Side-to-side differences in knee laxity and side hop test may predispose an anterior cruciate ligament reinjury in competitive adolescent alpine skiers

An anterior cruciate ligament (ACL) injury is a common, severe injury in alpine skiing, and anterior cruciate ligament reconstruction (ACLR) is frequently performed in competitive alpine skiers younger than 20 years old. To reduce the reinjury rate, both intrinsic and extrinsic risk factors should be examined. The aim of this study was to investigate possible intrinsic risk factors for an ACL reinjury in competitive alpine skiers. A cohort of 384 alpine skiers (191 males/193 females) from the Swedish ski high schools were prospectively followed during their high school years. The students were clinically examined and physically tested prior to each ski season. In addition, the RAND 36-Item health survey 1.0 (SF-36, Copyright 1994 Medical Outcome Trust, distributed by RAND Corporation) and injuries were prospectively registered. Thirty-one of the skiers (five males/26 females) had undergone an ACLR before entering the ski high school. This cohort was analyzed with respect to the occurrence of, and possible risk factors for an ACL reinjury (including ipsilateral and contralateral ACL injuries). Skiers who sustained an ACL reinjury were called the “ACL reinjury group,” and those who did not sustain an ACL reinjury were called the “ACL injury group.” Notably, 12 of the 31 students (39%), ten female and two male skiers, aged 16.5 (SD 0.5) years, sustained an ACL reinjury during the two first years at the ski high school. In addition, 10 of the 12 ACL reinjuries occurred within 10–23 months from the first injury [m 14.8 (SD4.7)] and two ACL reinjuries occurred at 29 and 47 months, respectively, from the first injury. It is noted that eight of the ACL reinjuries were to the ipsilateral knee and four to the contralateral knee. There were no differences between the groups with respect to muscle flexibility in the lower extremity, Beighton score, and one leg hop for distance or square hop test. Side-to-side differences were found with respect to knee joint laxity, >3 mm, measured with KT-1000 arthrometer (p = 0.02), and the side hop test (p = 0.04). RAND 36-Item health survey did not predict an ACL reinjury. In conclusion, a side-to-side difference in the side hop test and knee joint laxity (KT-1000) may predispose an ACL reinjury in competitive adolescent alpine skiers.

A screening instrument for side dominance in competitive adolescent alpine skiers

Previous research has shown that high school ski students injure their left anterior cruciate ligament (ACL) more often than their right ACL, and that a prevention program focusing on equal load to the right and left ski turns prevents ACL injuries. Whether the injuries were in the dominant or non-dominant side of ski students was not determined but may be important knowledge to ski coaches for future design of ski-specific training programs. There is no gold standard on how to investigate the dominant side of alpine skiers. Therefore, the aim of this study was to develop a screening instrument consisting of five questions for identifying side dominance and to evaluate side dominance in competitive adolescent alpine skiers. First, 121 competitive adolescent alpine skiers answered the questions on side dominance using a test-retest design. The questions were: which hand/arm (left/right) or foot/leg (left/right) one uses as the first choice when writing, throwing, kicking a ball, jumping over a fence and stair-climbing. A question about safer/better ski turn to the left or to the right was also added. Second, 274 skiers answered the questions at one occasion. A very good agreement was shown in writing and throwing and kicking a ball, and a fair agreement was shown in jumping over a fence and stair climbing. A total of 243 skiers reported right-sided dominance, and seven skiers reported left-sided dominance. One hundred and nineteen of the 121 skiers who took part in the test-retest design answered the question safer/better ski turn, and of those 70 (59%) reported that they had a safer/better ski turn to one side than to the other side. However, the side was not consistent between the two test occasions, and the question did not correlate with side dominance. A combination of the three questions “What hand/arm do you use as first choice when writing?” “What hand/arm do you use as first choice when throwing?” and “What foot/leg do you use as first choice when kicking a ball?”, may be used to decide side dominance in adolescent alpine skiers. Most adolescent alpine skiers reported right-sided dominance.

