anatomic factors that determine the amount of light reaching the hair bulbs (i.e., skin color, depth of intracutaneous hair, epidermal thickness and dermal density) and the melanin content of hair. To examine this hypothesis, a prospective study was performed. Forty-eight volunteers were treated with the Chromos 694 Depilation Ruby Laser at a single standard fluence of 11 J/cm2. Treatment efficacy was determined by measuring hair density at 3 and 7 months after treatment. Epidermal depth and dermal density were measured from 2-mm biopsies taken before treatment, and the intracutaneous hair length was determined from plucked hair. Skin color was assessed using a spectrophotometer, and melanin content of dissolved hair was assessed using spectrophotometry. Efficacy of treatment for each patient was compared with the patient's age, intracutaneous hair length, epidermal depth, dermal density, skin color, and total melanin content and relative eumelanin content of hair. No correlation was found between the efficacy of treatment and age and the various anatomic factors. Patients with higher eumelanin content in their hair had better long-term results (Spearman rank test, p = 0.00219). The results suggested that the efficacy of treatment did not depend solely on the amount of laser light penetrating the skin but correlated well with the eumelanin content of hair. The clinical implication of this finding is discussed.

A ruby laser has been developed to remove unwanted hair. Melanin within the hair is used as a natural chromophore. It is postulated that photothermal damage destroys the hair itself and also key cells surrounding the hair follicle to prevent regrowth. A prospective study of laser depilation in 116 patients or 175 sites was performed over a period of 18 months. All the patients had tried other methods of hair removal and found them to be unsatisfactory. Hair counts (follicles/cm2) were used to judge the outcome. The mean follow-up time was 23.25 weeks (range 12-76 weeks). After a mean number of treatments of 1.92 (range 1-20) there was a 56.4% reduction in hair density. Comparing pre- and post-treatment hair density, there was a highly significant reduction (paired t-test: P < 0.00001). Laser removal of hair is now a realistic treatment option.

Background: Although visual field defects are well-known complications of optic disc drusen, reduction in visual acuity with this condition is rare., Method/results: We report on a 68-year-old male with bilateral optic disc drusen who presented with monocular loss of vision in the right eye associated with an inferior altitudinal visual field defect and signs consistent with acute anterior ischaemic optic neuropathy, confirmed on fluorescein angiography. He also had a left inferior nasal step, but no evidence of glaucomatous cupping. The disc drusen were documented clinically and on B scan ultrasound and computed tomography., Conclusions: The diagnosis of acute anterior ischaemic optic neuropathy should be considered in patients with optic disc drusen who present with reduced visual acuity, particularly when the visual loss has been acute and non-progressive and is associated with altitudinal field loss and characteristic fluorescein angiography signs.

Several clinical studies on the efficacy of ruby laser-assisted hair removal have reported that regrowth of hair after treatment is common. One of the reasons for the regrowth of hair is the incomplete destruction of germinative hair cells due to the insufficient penetration of the ruby laser in the skin. It was the aim of this study to estimate the extent of damage to the hair follicles after one ruby laser treatment and to determine whether the ruby laser destroyed the bulbs and the bulge regions of hair follicles. The extent of laser damage in hair shafts was determined by serial examination of six specimens of ex vivo scalp skin lasered with the Chromos 694 Depilation Ruby Laser at 14 J per square centimeter and 20 J per square centimeter. Another nine specimens of ex vivo scalp skin were similarly lasered, and monoclonal antibody LP2K was used to identify the bulge regions of the hair follicles using the immunoperoxidase technique. Damage to the bulge region was assessed from consecutive specimens, which were stained with hematoxylin-eosin stain. The mean depth of laser damage sustained by hair follicles was 1.34 mm (14 J per square centimeter) and 1.49 mm (20 J per square centimeter) underneath the skin surface. Most of the laser damage involved the bulge regions but fell short of the hair bulbs. The laser damage did not seem to extend far enough down the hair shafts to result in permanent hair destruction. The clinical implications of this finding are discussed.

