Radiation dosimetry of technetium-99m-DMSA in children

Radiation dosimetry was performed on 24 children (aged 5 wk to 14.8 yr) who were undergoing routine diagnostic investigation of renal impairment with 99mTc-DMSA.

METHODS

Organ doses were calculated using MIRDOSE 3 with biokinetic data obtained in previously described studies, and effective doses and effective dose equivalents were estimated. Interpolation by inverse weight between pediatric anthropomorphic phantoms was compared with age-matching to discrete phantoms. Administered activities were scaled by body surface area from the adult activity of 100 MBq and the resulting radiation doses in normal children were compared with those that would have resulted from a schedule based on body weight.

RESULTS

The effective doses estimated by interpolation differed by up to 46% from those based on discrete phantoms and showed less variation. In children with normal bilateral renal function, the mean effective dose per administered activity was 0.91 +/- 0.08 mSv or 0.98 +/- 0.29 mSv by the two methods, respectively. Renal pathology reduced the effective dose, on average, by 15% of the value for normal patients.

CONCLUSION

Over the pediatric age range, the uniformity of effective dose values was improved by scaling the administered activity according to body surface area rather than to body weight.

Selective liver enzyme induction by carbamazepine and phenytoin in Chinese epileptics

OBJECTIVE

Anticonvulsant drugs are known inducers of cytochrome P450 liver enzymes and it has been suggested that this induction increases susceptibility to paracetamol-induced hepatotoxicity.

METHODS

We measured the percentage urinary recovery of paracetamol and its metabolites after a dose of 20 mg kg-1, and the excretion of 6 beta-hydroxycortisol as a ratio to urinary free cortisol (6 beta OHF/F) in Chinese epileptic patients maintained on long-term therapy with carbamazepine (n = 6) or phenytoin (n = 6).

RESULTS

Compared to the healthy controls (n = 20), patients on phenytoin had significantly lower recoveries of mercapturic acid, cysteine and sulphate metabolites, but a higher recovery of glucuronide metabolites of paracetamol. The recoveries of paracetamol metabolites in patients on carbamazepine were not different from controls. In contrast, the 6 beta OHF/F was significantly higher in patients on carbamazepine (3-fold) or phenytoin (2-fold) compared to controls. Healthy control Chinese subjects metabolised paracetamol in a similar way to that reported in Caucasians, indicating that the risk for hepatotoxicity would be the same. Our findings in a group of Chinese patients on phenytoin were also similar to those previously reported in Caucasians on this drug. The apparent differences in the pattern of isoenzyme induction between the groups on phenytoin and carbamazepine require verification in larger studies. The data do not suggest an increased risk of paracetamol-induced hepatotoxicity in Chinese patients on anticonvulsants.

Cervical spine in Pfeiffer's syndrome

Studies of cervical spine anomalies in patients with Crouzon's and Apert's syndromes have shown an increased incidence of fusions in comparison with that in the normal population. Currently, only small series of patients with Pfeiffer's syndrome who exhibit abnormalities have been published. The objective was to assess the incidence and pattern of radiological cervical spine abnormalities in patients with Pfeiffer's syndrome. All cervical spine radiographs of 22 patients with a confirmed diagnosis of Pfeiffer's syndrome treated at Great Ormond Street Hospital during the last 10 years were studied. All of the radiographs were reviewed by the craniofacial team along with a pediatric radiologist with experience in the assessment of skeletal dysplasias. Radiological abnormalities included hypoplasia of the neural arches, hemivertebrae, and a "butterfly" vertebra as well as vertebral fusion. Evidence of vertebral fusion was present in 16 (73%) of cases. Fusion of both the vertebral bodies and the posterior elements were noted. C2-C3 was the level most commonly involved, although fusion was noted at all levels within the cervical spine. Block fusions involving multiple vertebrae were noted. Analysis of sequential radiographs in 11 patients revealed evidence of progression in eight patients. These results reveal an incidence of anomalies that is higher than previously reported. The older age of the patients in our study demonstrates the progressive nature of the cervical fusions in Pfeiffer's syndrome.

