A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors.

Most large (over a kilometre in diameter) near-Earth asteroids are now known, but recognition that airbursts (or fireballs resulting from nuclear-weapon-sized detonations of meteoroids in the atmosphere) have the potential to do greater damage than previously thought has shifted an increasing portion of the residual impact risk (the risk of impact from an unknown object) to smaller objects. Above the threshold size of impactor at which the atmosphere absorbs sufficient energy to prevent a ground impact, most of the damage is thought to be caused by the airburst shock wave, but owing to lack of observations this is uncertain. Here we report an analysis of the damage from the airburst of an asteroid about 19 metres (17 to 20 metres) in diameter southeast of Chelyabinsk, Russia, on 15 February 2013, estimated to have an energy equivalent of approximately 500 (±100) kilotons of trinitrotoluene (TNT, where 1 kiloton of TNT = 4.185×10(12) joules). We show that a widely referenced technique of estimating airburst damage does not reproduce the observations, and that the mathematical relations based on the effects of nuclear weapons--almost always used with this technique--overestimate blast damage. This suggests that earlier damage estimates near the threshold impactor size are too high. We performed a global survey of airbursts of a kiloton or more (including Chelyabinsk), and find that the number of impactors with diameters of tens of metres may be an order of magnitude higher than estimates based on other techniques. This suggests a non-equilibrium (if the population were in a long-term collisional steady state the size-frequency distribution would either follow a single power law or there must be a size-dependent bias in other surveys) in the near-Earth asteroid population for objects 10 to 50 metres in diameter, and shifts more of the residual impact risk to these sizes.

Effects of prenatal nutritional supplementation on the placenta: report of a randomized controlled trial.

Protein and nucleic acid content, and RNase levels were measured in placentas collected at birth in a randomized controlled trial of prenatal nutritional supplementation in New York City. These biochemical indices were explored to understand better the effects of nutritional supplementation. (With high-protein supplements, gross measures had shown no improvement in outcome at birth and adverse effects on fetal growth, prematurity, and newborn survival; with balanced protein-calorie supplements, there was a nonsignificant rise in birth weight and longer gestation.) The biochemical indices were in general somewhat weakly related to fetal growth measures. Significant effects of nutritional treatment on the indices were minimal, and added no information that could account for gross effects observed in the fetus.

Referral for menstrual problems: cross sectional survey of symptoms, reasons for referral, and management.

OBJECTIVES: To describe the menstrual experience of women referred for menstrual problems, in particular menorrhagia (excessive menstrual loss), and to assess associations with reasons for referral given by their general practitioners, the women's understanding of the reasons for their attendance at the hospital clinics, and clinic outcome. DESIGN: Questionnaire survey, with partial review of case notes after 8 months. SETTING: Three hospital gynaecology clinics in Glasgow and Edinburgh. PARTICIPANTS: 952 women completed the questionnaire, and the first 665 were reviewed. OUTCOME MEASURES: Reason for referral, women's reported menstrual problems and reason for clinic attendance, diagnosis, and treatment. RESULTS: Only 38% (95% confidence interval 34% to 41%) of women reported excessive menstrual loss as a severe problem. However 60% (57-63%) gave it as reason for attending a clinic, and 76% (73-79%) of general practitioners gave it as reason for referral. Reason for referral was significantly biased towards bleeding (McNemar odds ratio 4.01, 3.0 to 5.3, P<0.001) and against pain (0.54, 0.4 to 0.7, P<0.001). Dysfunctional uterine bleeding was diagnosed in 37% (31-42%) of the 259 women who gave as reason for attendance something other than bleeding. Women who were economically disadvantaged differed in prevalence of the main diagnoses and were more likely to fail to reattend. Hysterectomy was associated with referral for bleeding (relative risk 4.9, 1.6 to 15.6, P<0.001) but not with the patient stating bleeding as the reason for clinic attendance. CONCLUSIONS: Intolerance of the volume of their bleeding is not a key feature among women attending clinics for bleeding problems. Broad menstrual complaint tends to be reframed as excessive bleeding at referral and during management. This may result in women receiving inappropriate care. Conceptualisation and assessment of menorrhagia requires reconsideration.

Bacteriuria in pregnancy treated with a single dose of cephalexin.