An unpredictable response, even in patients with dark hair, often undermines successful ruby laser hair removal. A prospective clinical study was carried out to evaluate the roles of melanin content and growth phases of hair in treatment efficacy. Thirty-six volunteers with white skin and dark hair were recruited for the study, and were all treated using the Chromos 694 Depilation Ruby Laser. The overall efficacy of treatment was assessed at the end of 3 months. The efficacy of laser treatment is not due solely to the proportion of hair in the growing or static phase of the hair cycle. There is a lack of correlation between the melanin content and the overall efficacy of laser hair removal in those treated once, but patients with darker hair responded better after repeated treatments. The proportion of hair in the growth phase and the melanin content of hair do not contribute solely to the efficacy of ruby laser hair removal.

We hypothesize that excyclorotation of the globe and extraocular muscle cone associated with external orbital rotation around each orbital axis in craniofacial conditions could be at least partially corrected by leaving the anterior periorbita (periosteum lining the orbit) attached to the surgically rotated portion of the orbit. This hypothesis was tested by comparing the degree of rotation of the globe in response to internal rotation of the anterior orbit, leaving the periorbita attached to the rotated portion of the orbit on one (study) side, and stripping the periorbita on the opposite (control) side, in nine fresh cadavers. There was a highly significant difference (P < 0.0001) between the study and control sides. The possible extrapolations of this finding to the clinical situation are discussed.

This article examines cervical deformities and their treatments, such as iatrogenic deformities, posttraumatic deformities, ankylosing spondylitis, rheumatoid arthritis, degenerative subaxial spondylolisthesis, myopathy, infectious spondylitis, and tumors. Congenital scoliosis and kyphosis and torticollis and rotatory atlanto-axial subluxation also are discussed.

The rationale of anterior versus posterior, or combined fusion is discussed with regards to different clinical diagnoses and situations. Factors involved in the decision-making process include stability, magnitude of deformity, rigidity of deformity, neurologic considerations, bone quality, and medical/metabolic factors. Careful preoperative assessment and planning are required as well as consideration for the patient's overall well being.

Purpose: To investigate antigenic and morphologic features of microglial and vascular elements in the neural retina associated with age-related macular degeneration (ARMD) compared with those features in age-matched normal and young adult retinas., Methods: Adult eyes (n = 97) were classified histopathologically into normal and ARMD-associated groups. Peroxidase imunohistochemical examination of retinal flatmounts was used to visualize major histocompatibility complex class II (MHC-II) immunoreactivity; the intensity and distribution of labeling were quantified by image analysis. In histochemical investigation, reduced nicotinamide-adenine dinucleotide phosphate diaphorase and glial fibrillary acidic protein or MHC-II double labeling were used to detect vascular changes in some preparations., Results: An increase in the proportion of the retina (percentage of total area) expressing MHC-II immunoreactivity was observed in age-matched retinas compared with that seen in normal retinas. A significant increase (P < 0.05) in the percentage of area immunoreactive for MHC-II was observed, primarily on vascular elements, in retinas with incipient ARMD compared with the area affected in the age-matched group. Increased MHC-II immunoreactivity on vessels in the normal-aged group observed with confocal microscopy was associated with irregularities in the organization of astrocytes. Hypertrophy of retinal microglia was also apparent, although the intensity of microglial MHC-II immunoreactivity was not significantly different between groups., Conclusions: The results indicate that an increase in MHC-II immunoreactivity on retinal vascular elements is associated with normal aging. A further increase in MHC-II immunoreactivity on vascular elements and morphologic changes in microglia was associated with incipient ARMD. Immunologic responses in neural retinal microglia and vascular elements appear to be related to early pathogenetic changes in retinal pigment epithelium pigmentation and drusen formation.