Prevention of Anterior Cruciate Ligament Injuries in Competitive Adolescent Alpine Skiers

Anterior cruciate ligament (ACL) injury is one of the most serious injuries among Swedish alpine ski high school students. An ACL injury forces the skier to stop skiing for several months, and some skiers even have to give up their skiing career. Therefore, an ACL injury prevention program might play an important role for alpine skiers. In the present study ski high school students have been followed in terms of ACL injuries during 1-2 ski seasons between 2006/2007 and 2012/2013. Alpine skiers studying at the Swedish ski high schools during the ski seasons 2011/2012 and 2012/2013 received a specific ACL injury prevention program (n = 305), while alpine skiers who attended a Swedish ski high school between the ski seasons 2006/2007 and 2010/2011 served as controls (n = 431). The prevention program was based on earlier studies and included indoor and outdoor exercises on snow focusing on core stability and neuromuscular control. Alpine skiing is an equilateral sport. Therefore, the goal of the prevention was to encourage the skiers to practice these exercises in order to perform equally good on both legs. The outcome measure consisted of the number and incidence of ACL injuries. The 2 years of prevention resulted in 12 ACL injuries (3.9%) compared with 35 ACL injuries during the control period (8.1%). The absolute risk rate showed a decreased incidence rate of -0.216 [CI -0.001-(-0.432)]/100 months attending a ski high school in favor of the intervention group. A prevention program focusing on the skier's ability to perform neuromuscular exercises equally good on both legs led to a reduction of ACL injuries.

Risk Factors for Anterior Cruciate Ligament Injury in Competitive Adolescent Alpine Skiers

Background:

There is a high risk for anterior cruciate ligament (ACL) injuries in alpine skiers. To reduce or try to prevent these injuries, intrinsic and extrinsic risk factors need to be identified.

Purpose:

To identify possible intrinsic and extrinsic ACL injury risk factors among competitive adolescent alpine skiers.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Between 2006 and 2009, a cohort of 339 alpine ski students (176 male, 163 female) from Swedish ski high schools were prospectively observed in terms of ACL injuries. First-time ACL injuries were recorded. In September, prior to each ski season, the skiers were clinically examined according to a specific knee protocol.

Results:

Overall, 11 male and 14 female skiers sustained a total of 25 first-episode ACL injuries. The majority of injuries occurred in the left knee (P < .05). Skiers who had participated in alpine skiing for >13 years (hazard ratio, 0.83; 95% CI, 0.68-1.00; P < .05) had a reduced risk of sustaining an ACL injury. Eighteen ACL injuries occurred during training, 12 in the technical discipline of giant slalom, and 8 in slalom. Fourteen skiers reported not to be fatigued at all at the time of injury, and 8 skiers reported that they were somewhat fatigued.

Conclusion:

ACL injuries occurred more often in the left knee than the right. This should be taken into consideration in the design of ACL injury prevention programs. Those who reported a higher number of active years in alpine skiing showed a reduced risk of sustaining an ACL injury. No other factor among those studied could be identified as an independent risk factor for ACL injury.

The correlation between anterior cruciate ligament injury in elite alpine skiers and their parents

PURPOSE

The aim of this study was to investigate whether a familiar correlation with anterior cruciate ligament (ACL) injury exists between competitive alpine skiers and their parents.

METHODS

All 593 (293 males, 300 females) elite alpine skiers who have studied at a Swedish alpine Ski High School during 2006 and 2012 answered a questionnaire whether they or their parents had suffered an ACL injury. A total of 418 skiers (70%) answered the questionnaire.

RESULTS

Twenty-nine per cent (n = 19) out of the 65 ACL-injured skiers reported that they had a parent (mother or father) who have had an ACL injury. In skiers without an ACL injury (n = 353), the result was 18% (n = 64). An odds ratio of 1.95 (95% confidence interval 1.04-3.65) was found to suffer an ACL injury if you have a parent who has had an ACL injury compared with if you have a parent without any ACL injury.