Acute effects of the potent lacrimator o-chlorobenzylidene malononitrile (CS) tear gas

1. The use of tear gas to control civil unrest is accepted practice by government authorities worldwide. It is rarely used in Hong Kong but during a recent riot at a Vietnamese detention centre large quantities were used and this was cause for some concern. 2. All patients presenting to the British Red Cross Clinic after the incident were seen by one of the authors. To establish if exposure to tear gas had serious effects on the health of the detainees, the case records of the 184 patients with symptoms consistent with CS exposure were reviewed 2 months later. 3. The most common complaints were burns (52%), cough (38%), headache (29%), shortness of breath (21%), chest pain (19%), sore throat (15%) and fever (13%). However, the only common findings on examination by a physician were burns (52%) and an inflamed throat (27%). All burns could be categorised as "minor' according to the American Burns Association classification and all were consistent with CS gas exposure. 4. Some patients complained of other symptoms that had not been previously reported in the literature, such as haemoptysis (8%) and haematemesis (4%), but these were only confirmed in one patient. 5. The majority of patients had recovered within 2 weeks of exposure although one asthmatic patient complained of shortness of breath lasting for 33 days and a sore throat lasting for 38 days after the incident. She had abnormally low peak expiratory flow readings, but had a clinical history of asthma. 6. No serious sequelae were encountered, but the incidence of burns in these patients was higher than would be expected from a review of the literature. However, very little data on the effects of tear gas in a riot situation has been published. There have been reports of high concentrations of CS gas causing reactive airways dysfunction but this was not seen in our group of patients.

The short insulin tolerance test: feasibility study using venous sampling

The short insulin tolerance test (ITT) is both a simple and valid method of quantifying insulin sensitivity although arterialization of samples and the risk of hypoglycaemia remain as potential difficulties. We examined the safety and reproducibility of using venous sampling with insulin doses of 0.1 U kg-1 and 0.05 U kg-1 in healthy subjects. Whole blood glucose concentrations were measured contemporaneously and the rate of plasma glucose decline (mmol l-1 min-1) for each test was estimated from unlogged venous plasma glucose concentrations measured at 1 min intervals. The mean rates of plasma glucose decline for the 0.1 U kg-1 and 0.05 U kg-1 insulin doses were 0.26 mmol l-1 min-1 (n = 11, range = 0.17-0.41, intrasubject coefficient of variation (CV) = 9.4%) and 0.25 mmol l-1 min-1 (n = 6, range 0.19-0.46, intrasubject CV = 15.9%), respectively. Reversal of significant hypoglycaemia was necessary in one subject before 15 min post-insulin. We found that: (1) venous sampling provides a reproducible measure of glucose uptake after insulin, (2) contemporaneous bedside glucose sampling identifies those at risk of significant hypoglycaemia during the ITT, and (3) the 0.1 U kg-1 dose response is more reproducible and no less safe than the half dose response. We conclude that the current ITT protocol would be made safer and simpler with the above modifications although further studies comparing venous with arterialized sampling are needed.

A comparison of the pharmacokinetics and pharmacodynamics of cilazapril between Chinese and Caucasian healthy, normotensive volunteers

METHODS

The pharmacokinetics and pharmacodynamics of the angiotensin converting enzyme (ACE) inhibitor cilazapril were studied in 12 Chinese and 13 Caucasian, healthy, normotensive volunteers on their normal diet. Cilazapril was given orally as a single 2.5 mg capsule. Plasma was sampled for assay of the active metabolite, cilazaprilat, plasma renin activity (PRA), aldosterone, angiotensin I (AI) and ACE-activity. Plasma concentrations of the active drug were measured by radioimmunoassay. Blood pressure and heart rate were measured at regular intervals.

RESULTS

The pharmacokinetic parameters of cilazaprilat were similar in the two ethnic groups. No significant difference in plasma concentrations was found at any of the time points. However, the weight-adjusted plasma clearance was significantly higher in the Chinese group, which is compatible with their lower body weight. The effects on plasma hormones were also comparable, although there was a somewhat greater rise in PRA and greater fall in aldosterone levels in Chinese than in Caucasians. The effect of cilazapril on blood pressure and heart rate was greater than was previously reported in healthy volunteers. Systolic (SBP) and diastolic (DBP) blood pressure were significantly reduced in both groups, but there was a more prolonged reduction in DBP in Caucasians. In addition, heart rate (HR) was significantly increased from baseline from 5 h onwards in Chinese subjects and significantly higher in comparison with Caucasians at most time points from 1.5 h onwards. The pharmacokinetic parameters of cilazapril were essentially the same in healthy, normotensive Chinese and Caucasians. Cilazapril reduced blood pressure acutely in both groups, with good tolerance. The inhibition of ACE in relationship to time and the plasma concentrations of cilazaprilat were similar in the two groups, although the changes in PRA and aldosterone suggest an ethnic difference in the responses of the renin-angiotensin-aldosterone system.