The majority of splenic cysts occur as a result of parasitic infection, most commonly in countries where hydatid disease is endemic. In the Western world however, their occurrence is extremely rare and aetiology less clear. Approximately 800 cases of non-parasitic splenic cysts have been reported in the world literature to date. Their presentation ranges from that of an incidental finding on abdominal examination to catastrophic intraperitoneal haemorrhage. The methods of treatment of splenic cysts are protean with no universally accepted policy. We report a case of a massive splenic cyst in an adolescent female treated by partial splenectomy. We also present a review of the pertinent literature on this subject paying special attention to the role of conservative surgery with preservation of normal splenic tissue.

The Australian National Liver Transplantation Unit carried out 251 multiple organ-retrieval procedures between January 1986 and December 1994: 53% were in the Sydney metropolitan area, 22% in country New South Wales and the Australian Capital Territory, 21% interstate and 4% in New Zealand; mean total procurement times were, respectively, 4 hours 57 minutes, 6 hours 58 minutes, 9 hours 20 minutes and 12 hours 20 minutes. Donor operation times steadily decreased over the nine years. One-year patient and graft survival rates were 77.1% and 70.3%, respectively; primary non-function occurred in only one case. The importance of coordination of donor organ procurement and efficient organ retrieval to the success of transplantation programs is discussed.

The free TRAM flap is now commonly used in breast reconstruction after mastectomy. A number of our patients reported anecdotally return of some sensation in their reconstructed breasts, despite being told beforehand that this was unlikely. This study measured return of sensation in a series of 21 patients, by studying both patients' subjective reporting of sensory return using a standardised questionnaire and objective evaluation of sensation with standard clinical tests. These included temperature and pain threshold and the use of the Semmes-Weinstein method. The study demonstrates that measurable sensory recovery occurred in 16 of our 21 patients (76%). 18 of the 21 patients (86%) reported a subjective feeling of sensation in the reconstructed breast and 7 (33%) claimed it felt the same as their normal contralateral breast. Sensory recovery usually commences about 6 months postoperatively and progressively improves over time. These findings demonstrate that the free tissue transfer method does not necessarily lead to an insensate reconstruction, as might be supposed.

An unusual case of stress fracture of the first rib that occurred in a young male as a result of the constant loading due to carrying a heavy schoolbag is reported. This case demonstrates the difficulty in diagnosis and highlights the need for awareness of this condition, thus avoiding invasive investigation.

The innovations in laparoscopic technology have expanded the variety of general surgical procedures amenable to laparoscopic approach. An initial experience with eight cases of laparoscopic splenectomy is presented. The indications for splenectomy were immune thrombocytopenic purpura (ITP, n = 6), hereditary spherocytosis (n = 1) and enlarged spleen with filling defects (n = 1). There were six females and two males, aged 27 to 46 years. Seven patients had the spleen removed laparoscopically and one had laparoscopically assisted splenectomy. The operations took from 2 h 15 min to 3 h 30 min (mean 2 h 45 min). The spleens removed varied from 70 to 563 g (mean = 250). Blood loss ranged from insignificant to 1400 mL. Significant bleeding was encountered in three patients with moderate splenomegaly (240, 350, 563 g). Two patients received autologous blood transfusion. The average narcotic required was three doses. The patients were discharged after a mean postoperative stay of 3 days (range 2-4). One patient developed a below knee deep venous thrombosis. Laparoscopic splenectomy is possible and promises to provide the advantages associated with other laparoscopic procedures. Patients with an enlarged spleen can present a technical challenge, and there is a potential for significant blood loss. The current technology and laparoscopic expertise means that this procedure should probably be limited to patients whose spleens are not palpable clinically.

Glove perforation during surgery represents a potential risk of infection for the surgeon. The authors postulated that thicker latex gloves may offer greater protection. The perforation rates for the Ansell Gammex glove and the thicker Baxter Triflex gloves were compared in single- and double-glove usage and no difference was found between the two brands, in either usage. The authors recommend double-gloving for all orthopaedic operations with regular glove changes during major procedures.