CONCLUSION

The findings of the current study demonstrated a family history to tear the ACL between alpine skiers who had studied at a Swedish Ski High School and ACL injuries of their parents.

LEVEL OF EVIDENCE

III.

Experiences of returning to elite alpine skiing after ACL injury and ACL reconstruction

AIM

To explore the experiences of alpine skiing at the elite level after anterior cruciate ligament (ACL) injury and reconstruction.

DESIGN

A qualitative approach where semi-structured interviews were conducted, and an analysis of the manifest content was performed.

PARTICIPANTS

Five ski high school students, two male and three female skiers, who had suffered ACL injuries and undergone ACL reconstructions.

RESULTS

Seven categories were identified. The participants described their perceived opportunities with regard to returning to alpine skiing after ACL injury and reconstruction as something positive to do with self-belief, being mentally and physically prepared, regaining confidence in their own ability, being given time and using active strategies. In contrast, perceived barriers to a return to elite alpine skiing gave rise to negative feelings, for example, fear, disheartenment, a total lack of or ambivalent confidence in their own ability and the use of passive strategies.

CONCLUSION

The two male skiers returned to alpine skiing. They reported confidence in their own ability, active strategies and support on all levels, as well as enhanced physical ability. The female skiers did not return to their pre-injury level of competitive alpine skiing. They stated a lack of support on all levels, deterioration in their physical ability and two out of three reported passive strategies and no or ambivalent confidence in their own ability. The most important factors were family support, support on all levels, access to a physiotherapist and time given.

Primary prevention of childhood obesity through counselling sessions at Swedish child health centres: design, methods and baseline sample characteristics of the PRIMROSE cluster-randomised trial

BACKGROUND

Childhood obesity is a growing concern in Sweden. Children with overweight and obesity run a high risk of becoming obese as adults, and are likely to develop comorbidities. Despite the immense demand, there is still a lack of evidence-based comprehensive prevention programmes targeting pre-school children and their families in primary health care settings. The aims are to describe the design and methodology of the PRIMROSE cluster-randomised controlled trial, assess the relative validity of a food frequency questionnaire, and describe the baseline characteristics of the eligible young children and their mothers.

METHODS/DESIGN

The PRIMROSE trial targets first-time parents and their children at Swedish child health centres (CHC) in eight counties in Sweden. Randomisation is conducted at the CHC unit level. CHC nurses employed at the participating CHC received training in carrying out the intervention alongside their provision of regular services. The intervention programme, starting when the child is 8-9 months of age and ending at age 4, is based on social cognitive theory and employs motivational interviewing. Primary outcomes are children's body mass index and waist circumference at four years. Secondary outcomes are children's and mothers' eating habits (assessed by a food frequency questionnaire), and children's and mothers' physical activity (measured by accelerometer and a validated questionnaire), and mothers' body mass index and waist circumference.

DISCUSSION

The on-going population-based PRIMROSE trial, which targets childhood obesity, is embedded in the regular national (routine) preventive child health services that are available free-of-charge to all young families in Sweden. Of the participants (n = 1369), 489 intervention and 550 control mothers (75.9%) responded to the validated physical activity and food frequency questionnaire at baseline (i.e., before the first intervention session, or, for children in the control group, before they reached 10 months of age). The food frequency questionnaire showed acceptable relative validity when compared with an 8-day food diary. We are not aware of any previous RCT, concerned with the primary prevention of childhood obesity through sessions at CHC that addresses healthy eating habits and physical activity in the context of a routine child health services programme.

TRIAL REGISTRATION

ISRCTN16991919.