Systemic responses to SFHS-infusion in hemorrhaged dogs

Anesthetized mongrel (weight range: 16-27 Kg) dogs were prepared for monitoring hemodynamics, blood flow distribution, plasma colloid osmotic pressure and renal functional parameters at various intervals. Removal of 35 ml/Kg blood resulted in marked drop and only partial spontaneous recovery in systemic and pulmonary arterial pressures, cardiac output and organ blood flows (> 50% flow-decrements occurred in kidney, spleen, heart, gut and pancreas); plasma colloid osmotic pressure as well as urine output and creatinine clearance also fell. Group I (n = 6) of dogs was transfused after 45 minutes of hypovolemia with their own anticoagulated blood, while Group II (n = 6) received an equal volume of unmodified 6% stromafree hemoglobin solution (SFHS). Comparison of the two groups' responses to resuscitation yielded some differences. There was a significant overshoot (30 mmHg) in systemic arterial blood pressure accompanied by bradycardia in Group II only. Cardiac output recovered in both groups but was less well sustained in Group II. Cerebral blood flow rose higher and hepatic arterial flow-increment was less in Group II than in Group I; the responses to resuscitation in the other organs were comparable. Colloid osmotic pressure decreased in Group I whereas it rose immediately after resuscitation in Group II, declining thereafter with a converging trend and 30 minutes thereafter the differences were not significant between the groups. Urine excretion and creatinine clearance recovered to comparable extents in both groups, but N-acetyl-beta-D-glucosaminidase (N.A.G.) excretion rose over 10-fold higher in Group II than in Group I. These experiments have defined the response of bled animals to resuscitation with unmodified, unpurified SFHS, when compared to resuscitation with whole blood, showing a less well sustained but adequate hemodynamic and renal functional recovery while revealing indications of early renal tubular cellular injury, providing baseline comparison for testing highly purified and modified hemoglobin solutions.

Mutation of serine 90 to glutamic acid mimics phosphorylation of bovine prolactin

Phosphorylated prolactin has been identified and isolated from bovine pituitaries. The biological activity of this phosphoprotein is severely reduced in comparison with nonphosphorylated prolactin. The sites of phosphorylation are serines 26, 34, and 90, and the stoichiometry is 1:1:10, respectively. In this report, the phosphoserine residues have been individually replaced with glutamic acid in recombinant methionyl bovine prolactins in order to mimic phosphorylation at each site. Substitution of glutamic acid for serine at positions 26, 34, and 90 reduced protein helical contents by 10, 6, and 14%, respectively. UV absorbances for S26E and S34E bovine prolactins were blue-shifted, similar to the biological isolates of phosphorylated bovine prolactin, but the biological activities of the S26E and S34E mutants (ED50 values of 16.3 and 18.8 pM, respectively) were similar to that of wild-type prolactin (ED50 value of 18.6 pM) in the Nb2 rat lymphoma assay. S90E bovine prolactin had the greatest reduction in helical content but showed similar UV and fluorescent spectra to the wild-type bovine prolactin. The biological activity of S90E bovine prolactin (ED50 value of 672 pM) was reduced to an activity similar to that of phosphorylated bovine prolactin. The data indicate that the phosphorylation of serine 90 is responsible for the reduction in biological activity.