Purpose: The role of arterial stenting in the treatment of femoral and popliteal arterial disease is controversial and has been hampered by recommendations for patients to be given anticoagulants (oral warfarin) for several months or more. This study was undertaken to evaluate the immediate and midterm outcomes of vascular stents implanted percutaneously in the femoral and popliteal arteries, without long-term anticoagulation., Methods: Over a 3-year period, 32 patients admitted to a vascular surgery service had arterial stents implanted in the femoral (n = 22) or popliteal (n = 10) artery for the following indications: recurrent stenosis after angioplasty (n = 13), suboptimal result after angioplasty of occluded (n = 12) or calcified stenotic arteries (n = 2), percutaneous transluminal angioplasty-induced thrombosis or dissection (n = 5). Access to the artery was gained by percutaneous insertion of a hemostatic sheath into the ipsilateral common femoral artery. Systemic heparin was given at the time of stent insertion, and patients were prescribed daily low-dose aspirin., Results: Successful stent implantation was achieved in 31 of the 32 patients. Acute thrombosis (< 30 days) occurred in two patients. There was no incidence of false aneurysm formation, acute leg ischemia, or vessel perforation. All patients were monitored by Doppler scanning index and duplex scanning within 24 hours, and thereafter at 3- to 6-month intervals. The mean ankle-brachial systolic pressure index improved from 0.60 (before treatment) to 0.88 (3 to 6 months after stenting). Stent occlusion has occurred in six patients; two stents were successfully salvaged with urokinase infusion. In follow-up to date (range 3 to 33 months) the primary patency rate by life-table analysis was 75% at 18 months, whereas the secondary patency rate was 89% at the same interval. Restenosis (> 50% lumen diameter) was detected by duplex ultrasonography in seven of 25 patent stents (28%) at a mean interval of 9.5 months (range 4 to 15 months); of these, four patients remained clinically symptom-free despite the ultrasound findings., Conclusions: We conclude that vascular stents can be implanted into the femoropopliteal arteries with few complications and with acceptable early and intermediate patency rates, without the need for long-term anticoagulation. Restenosis is not prevented by stents, and the main value of stenting at this site appears to be in salvaging acute complications of percutaneous transluminal angioplasty, or to correct suboptimal results after recanalization of occluded arteries.

Mesenteric cyst is one of the rarest abdominal tumours, with approximately 820 cases reported since 1507. The incidence varies from 1 per 100,000 to 250,000 admissions. The lack of characteristic clinical features and radiological signs may present great diagnostic difficulties. The cyst may present in one of three ways: (i) non-specific abdominal features; (ii) an incidental finding; or (iii) an acute abdomen. Abdominal pain is the major presenting symptom. Abdominal mass is found in more than 50% of cases and 40% of cases are discovered incidentally. More than one aetiological mechanism is probably involved in the development of mesenteric cysts. Mesenteric cysts have been reported from the duodenum to the rectal mesentery but are most commonly located in the ileal mesentery. Malignant cysts occur in less than 3% of cases. Enucleation of the cyst is the treatment of choice. Knowledge of these tumours is important due to the various complications associated with suboptimal surgical management. Two cases of mesenteric cysts are presented including a recurrent mesenteric cyst in a post-partum woman demonstrating the inferior technique of internal marsupialization. The association of mesenteric cyst with pregnancy is discussed.

One hundred and thirty-seven children with Campylobacter diarrhoea were reviewed. The predominant species was C. jejuni. Ninety-five percent of the children were below 5 years of age with 61% of these being 2-12 months old. A slight male preponderance was noted. About half the cases presented with fever and bloody diarrhoea; vomiting was seen in 28% and abdominal colic in only 8%. Moderate to severe diarrhoea was present in 48% of the children. Thirty-seven percent had a history of recent or concurrent illness. Other bacterial enteropathogens together with Campylobacter were isolated in 15% of the children. Erythromycin, the most useful drug, when indicated for Campylobacter infections, had an MIC90 of 2 mg/l with 96.2% of the strains being sensitive.