Psychological treatment of dental anxiety among adults: a systematic review

The aim was to investigate the efficacy of behavioural interventions as treatment of dental anxiety/phobia in adults, by conducting a systematic review of randomized controlled trials (RCTs). The inclusion criteria were defined according to the Patients, Interventions, Controls, Outcome (PICO) methodology. The study samples had documented dental anxiety, measured using validated scales [the Dental Anxiety Scale (DAS) or the Dental Fear Survey (DFS)], or fulfilled the psychiatric criteria for dental phobia. Behavioural interventions included were based on cognitive behavioural therapy (CBT)/behavioural therapy (BT), and control conditions were defined as information, sedation, general anaesthesia, and placebo/no treatment. The outcome variables were level of dental anxiety, acceptance of conventional dental treatment, dental treatability ratings, quality of life and oral health-related quality of life, and complications. This systematic review identified 10 RCT publications. Cognitive behavioural therapy/behavioural therapy resulted in a significant reduction in dental anxiety, as measured using the DAS (mean difference = -2.7), but the results were based on low quality of evidence. There was also some support that CBT/BT improves the patients' acceptance of dental treatment more than general anaesthesia does (low quality of evidence). Thus, there is evidence that behavioural interventions can help adults with dental anxiety/phobia; however, it is clear that more well-designed studies on the subject are needed.

Injury profile of competitive alpine skiers: a five-year cohort study

PURPOSE

The aim of this study was to make a survey of injuries in young elite alpine skiers.

METHODS

During 5 years, all students at the Swedish Ski High schools were prospectively followed regarding injuries, time of exposure, injury location, type of injury, injury severity and gender. Four hundred and thirty-one skiers, 215 males and 216 females completed the entire study.

RESULTS

Of 431 skiers, 193 (91 males, 102 females) sustained 312 injuries during the 5-year study period. The injury incidence for males was 1.62 injuries/1,000 ski hours or 2.97 injuries/100 months at a Ski High school, and the corresponding values for females were 1.77 and 3.25, respectively. Forty-one percent of the injuries involved the knee, 69% were ligament injuries, and 49% were classified as severe injuries. Of 190 injured skiers, 120 injured their left leg (P = 0.0097). This was their first time injury. The risk of sustaining a re-injury or a new injury increased the sooner the first time injury occurred (P = 0.001).

CONCLUSION

There was a high risk for alpine ski students to sustain an injury during their education at the Swedish Ski High schools. Most injuries, especially ligament injuries, occurred in the knee joint in both males and females. Both genders were more likely to sustain injuries to the left than to the right leg. Nearly 50% of the injuries were classified as severe.

LEVEL OF EVIDENCE

II.

Miscarriage after a normal scan at 12-14 gestational weeks in women at low risk of carrying a fetus with chromosomal anomaly according to nuchal translucency screening

OBJECTIVES

To estimate the risk of second-trimester miscarriage in women with low risk of carrying a fetus with chromosomal abnormality, according to nuchal translucency (NT) screening, and to determine whether NT thickness or other factors affect the risk.

METHODS

The study population comprised 14 278 singleton pregnancies with a risk of Down syndrome < 1:250 at NT scan, and where no fetal karyotyping was performed < 25 weeks. Risk factors for miscarriage were investigated by logistic regression.

RESULTS

The median risk of Down syndrome was 1 : 3138 (range 1 : 9651-1 : 251) and median NT was 1.7 (range 0.4-3.0) mm. The miscarriage rate was 0.5% (77/14 278; 95% CI 0.4-0.6). After having controlled for maternal age, we found the number of previous deliveries and miscarriages to independently predict miscarriage: odds ratio (OR) for each previous delivery 1.48, 95% CI 1.22-1.94, P < 0.0001; OR for each previous miscarriage 1.34, 95% CI 1.07-1.68, P = 0.01. Excluding women with any previous miscarriage and adjusting for parity, we found a U-shaped relationship between maternal age and miscarriage (P = 0.04).