Children with intractable focal epilepsy: ictal and interictal 99TcM HMPAO single photon emission computed tomography

Fourteen children with intractable complex partial seizures underwent ictal and interictal 99TcM HMPAO single photon emission computed tomography (SPECT) scans. Abnormalities concordant with clinical and/or EEG localisation were present in 13 of 14 ictal and/or interictal scans. Focal hyperperfusion was seen at the seizure focus on ictal scans and focal hypoperfusion was seen on interictal scans. The timing of the injection in relation to the start of the seizure was crucial for reliable localisation. While recognisable patterns of regional cerebral blood flow (rCBF) were seen on either interictal or ictal scans, marked changes in the patterns of rCBF between the ictal study and interictal study provided the most reliable information about seizure localisation. Using both ictal and interictal studies, 99TcM HMPAO SPECT may provide data about both the seizure origin and its relationship to structurally abnormal regions of the brain.

Extrarenal Wilms' tumour presenting with intraperitoneal haemorrhage

Extrarenal Wilms' tumours are very rare and have usually been reported as isolated cases. Presentation occurs with a painless abdominal mass. This case report is the first presentation of such a tumour with intraperitoneal haemorrhage. The investigation and surgical management are discussed and the need for urgent surgical assessment reinforced.

Cutaneous neuroendocrine (Merkel cell) carcinoma. A report of 35 cases

Cutaneous neuroendocrine (Merkel cell) cancer (CNEC) is a rare skin tumor with a highly malignant nature. Initial treatment of this tumor has often been limited to a local excision. The medical records of 35 patients diagnosed with CNEC and treated at Southern California Kaiser Permanente Medical Group or UCLA Medical Center between 1980 and 1991 were reviewed. There were 26 male and 9 female patients were enrolled in this study. Minimum follow-up from date of diagnosis was 18 months, mean follow-up was 40 months; 25 patients presented with local disease (stage I) and 10 patients presented with regional disease (involved nodes, stage II). Patients who were treated initially with local therapy alone had a 65% recurrence rate and a 29% mortality rate, while those patients treated locoregionally at presentation had only a 27% recurrence rate and 14% mortality rate, although the majority presented with more advanced disease. Due to the high incidence of lymph node failure and death in patients treated locally versus locoregionally at presentation, we feel that planned locoregional treatment is indicated for all patients presenting with CNEC, regardless of stage.

Orbital floor fractures in young children

Isolated orbital floor fractures in children before the end of the 7th year of life are said to seldom occur. This is thought to be due to differences in anatomy from adults in that the maxillary sinus is developing and the orbit is still increasing in size. Two cases of isolated orbital floor fractures in children aged less than 8 years are reported, their management discussed, and the literature reviewed.

Comparison of the pharmacokinetics and pharmacodynamics of oral doses of perindopril in normotensive Chinese and Caucasian volunteers

1. The pharmacokinetics of perindopril and perindoprilat and the hormonal and haemodynamic responses following a single oral dose were studied in 12 Chinese and 10 Caucasian healthy, normotensive volunteers on two occasions. Perindopril was given on the first occasion as a 4 mg dose and then after at least 10 days as a weight-adjusted dose of 4 mg/70 kg. Plasma was sampled for assay of perindopril, perindoprilat, plasma renin activity (PRA), aldosterone, angiotensin I (AI) and ACE activity. Urine was collected for perindopril and perindoprilat assay. A radioimmunoassay technique was used to measure the prodrug and its active metabolite. 2. The time to maximum concentration (tmax) for perindopril was shorter for the Chinese group after the 4 mg dose (median 0.5, range 0.5-1.5 h vs median 1.0, 0.5-1.5 h P < 0.05) and also tended to be shorter after the weight-adjusted dose (median 0.5, range 0.5-1.0 h vs median 1.0, range 0.5-3.0 h). Cmax and AUC tended to be higher after the 4 mg dose in the Chinese group who had a lower body weight than the Caucasians. 3. The tmax of perindoprilat tended to be shorter for both doses and there was a tendency towards a higher Cmax after the 4 mg dose in the Chinese group but there was no statistically significant difference between the two groups. 4. There were no differences in the levels of PRA, plasma AI, plasma aldosterone or the degree of ACE-inhibition for either dose in the two ethnic groups. 5. Blood pressure was measured at intervals up to 24 h post-dose in both the supine and standing positions. Perindopril reduced blood pressure acutely with respect to the pre-dose level with good tolerability in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxyradical generation after resuscitation of hemorrhagic shock with blood or stroma-free hemoglobin solution