Day-only admissions for surgery are strongly encouraged, in an effort to keep costs down. Varicose vein surgery has been considered too major for day-only management despite the fact that there have been studies from overseas showing that it can be done with a morbidity comparable to inpatient surgery. The morbidity of day-only surgery for varicose veins (both long and short saphenous procedures) was assessed and compared with the results of inpatient surgery. Patients were also asked whether they were satisfied with the surgery being done this way. There were 165 consecutive patients available for study, 64 day-only and 101 inpatient. All patients attending Shellharbour Hospital. Shellharbour, had surgery done as day-only (as it was a morning list and allowed adequate time for recovery). Patients attending Bulli Hospital, Bulli, had surgery done as an inpatient (afternoon list). All surgery was performed by one surgeon. There was no difference (Chi-squared) in the age distribution (mean 48 years for day-only, 51 years for inpatient) or sex proportion in either group (Chi-squared test of proportions with continuity correction). Assessment of the results was done by review of the surgeon's notes, as well as telephone interviews for day-only subjects. The complication rate in both groups was similar. Wound problems represented the main complication with an incidence of 10.5% in each group. There was one deep venous thrombosis (DVT) in each group (diagnosed by duplex scan). Response to the telephone interview suggested that most patients were happy to have the surgery done as a day-only procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

This study describes the expression of MHC class II antigens in retinal flat mounts from normal donors and patients with Alzheimer's disease (AD). We confirm previous observations of MHC class II immunoreactivity on microglia in normal retinae, while observing insignificant levels of reactivity on endothelial cells (EC). A significantly increased level of MHC class II expression was detected in AD retinae. This increased immunoreactivity was found to occur in the absence of lymphocytic infiltrates, suggesting that the pathogenesis of AD in the retina may be distinct from that reported to occur in some regions of the brain. MHC class II expression, measured using computerized optical densitometry, appeared to be increased principally as a result of induced MHC class II immunoreactivity on EC. Ramified microglia and perivascular macrophages, although hypertrophied, appeared to show unchanged levels of MHC class II expression. These findings are consistent with earlier suggestions that both aberrant MHC class II expression and suppressor activity of resident macrophages may restrict immune responses.

The effects of photon noise in the emission projection data and uncertainty in the attenuation map on the image noise in attenuation-corrected SPECT images reconstructed using a maximum-likelihood expectation-maximization algorithm were investigated. Emission projection data of a physical Hoffman brain phantom and a thorax-like phantom were acquired from a prototype emission-transmission computed tomography (ETCT) scanner being developed at UCSF. Computer-simulated emission projection data from a head-like phantom and a thorax-like phantom were also obtained using a fan-beam geometry consistent with the ETCT system. The simulation assumed a 99Tcm source, included collimator blurring but ignored photon scatter. For each phantom, a region of interest (ROI) at the centre of the reconstructed image was chosen for the purpose of noise analysis. In all cases, the mean value (m) in the ROI approached a constant value after approximately 20 iterations. The standard deviation (sigma) generally increased with the number of iterations. The ratio (sigma/m) was found to be inversely proportional to the square root of the total detected counts and proportional to the relative uncertainty in the attenuation maps. These two noise components contributed independently towards the noise in the reconstructed image. In the ETCT system employing an x-ray tube for attenuation map acquisition, the uncertainty in the reconstructed radionuclide distribution is limited mainly by photon noise in the emission projection data. Our results are expected to be generally applicable to other emission-transmission systems, including those using external radionuclide sources for the acquisition of attenuation maps.

We have previously reported an observation that the regulatory sequence of the human papillomavirus (HPV) type 18 genome elicits only basal and unregulated transcriptional activities in transgenic mice [Choo et al., Virology (1992) 188:378-383]. We have now extended the study to other transgenic mice carrying an entire or a subgenomic fragment of HPV-16 and -18. Extremely low levels of HPV transcripts were detected in various organs of the mice only by reverse transcriptase-based polymerase chain reaction. On analysis of the methylation status of the HPV transgenome sequences, hypermethylation was clearly observed, therefore suggesting a possible explanation for low level HPV transgenome transcriptional activity in HPV transgenic mice.