CONCLUSION

In singleton pregnancies with estimated risk of Down syndrome < 1:250 according to NT screening at 12-14 weeks, the spontaneous fetal loss rate before 25 weeks is likely to be around 0.5%. NT thickness up to 3 mm does not seem to affect the risk of miscarriage in such pregnancies. Instead, the risk seems to increase with number of previous miscarriages and deliveries, and possibly the risk is highest in the youngest and oldest women.

By how much does increased nuchal translucency increase the risk of adverse pregnancy outcome in chromosomally normal fetuses? A study of 16,260 fetuses derived from an unselected pregnant population

OBJECTIVE

In this study we aimed to estimate the magnitude of a possible increase in risk of adverse outcome in fetuses with normal karyotype and increased nuchal translucency (NT), and to determine how well NT measurements can distinguish between fetuses with normal and adverse outcome.

METHODS

We studied 16,260 consecutive fetuses with normal karyotype derived from an unselected pregnant population. The following cut-offs for increased risk of adverse outcome were chosen a priori: NT > or = 95th percentile, > or = 3 mm, > or = 3.5 mm, and > or = 4.5 mm. The positive and negative likelihood ratios (+LR, - LR) of the risk cut-offs with regard to fetal malformation, miscarriage, perinatal death, termination of pregnancy and total adverse outcome were calculated, and receiver-operating characteristics (ROC) curves were drawn.

RESULTS

The total rate of adverse outcome was 2.7%. + LR and - LR of NT > or = 3.0 mm were: for lethal or severe malformation, + LR 15.0 (95% CI 7.0-28.6), - LR 0.89 (95% CI 0.81-0.95); for malformation of at least intermediate severity, + LR 8.1 (95% CI 4.3-14.0), - LR 0.95 (95% CI 0.92-0.97); for termination of pregnancy, + LR 41.6 (95% CI 17.1-86.6), - LR 0.67 (95% CI 0.41-0.85); for any adverse outcome, + LR 6.4 (95% CI 3.4-11), - LR 0.96 (95% CI 0.94-0.98). The odds for these adverse outcomes increased with increasing NT. NT > or = 3 mm did not significantly increase the risk of miscarriage or perinatal death. Areas under ROC curves for NT were small, with 95% CI below or only slightly above 0.5.

CONCLUSION

Our likelihood ratios can be used to calculate the individual risk of unfavorable outcome, but NT screening cannot reliably distinguish between normal and adverse outcome in fetuses with normal karyotype.

Routine ultrasound examination at 12 or 18 gestational weeks for prenatal detection of major congenital heart malformations? A randomised controlled trial comprising 36,299 fetuses

OBJECTIVE

To compare the rate of prenatal diagnosis of heart malformations between two policies of screening for heart malformations.

DESIGN

Randomised controlled trial.

SETTING

Six university hospitals, two district general hospitals.

SAMPLE

A total of 39 572 unselected pregnancies randomised to either policy.

METHODS

The 12-week policy implied one routine scan at 12 weeks including measurement of nuchal translucency (NT), and the 18-week policy implied one routine scan at 18 weeks. Fetal anatomy was scrutinised using the same check-list in both groups, and in both groups, indications for fetal echocardiography were ultrasound findings of any fetal anomaly, including abnormal four-chamber view, or other risk factors for heart malformation. In the 12-week scan group, NT >or=3.5 mm was also an indication for fetal echocardiography.

MAIN OUTCOME MEASURE

Prenatal diagnosis of major congenital heart malformation.

RESULTS

In the 12-week scan group, 7 (11%) of 61 major heart malformations were prenatally diagnosed versus 9 (15%) of 60 in the 18-week scan group (P= 0.60). In four (6.6%) women in the 12-week scan group, the routine scan was the starting point for investigations resulting in a prenatal diagnosis versus in 9 (15%) women in the 18-week scan group (P=0.15). The diagnosis was made <or=22 weeks in 5% (3/61) of the cases in the 12-week scan group versus in 15% (9/60) in the 18-week scan group (P=0.08).