Hypovolemic states are characterized by inadequate tissue perfusion; when this state is reversed, the reintroduction of oxygen is accompanied by the excess generation of oxyradicals and these, in turn, may cause "reperfusion injury" in susceptible tissues. When hemoglobin solution is used to resuscitate the hypovolemic state, the generation of oxyradicals may be enhanced by catalytic means. The generation of oxyradicals was estimated in dogs subjected to the acute removal of 35 ml/Kg blood, and resuscitated 45 mins thereafter with an equal volume of either autologous blood (Group I, n = 6) or 6% stromafree hemoglobin solution (S.F.H.S.) (Group II, n = 6). Hepatic and pancreatic enzymes were measured in blood drawn at intervals. The hypovolemic state was characterized by profound hypotension which was reversed by resuscitation. Oxyradical generation in arterial blood samples, drawn at various times, was estimated by the generation of oxidation products (2,3- and 2,5-dihydroxybenzoic acid) of exogenously administered sodium salicylate, determined by HPLC in plasma samples extracted with diethyl ether. Salicylate oxidation products rose significantly above the baseline value in Group I dogs, whereas they rose 5-6-fold higher than the baseline values in those of Group II. The actual values attained and the increments were significantly (p < .05) greater in Group II than in Group I. In the group resuscitated with S.F.H.S., catalytically active iron concentration in plasma also rose 10-12-fold higher and was associated with spuriously elevated levels of gamma-glutamyl transferase due to interference with the assay. These findings are consistent with the hypothesis that blood-resuscitation of hypovolemic shock is accompanied by oxyradical generation of a modest degree; in contrast, S.F.H.S.-resuscitation introduces catalytically active iron and is accompanied by oxyradical generation of a significantly greater degree.

Fractures of the facial skeleton in children

Fractures of the facial skeleton in children are uncommon. This study presents the results of 139 children who sustained a total of 161 such fractures and were admitted to the Royal Hospital for Sick Children, Edinburgh, between January 1983 and December 1992. The male to female ratio was 3:1 and the highest incidence was at age 10 years. Analysis of fracture patterns showed that despite differences in anatomy, the fracture patterns were similar to those occurring in adults, but the relative proportion of each fracture type was different in children. Nasal fractures occurred most frequently (54 per cent), mandibular fractures constituted 30 per cent, and middle third fractures only 16 per cent. Falls, sporting injuries and road traffic accidents (RTA) were the major causes of these injuries. Injuries sustained in RTA were most likely to have involved cyclists or pedestrians in contrast to earlier series which have identified these injuries mainly among car passengers. No deaths were recorded and most patients made a complete recovery, although a few required secondary surgery for complications. This taken in conjunction with the findings of both high numbers of associated injuries, and increased severity commonly occurring in both mandibular and middle third injuries leads to the suggestion that these should be treated in centres where multidisciplinary management can easily be coordinated.

Skin cancer prevention: a link between primary prevention and early detection?

The aim of this paper was to determine if there is any link between primary prevention and early detection for skin cancer. Results from a study of a large random sample of Gold Coast residents (N = 995) identified an association (P < 0.01) between individual primary prevention and early detection activities. People were also more likely to use both prevention methods if they had personal experience with skin cancer (P = 0.01) or if they were male (P = 0.05). Future primary prevention and early detection skin cancer programs might be most effective if they are combined.

Effect of renal maturation on the clearance of technetium-99m mercaptoacetyltriglycine

To investigate the effect of growth and maturation on the global kidney clearance of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3), we investigated 509 children who attended for 99mTc-MAG3 renography in our department. In order to estimate the normal maturation of the kidney, only children who were classified as "normal" using diagnostic criteria were included in this study (n = 109). Kidney clearance was calculated using a gamma camera technique and a 20-min blood sample. There was a progressive increase in the clearance of 99mTc-MAG3 throughout childhood and into adolescence (mean clearance value below 2 month was 31.4 ml/min, mean clearance value above 12 years was 287 ml/min). When clearance was normalised to body surface area (BSA) a different pattern was seen, with a progressive increase from 3 weeks of age (mean value < 0.2 years: 208 ml/min/1.73 m2) to a plateau at the end of the first year of life (mean value > 2 years: 303 ml/min/1.73 m2). Maturation of the kidney as defined by the normalised clearance of 99mTc-MAG3 is therefore complete by the end of the 1st year of life, after which any change in non-corrected clearance values may be attributed to growth. To investigate the appropriate normalisation factor for 99mTc-MAG3 clearance in children, clearance values were compared to height, weight and BSA. The relationships were described using a linear model; the correlation coefficients demonstrated that BSA has the highest strength of relationship with 99mTc-MAG3 clearance. Body surface area may be used over 1 year of age to normalise the clearance values of 99mTc-MAG3.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of small airway dysfunction in asymptomatic smokers using aerosol bolus behavior