Of 87 women in whom bacteriuria was diagnosed on dip slides at between 9 and 22 weeks gestation only 51 (59%) had true bacteriuria in urine obtained by suprapubic aspiration. A single oral dose of cephalexin (3 g) was given to 37 of these patients, 10 were Indian and none of them had recurrence of infection after treatment, whereas 11 of the 27 (41%) 'indigenous' women again had bacteriuria within 2 weeks of treatment. None of the other 26 patients had recurrent bacteriuria in the pregnancy studied. Success of treatment was not related to renal concentrating ability nor, apart from ethnic group, were there other significant differences between successes and failures. Although single-dose treatment seems to be less effective in pregnancy than in the non-pregnant patients, it is an acceptable method of treatment provided that all treated patients are followed closely to detect those who do not respond and require further therapy.

Scottish gynaecologists: their views on hormone replacement therapy.

In a postal questionnaire Scottish gynaecologists were asked their views on the use of Hormone Replacement Therapy (HRT). They were almost unanimous in support of HRT, but varied in the circumstances in which they would recommend it and in the length of time they would prescribe it. The need for designated Menopause Clinics was seen to be limited, with most smaller Units preferring the present practice of menopausal patients being seen at general Gynaecology Clinics. Most of those replying thought that General Practitioners (GPs) should continue to be the main providers of the therapy but 89 (77%) felt that Well Women/Family Planning Clinic (WW/FPC) doctors could be an alternative source. Several problems associated with the use of the therapy were indicated. These included uncertainties about the risks of long term use and the management of unscheduled vaginal bleeding, but there was also concern over the administrative and prescribing costs if the therapy is to be widely used as prophylactic medication.

GnRH analogue in everyday gynecology: is it possible to rationalize its use?

BACKGROUND: The study was an audit of patients who attended the Menstrual Disorders Clinic at Glasgow Royal Infirmary over a five year period, and received gonadotrophin-releasing hormone analog (GnRHa). We aimed to identify the clinical indications for the use of GnRHa, and the effect of the latter in terms of symptom resolution and ultimate outcome. We aim to use this information to formulate a strategy for the use of GnRHa by targeting this expensive therapy to those situations where maximum benefit will be achieved. METHODS: A retrospective case review analysis of 201 patients. RESULTS: Thirty-eight percent of women presented with pelvic pain, 33% with disordered menstruation and 26% with premenstrual symptomatology. Overall, 74% of patients reported a beneficial effect of GnRHa. In the non-cyclical pelvic pain group, those patients with adhesions constituted a much greater proportion of those who did not derive benefit from GnRHa than those who did (43% vs. 16%; p<0.05; data not shown). In those patients with disordered menses, there was no difference between the diagnosis in those who did or did not derive benefit from GnRHa. Also with the exception of endometrial preparation prior to ablation and in the correction of anemia, the ultimate outcome was no different in the two groups. Of the patients with premenstrual symptomatology, the greatest proportion of those deriving benefit from GnRHa (41%) ultimately had an operative resolution. CONCLUSIONS: Our results enable us to use GnRHa as a first line in those clinical situations where maximum benefit will be achieved, either in terms of symptom resolution or as a tool to identify the most appropriate therapeutic option. We can therefore rationalize our prescribing both to the benefit of the patient and to our budget.

Endometrial apoptosis in patients with dysfunctional uterine bleeding.

AIMS: To assess glandular apoptosis in the zona functionalis of proliferative phase endometrium in normal individuals and in patients with dysfunctional uterine bleeding (DUB). METHODS AND RESULTS: Routinely processed, haematoxylin and eosin-stained endometrial biopsies were assessed in 26 patients with symptomatic menstrual abnormality, mainly menorrhagia, and in 24 controls. All biopsies were in the proliferative phase and had been reported as within normal limits and consistent with the menstrual cycle dates provided. Apoptotic and mitotic figures were counted in a minimum of 100 transversely sectioned endometrial glands in all cases. In 16 biopsies (12 DUB and four controls) apoptosis was further assessed using the in situ terminal deoxynucleotidyl-transferase-mediated 2'-deoxyuridine-5'-triphosphate (dUTP) nick-end labelling (TUNEL) method. Apoptotic figures were identified in most control biopsies averaging 5.6/100 glands, and were significantly increased in biopsies from patients with DUB averaging 13.9/100 glands. There was no difference in mitotic figure counts. Apoptoses tended to be clustered within adjacent glands in both groups and individual glands exhibited both mitotic and apoptotic activity. Application of the TUNEL method gave broad agreement with morphological assessment although approximately 20-25% of typical apoptotic figures were not labelled. CONCLUSIONS: Endometrial glandular apoptosis is present in most normal proliferative phase biopsies and appears increased in some cases of DUB. The significance of this finding is not known but increased apoptosis may serve as a morphological marker of abnormal endometrial development in otherwise normal biopsy specimens.