CONCLUSIONS

The prenatal detection rate of major heart malformations was low with both policies. The 18-week scan policy seemed to be superior to the 12-week scan policy, although the differences in prenatal detection rates were not statistically significant.

Is measurement of nuchal translucency thickness a useful screening tool for heart defects? A study of 16,383 fetuses

OBJECTIVE

To determine the performance of nuchal translucency thickness (NT) measurement as a screening method for congenital heart defects (CHD) among fetuses with normal karyotype.

METHODS

An NT measurement was made in 16 383 consecutive euploid fetuses derived from an unselected pregnant population. The cut-offs for increased risk of heart defects, chosen a priori and tested prospectively, were: NT >or= 95th centile for crown-rump length, NT >or= 3 mm, and NT >or= 3.5 mm. The sensitivity and false-positive rate (FPR; 1 minus specificity) of the risk cut-offs and their positive and negative likelihood ratios (+LR and -LR) with regard to CHD were calculated.

RESULTS

Among the 16 383 fetuses with an NT measurement there were 127 cases with a diagnosis of heart defect confirmed by cardiac investigations after birth or at autopsy. Of these, 55 defects were defined as major, of which 52 were isolated (no other defects or chromosomal aberrations), corresponding to a prevalence of major heart defects in chromosomally normal fetuses/newborns of 3.3/1000. The sensitivity, FPR, +LR and -LR for NT >or= 95th centile with regard to an isolated major heart defect were: 13.5%, 2.6%, 5.2 and 0.9, respectively. For NT >or= 3.0 mm these values were: 9.6%, 0.8%, 12.0 and 0.9, and for NT >or= 3.5 mm they were: 5.8%, 0.3%, 19.3 and 0.9.

CONCLUSIONS

NT measurement is a poor screening method for isolated major CHD. A method with a much higher detection rate and with a reasonably low FPR is needed. However, increased NT indicates increased risk of fetal heart defect, and women carrying fetuses with increased NT should be offered fetal echocardiography in the second trimester.

Sensory denervation with capsaicin does not influence the critical ischemia time in rat island flaps

Capsaicin causes release and long-term depletion of neuropeptides from sensory neurons. Recently, critical rat pedicle flaps pretreated with capsaicin have shown decreased survival. In the present study, the effect of systemic capsaicin pretreatment on the no-reflow phenomenon was investigated in the rat. Effective depletion of neuropeptides was confirmed with functional tests and immunohistochemistry. Groin island flaps were exposed to 4, 6, 8, 10 or 12 hours of warm ischemia, and flap survival was judged one week postoperatively. In contrast to previously reported negative effects on pedicle flap survival after pretreatment with capsaicin, the present study showed no difference in flap survival between capsaicin-pretreated rats and controls. It is concluded that depletion of neuropeptides from sensory neurons does not have negative effects on the tissue's ability to withstand prolonged complete ischemia. As this contrasts with the findings in critical pedicle flaps, the influence of sensory neuropeptides and the necrosis mechanisms are likely to be different in these two types of ischemic conditions.

Immunological studies on the incorporation of radioactive leucine into sea urchin embryonic proteins: extractability and turn-over of newly synthesized proteins