The cosmetic result, cost effectiveness, and complication rate of three different types of skin closure: staples, tapes, and interrupted nylon were compared. In 68 wounds, skin closure was randomized to staples, tapes, or interrupted 3/0 nylon sutures. All wounds were closed subcutaneously with interrupted undyed 2/0 dexon. For 3 months, 59 wounds were followed and assessed by an independent observer at 1 and 3 months postoperatively in the outpatient department. In three different skin closures, the cosmetic result was superior for tapes because the wound line itself was finer and there were no dot scars. Tapes were the most cost-effective because they are the cheapest although they were not as quick to apply as staples. There was no difference in complication rate. Tapes also afforded the greatest patient comfort.

We have developed a prototype imaging system that can perform simultaneous x-ray transmission CT and SPECT phantom studies. This system employs a 23-element high-purity-germanium detector array. The detector array is coupled to a collimator with septa angled toward the focal spot of an x-ray tube. During image acquisition, the x-ray fan beam and the detector array move synchronously along an arc pivoted at the x-ray source. Multiple projections are obtained by rotating the object, which is mounted at the center of rotation of the system. The detector array and electronics can count up to 10(6) cps/element with sufficient energy-resolution to discriminate between x-rays at 100-120 kVp and gamma rays from 99mTc. We have used this device to acquire x-ray CT and SPECT images of a three-dimensional Hoffman brain phantom. The emission and transmission images may be superimposed in order to localize the emission image on the transmission map.

A simple method for obtaining a collimated near-unity aspect ratio output beam from laser sources with extremely large (> 100:1) aspect ratios is demonstrated by using a distributed-feedback grating-surfaceemitting laser. Far-field power-in-the-bucket measurements of the laser indicate good beam quality with a high Strehl ratio.

We present a case of extensive recurrence of a retro-pharyngeal liposarcoma following surgical removal 18 years previously. The surgery and pathology are discussed, and management strategies of head and neck liposarcomas are reviewed.

A prototype Emission-Transmission Computed Tomography (ETCT) system is being developed that will acquire single-slice x-ray transmission CT images simultaneously with single photon emission computed tomography (SPECT) images. This system will permit the correlation of anatomical information from x-ray CT with functional information from SPECT images. The patient-specific attenuation map derived from the x-ray CT images can be used to perform attenuation correction of the SPECT images, so that accurate quantitative information can be obtained. The fan-beam scanning geometry and the use of a segmented HPGe detector array impose special constraints on the design of the collimator for the system. Based on a signal detection model, an efficiency-resolution figure of merit (ERFM) as a function of the collimator geometric efficiency, system resolution width, and object diameter is defined. The ERFM is proportional to the square of the detection signal-to-noise ratio. The collimator design parameters can then be optimized by optimizing the ERFM for an anticipated object diameter. The collimator point-spread function, geometric efficiency, and resolution are calculated. The collimator optimized for the detection of a 1-cm object will have a single-slice point source efficiency of 1.2 X 10(-4), and a FWHM of 6.5 mm at the center of the reconstruction circle, at 12 cm from the collimator face. The minimum object contrast which will give a detection SNR of 5 is 74%, for a total accumulated count per slice of 2 X 10(6).

Four cases of node-based T cell lymphoma are presented. The tumours had 2 distinct morphologic patterns. Two cases showed a polymorphous proliferation of pleomorphic lymphoid cells, small lymphocytes, epithelioid cells and arborizing small vessels while the others displayed a monomorphous infiltrate of large atypical lymphoid cells characterized by granular nuclei with numerous tortuous folds to produce a 'squiggly' appearance. One case showed a progression from one histological pattern to the other. Confirmation of the T cell nature of these lymphomas was based on the demonstration of E-rosette formation by morphologically atypical lymphoid cells which also stained positive for acid alpha-naphthyl acetate esterase activity. The patients had an average age of 52 yr and presented with a variable distribution of lymphadenopathy and a predominance of extranodal involvement. Two cases disclosed hypergammaglobulinaemia, one of whom had a paraproteinaemia of IgM-k type. All patients responded poorly to standard combination chemotherapy, 2 expiring 48 and 53 mth after onset of symptoms.