Is screening for bacteriuria in pregnancy worth while?

A total of 4470 pregnant women were screened for bacteriuria by the dipslide method and significant growth found in 226 (5.1%). In 198 cases the urine was re-examined, in 119 by using suprapubic aspiration or catheterisation (62 (52%) samples contained bacteria) and in 79 by using midstream urine samples (26 (33%) samples contained greater than 10(8) colony forming units/1), showing the maximum prevalence of confirmed bacteriuria to be 2.6%. Overt urinary tract infection developed later in four of 80 patients with proved bacteriuria who had been given antibiotics, in one of eight untreated patients with bacteriuria, in one of 110 patients with unconfirmed bacteriuria, and in one of 226 non-bacteriuric controls. A history of urinary tract infection was given by 18% of controls and 42% of women with confirmed bacteriuria. Screening for bacteriuria and treatment with antibiotics to prevent later overt infection is expensive. Whether it is worth while and cost effective depends largely on the prevalence of bacteriuria in the local population and the proportion who develop overt infection. The screening and treatment programme reported here appeared to prevent only six cases of overt infection.

Single-dose treatment of bacteriuria in pregnancy.

Comparison of the results of single-dose treatment of urinary tract infection in women is confused by differences between published series in the duration of follow-up and in the diagnosis of infection. Pregnancy allows prolonged follow-up in a motivated population, but increases the possibility of false positive diagnosis of infection from midstream urines due to increased vulvovaginal contamination. Suprapubic aspiration (SPA) is safe in pregnancy and accurately confirms the presence or absence of bacteria in the bladder urine. Bacteriuria was diagnosed by SPA in 86 pregnant women. Thirty-seven of these were treated with a single dose of 3 g cephalexin and 49 with 3 days of cephalexin 1 g or of a combined preparation of pivmecillinam-pivampicillin. Both single-dose and 3-day treatments prevented further bacteriuria in 65% of the patients for the remainder of their pregnancies. This is similar to the results achieved with 10-day treatment. If extended trials confirm that single-dose treatment is as effective as conventional treatment with the same drug, then single-dose treatment has the advantages in pregnancy of minimal medication, good patient compliance and lack of side-effects.

Factors affecting birthweights in Hindus, Moslems and Europeans.

The birthweights of 664 Hindu and 132 Moslem babies were compared with those of 486 European babies born at the same hospital. The mean birthweight of the Europeans was 3362 g, compared with 3146 g for the Moslems and 2960 g for the Hindus. The Asian women were smaller than the European and tended to have a shorter length of gestation. Forty-four per cent of the Asians and 46% of the European mothers were of social classes I and II; 28% of the Europeans and 2% of the Asians smoked. There were no significant differences between Asians and Europeans in the effects of maternal size, parity, gestational age and fetal sex on birthweight. After adjustment for these variables and for cigarette smoking there was no significant difference in birthweight between the Moslems and the Europeans, but the mean birthweight of the Hindus was about 190 g lighter than that of the Europeans. Hindus from East Africa had lighter babies than those from India.

PIP: This study compared the birthweights of infants born to women of Hindu, Moslem, and European origin in a relatively affluent area of UK and examined the relationship between birthweight and other factors. The mean birthweight of the European infants was 3362 gm compared with 3146 gm for Moslems and 1960 gm for Hindus. The 796 Asian mothers were significantly smaller than the 486 European mothers and tended to have a shorter length of gestation. 42% of the variance was explained by the factors gestational age, maternal weight, maternal height, fetal sex, parity, and smoking. When birthweight was adjusted for all variables except smoking, the Moslem mean adjusted birthweight (3199 gm) was similar to that for Europeans (3192 gm), but the Hindu infants were significantly lighter (3074 gm). When smoking was included in the adjustment, the mean birthweight was 3234 gm for Europeans, 3191 gm for Moslems, and 3045 gm for Hindus. (28% of the European mothers and 2% of the Asian mothers smoked.) There awas no consistent relationship between birthweight and social class in the Asians, but there was a significant trend for Europeans in lower social classes to have smaller infants. Infants born to Hindu mothers from India were significantly heavier than those born to East Africans. It is unclear whether the approximately 190 gm lighter birthweight of Hindu infants compared with European infants is physiological or pathological. Further investigation of pregnancy outcome among ethnic and religious subgropus of the Asian population in the UK, as well as comparisons with the indigenous European population, are recommended to increase understanding of the factors that determine birthweights.