This study was undertaken in order to investigate the turn-over of newly synthesized sea urchin embryonic proteins, the distribution of these proteins in the cell and their changes in solubility with time. Refined immunological methods providing unique possibilities for studies of individual proteins were utilized. The proteins were obtained in two soluble fractions: a concentrate of proteins from the cytosol was obtained by homogenization in a hypotonic medium and another fraction constituting membrane-associated proteins was solubilized by detergent treatment of the residual pellet; 75% of the total protein content in early and 60% in later developmental stages was thus solubilized. The proteins solubilized by these mild methods retained their antigenicity and could be analyzed by immunodiffusion methods. The fate of newly synthesized embryonic proteins was studied by incorporation of a radioactive amino acid using two different incubation procedures. The results of these studies indicated that newly synthesized proteins changed their solubility properties with time. Proteins were thus transfered from the soluble to the insoluble fraction. The findings that more proteins became insoluble during development mentioned above also supports such an interpretation. The synthesis of individual proteins was studied by immunodiffusion and autoradiography. Most of the antigens in the two soluble fractions were identical. Experiments with absorbed antisera revealed that only two to four antigens were present exclusively in one of the two soluble fractions. Three groups of antigens differing in regard to their metabolic activities were distinguished. Some antigens were labeled after both procedures without substantially increasing in concentration during development. Thus, their labeling was probably sustained by turn-over. Other antigens were labeled only after one of the two incubation procedures indicating large variations in regard to synthesizing rates of individual proteins.

Phosphatase active antigens in sea urchin eggs and embryos. I. Substrate specificity, pH-optima and inhibitors

Phosphatase activity in sea urchin embryonic antigens was investigated by histochemical staining of immunoprecipitates separated by two-dimensional (crossed) immunoelectrophoresis. Unfertilized eggs were homogenized in a hypotonic medium which solubilized cytoplasmic antigens. Antigens integrated in membranes or enclosed in particles were solubilized by detergent treatment of the residual pellet. Two different phosphatase activities were discerned in the unfertilized eggs, nucleoside diphosphatase (EC 3.6.1.6.) and acid phosphatase (EC 3.1.3.2.). Nucleoside diphosphatase activity was obtained in both the water soluble and detergent extracted protein fractions. This activity was confined to one antigen. Acid phosphatase acitivity on the other hand was almost exclusively obtained in the detergent extracted fraction and about ten distinct antigens displayed this activity. The nucleoside diphosphatase active antigen preferentially hydrolyzed purine nucleoside diphosphates and to a lesser degree triphosphates of these nucleosides. The acid phosphatase active antigens had a broader substrate specificity and hydrolyzed equally well beta-glycerophosphate and nucleotides. Both activities were essentially inactive at neutral or alkaline pH values. The activities were inhibited by p-choloromercuribenzoate and accordingly stimulated by cysteine. Tartrate and sodium fluoride, however, inhibited the acid phosphatase activity while nucleoside diphosphatase activity was either stimulated or not affected at all by these agents.

Phosphatase active antigens in sea urchin eggs and embryos. II. A comparison between the activities in unfertilized eggs and plutei

Phosphatase activities in sea urchin eggs and plutei were investigated by means of histochemical staining of immunoprecipitates. Two protein fractions were obtained by extraction in a hypotonic medium and by detergent treatment of the residual pellet. Three distinctly different phosphatase activities were discerned, nucleoside diphosphatase (EC 3.6.1.6.), acid phosphatase (EC 3.1.3.2.) and alkaline phosphatase (EC 3.1.3.1.). The nucleoside diphosphatase activity, which was confined to one antigen, was present in both water soluble and detergent extracts and at roughly the same concentration in eggs and plutei. By means of a monospecific antiserum the immunological identify of this antigen was established in all instances. The acid phosphatase activity, which was displayed by ten detergent extracted antigens in eggs, was only found in five detergent extracted antigens in plutei. This decrease in number of enzyme active antigens was also reflected by a general decrease in number of enzyme active antigens was also reflected by a general decrease in activity as assessed by quantitative determinations. Furthermore, by means of absorbed antisera it was established that two or three of the acid phosphatase active antigens were "egg specific". Another acid phosphatase active antigen, which was common to both developmental stages, was investigated by a monospecific antiserum. While this antigen was found in both soluble fractions, it was only enzymatically active when extracted with detergent. Alkaline phosphatase active antigens were only found in the detergent extract of plutei. However, immunoprecipitates with this activity appeared both with antiserum against unfertilized eggs and with antiserum against plutei. This suggests that the egg contained the antigens in an enzymatically inactive form.