The clinical course of pneumothorax and its allied conditions was studied in 34 newborn infants who presented over a 2 1/2-year period. We found an overall incidence of 3/1000 live births. 11 term infants without obvious pulmonary pathology presented early (9 within minutes of birth); 6 of these had aspirated meconium or blood. The remaining 23 were preterm infants with hyaline membrane disease (HMD) and accounted for 68% of the infants in this series. In contrast, they presented late (mean 45 hours) and 16 were on continuous distending pressure (CDP) or intermittent positive pressure ventilation (IPPV) at the onset of pneumothorax. 15% of all infants with HMD who required CDP/IPPV developed pneumothorax; this increased incidence was most evident in infants who received CDP only. All except 2 of the 11 term infants in the first group were managed conservatively and all survived. Wehn pneumothorax occurred as a complication of HMD in preterm infants, 14 of the 16 infants required intrapleural drainage. Persistence or recurrence of pneumothorax occurred in 9 infants, 7 of whom were receiving CDP/IPPV at the time. Lung expansion was affected only after replacement with a patent chest drain through the same incision or insertion of a second drain on the same side of the chest. All 5 deaths occurred in the group of preterm infants with HMD. 3 resulted directly form respiratory failure due to severe HMD complicated by pneumothorax. We emphasize the increasing importance of pneumothorax as a complication of HMD in preterm infants, particularly in those receiving CDP. Successful management depends on prompt diagnosis and treatment of pneumothorax, which may occur as unexplained sudden deterioration at any time during the course of illness in this group of high risk infants.

Artificial heart valves fashioned from bovine pericardial tissues appear to perform favourably when compared to those fashioned from other biological materials. Tissue mechanical properties have been implicated as a possible factor in determining the success or failure of the materials used for constructing tissue valve substitutes. In this study, strips of bovine pericardial tissues, cut in three different directions (along the base-apex axis of the heart, perpendicular to this axis and at an angle of 45 degrees to this axis), were subjected to uniaxial tensile tests using an Instron machine, at strain rates of 666.7, 166.7, 66.7, and 6.7% X min-1. The pericardial tissues were found to have non-linear stress-strain curves. Anisotropy was also observed, in that the tissue was most extensible when stretched along the vertical direction and least extensible when stained along the horizontal direction. The tissues also exhibited viscoelastic properties, as the extensibility was found to decrease with the increasing strain-rate. The strain at rupture for these tissues, however, were found to be independent of the strain rates and the direction in which they were stretched. On the other hand the stress at rupture was largest when stretched in the horizontal direction and least when stretched in the vertical direction. Stresses at rupture also increase with the strain rate. The implications of the observed tissue properties, when these are used in the fashioning of tissue valve substitutes, will be discussed.

Three cases of the localized form of congenital generalized fibromatosis are described in females under one year. The lesions were in the parotid region, biceps muscle and abdominal wall. The infiltrative or nodular pattern of these tumours with the periphery resembling smooth muscle and the central portion resembling a haemangiopericytoma makes them a distinct histological entity. Ultrastructurally, these tumours are composed of myofibroblasts. The differential diagnosis from other soft tissue tumours in infancy and early childhood is discussed. These tumours are benign and recurrence after complete local excision is rare.

Only three cases of tracheal paraganglioma have been reported in the literature. This paper describes an additional case, which showed pharmacological and ultrastructural evidence of hormone secretion. It is suggested that this tumor is derived from true paraganglia located in the trachea and not from misplaced or aberrant paraganglionic tissue. Hemoptysis was the only presenting symptom in two of the four reported cases and significant bleeding occurred during biopsy in the other two cases. The long-term prognosis appears good if complete resection is possible.