High-meat, low-carbohydrate diet in pregnancy: relation to adult blood pressure in the offspring.

To examine the hypothesis that a high-animal protein, low-carbohydrate diet in pregnancy is associated with raised blood pressure in the adult offspring, we performed a follow-up study of 626 men and women in Motherwell, Scotland, whose mothers' food intake had been recorded during pregnancy. The mothers had taken part in a dietary intervention in which they were advised to eat 1 lb (0.45 kg) of red meat per day and to avoid carbohydrate-rich foods during pregnancy. The offspring were followed up at age 27 to 30 years, and their systolic and diastolic blood pressures were measured. Women who reported greater consumption of meat and fish in the second half of pregnancy had offspring with higher systolic blood pressure in adult life (regression coefficient, 0.19 mm Hg per portion per week; 95% confidence interval, 0.04 to 0.35; P=0.02). High maternal consumption of fish, but not meat, was associated with higher diastolic blood pressure in the offspring (regression coefficient, 1.00 mm Hg per portion per week; 95% confidence interval, 0.18 to 1.82; P=0.02). These associations were independent of maternal blood pressure, body size, and smoking habits during pregnancy. Although we cannot exclude confounding by maternal saturated fat or salt intake, the findings support those of a study in Aberdeen showing higher blood pressure in men and women whose mothers had eaten a high-animal protein, low-carbohydrate diet in late pregnancy. These associations may reflect the metabolic stress imposed on the mother by an unbalanced diet in which high intakes of essential amino acids are not accompanied by the nutrients required to utilize them.

Diet during pregnancy in an Asian community in Britain--energy, protein, zinc, copper, fibre and calcium.

Dietary intake of 813 pregnant Harrow Asians of mainly Gujarati descent was compared with the intake of 54 pregnant Europeans living in the same area. The diet of the Europeans had more protein and zinc but less fibre and fat that that of the Harrow Asians. The average rate of weight gain and the energy intakes were similar in both groups. Hindu non-vegetarians and Muslim non-vegetarians differed somewhat, because the Hindus, who are more recent converts to meat-eating, have diets with a lactovegetarian basis to which small amounts of meat have been added. Among the Hindu vegetarians, those who ate eggs and cheese had higher protein and zinc intakes, but otherwise Hindu vegetarians can be regarded as a fairly homogeneous group. Although the protein and zinc intakes of the Asians, particularly the vegetarians, were lower than those of the Europeans, there was no evidence of adverse consequences to the mother and fetus.

Randomised comparative trial of the levonorgestrel intrauterine system and norethisterone for treatment of idiopathic menorrhagia.

OBJECTIVE: To compare the efficacy and acceptability of the levonorgestrel intrauterine system and norethisterone for the treatment of idiopathic menorrhagia. DESIGN: A randomised comparative parallel group study. SETTING: Gynaecology outpatient clinic in a teaching hospital. PARTICIPANTS: Forty-four women with heavy regular periods and a measured menstrual blood loss exceeding 80 ml. METHODS: Twenty-two women had a levonorgestrel intrauterine system inserted within the first seven days of menses, and 22 women received norethisterone (5 mg three times daily) from day 5 to day 26 of the cycle for three cycles. MAIN OUTCOME MEASURES: The main outcome measure was the change in objectively assessed menstrual blood loss after three months of treatment. RESULTS: When menstrual blood loss at three months was expressed as a percentage of the control, the levonorgestrel intrauterine system reduced menstrual blood loss by 94% (median reduction 103 ml; range 70 to 733 ml), and oral norethisterone by 87% (median reduction 95 ml; range 56 to 212 ml). After three cycles of treatment 76% of the women in the levonorgestrel intrauterine system group wished to continue with the treatment, compared with only 22% of the norethisterone group. CONCLUSIONS: Both the levonorgestrel intrauterine system and oral norethisterone in this regimen provided an effective treatment for menorrhagia in terms of reducing menstrual blood loss to within normal limits. The levonorgestrel intrauterine system was associated with higher rates of satisfaction and continuation with treatment, and thus offers an effective alternative to currently available medical and surgical treatments for menorrhagia.