Tests using inhaled particles assess ventilatory nonuniformities and may be sensitive to early changes in the small airways of cigarette smokers. We measured aerosol bolus behavior in 20 asymptomatic smokers and 20 age- and sex-matched nonsmokers for comparison with pulmonary function parameters including the single-breath nitrogen test. Narrow boluses containing 1-micron particles were introduced into 1-I breaths and inhaled to varying lung depths. We examined changes in bolus shape between inhalation and exhalation using plots of aerosol concentration versus respired volume for measurement of bolus dispersion, volumetric change in mean location (mean shift), and quantitative particle deposition. We found exhaled bolus dispersion to be significantly increased in smokers compared with nonsmokers. Volumetric mean shift was significantly different in smokers at shallow lung depths, with the center of bolus mass occurring later in exhalation. FEV1/FVC in smokers was significantly inversely correlated with dispersion at deeper lung depths and with mean shift at all lung depths. Smokers with abnormal spirometry (n = 4) or an abnormal single-breath nitrogen test (n = 7) had significantly increased dispersion compared with smokers with normal pulmonary function tests. We conclude that aerosol bolus dispersion is a useful tool for examination of small airway function in asymptomatic smokers.

Cancer of the anal canal: treatment with chemotherapy and low-dose radiation therapy

PURPOSE

To determine the efficacy of a standardized protocol of chemotherapy and low-dose radiation therapy in treatment of patients with anal canal cancer.

MATERIALS AND METHODS

Forty-two consecutive patients with anal canal cancer were treated with 15 fractions of 30-Gy photon beam radiation therapy administered anteroposterior-posteroanterior in conjunction with chemotherapy with 5-fluorouracil and mitomycin C. Survival analysis was performed with the lifetest procedure.

RESULTS

In patients with stage T1 and T2 tumors, 26 of 29 (90%) were free of disease after chemotherapy and radiation therapy and had no recurrent tumors. In patients with stage T3 and T4 tumors, five of 13 (38%) were free of disease after therapy and had no recurrences.

CONCLUSION

This therapy is effective for epidermoid cancers of the anal canal that are smaller than 5 cm regardless of nodal status. Tumors larger than this or that invade adjacent structures are not adequately controlled with this protocol.

A convenient method for the determination of the solubility of hemoglobin and modified hemoglobins

The removal of a single charged group can drastically alter the solubility of hemoglobin. Alterations in hemoglobin structure to make it of potential use as a blood substitute must produce derivatives which are sufficiently soluble to allow adequate oxygen delivery. We have developed a convenient method for examining modified hemoglobins. How the polymerization of Hemoglobin S is perturbed in the presence of modified hemoglobins is determined. To measure Hemoglobin S polymerization, a rapid temperature jump from 0 degree and a nitrogen atmosphere [1] are not required. In pH 7.4 phosphate buffers at concentrations greater than 2M containing sodium dithionite, dilute solutions (less than 1 mg/ml) of hemoglobin S aggregate at 30 degrees, or higher, after a delay time (minutes) which depends on the hemoglobin concentration. Light scattering can be used to quantify the extent of polymerization. Chemical modifications of Hemoglobin A can result in altered perturbation of Hemoglobin S polymerization as determined by this method. Modification of hemoglobin to provide suitable oxygen binding characteristics and crosslinking of subunits is a required preliminary to use of hemoglobin as an acellular blood substitute. These modifications often involve the elimination of charged groups from hemoglobin. Information on whether such modifications may have undesirable consequences with respect to solubility properties can be examined using the method described.