PIP: The efficacy and acceptability of two new approaches to the treatment of idiopathic menorrhagia--the levonorgestrel intrauterine system and norethisterone--were compared in 45 women recruited from a gynecology outpatient clinic at a UK teaching hospital. All study participants had heavy regular periods and a measured menstrual blood loss exceeding 80 ml. 22 women were randomly assigned to have a levonorgestrel intrauterine system inserted within the first 7 days of menses and 22 women received 5 mg of norethisterone 3 times daily from day 5 to day 26 of their cycle for 3 cycles. Compared to baseline, the levonorgestrel intrauterine system reduced menstrual blood loss by 94% (median reduction, 103 ml) and oral norethisterone reduced it by 87% (median reduction, 95 ml). Recorded in both treatment groups were significant decreases in breast tenderness, mood swings, intermenstrual bleeding, and interferences in daily life caused by menstruation. After 3 treatment cycles, 64% of women in the levonorgestrel group indicated they liked the treatment "well" or "very well" and 77% elected to continue the regimen. In the norethisterone group, these rates were only 44% and 22%, respectively. Although both regimens reduced menstrual blood loss to within normal limits, the levonorgestrel intrauterine system was associated with higher satisfaction and thus offers an effective alternative to currently available medical and surgical treatments for menorrhagia.

Zinc and copper in Asian pregnancies--is there evidence for a nutritional deficiency?

In 92 Hindu Asians, 59% of them vegetarian, and 51 Europeans longitudinal measurements were made during pregnancy of the zinc and copper concentrations in plasma and hair together with urinary zinc excretion, as indices of their zinc and copper status. Maternal diets were assessed once at booking. Zinc intakes ranged from 3.1 to 16.9 mg/day, with average intakes least in vegetarian Hindus and most in Europeans. Average copper intakes ranged between 1.48 and 1.80 mg/day and were similar in the three patient groups. Both ethnic groups showed the pregnancy-associated fall in the plasma concentration of zinc and rise in that of copper but throughout the study Hindus had statistically significant lower levels of zinc and higher levels of copper than Europeans. Urinary zinc excretion was not only significantly lower throughout the study in Hindus than in Europeans but the increase in excretion which occurred after 20 weeks gestation was smaller. There were no ethnic differences in the zinc content of hair. Urinary zinc excretion correlated with both plasma zinc levels and dietary zinc. Mean birthweight in the Hindus was 2912 g and 34% of infants were below the 10th centile, using the Aberdeen standards, compared with 6% of the European babies (mean birthweight 3349 g). No association was found between crude or adjusted birthweight and any of the measures of zinc or copper status in either ethnic group. The Hindus had an apparently lower average zinc status than the Europeans, but there was no evidence that this had acted as a nutritional constraint and was the cause of their slower rate of intrauterine growth.

The effects of maternal cigarette smoking on placental morphology, histomorphometry, and biochemistry.

We related cigarette smoking during pregnancy to the macroscopic and microscopic morphology, histomorphometry, and biochemistry of the placenta among participants in The Prenatal Project, a randomized, controlled trial of nutritional supplementation during pregnancy. The aim was to ascertain if the harmful effects of cigarette smoking on the fetus were reflected, and possibly mediated, by changes in the placenta, and whether such changes might be modified by the nutritional supplements, parallel to the nutritional reversal of birthweight depression among heavy smokers. Maternal smoking was associated with increased alkaline ribonuclease (RNase) levels, possibly resulting in disturbed protein synthesis. More smokers had placentas with villous hyperplasia on histologic examination. This was accompanied by biochemical evidence of significantly increased cellularity (increased DNA/gm of placental mass and decreased protein/DNA ratios) and (nonsignificant) trends to reduced syncytial villous cell size on histomorphometry. There were joint effects of cigarette smoking and use of either form of nutritional supplementation on the fibrin and stoma components of the villi, but such changes are not necessarily pathologic. The significant reduction in pathology of the stem villi among smokers was confined to those who were nutritionally supplemented, particularly heavy smokers. This change may thus have reflected the protective effects of supplementation on the birthweight of the offspring of these heavy smokers.