Evaluation of digit ratio (2D:4D) in breast cancer patients.

Breast cancer is a hormone-dependent cancer. Hormonal exposure begins in the intrauterine period and continues in later years of life. 2D:4D ratio is accepted as an indicator of this exposure. The aim of this study was to investigate whether there is a difference in 2D:4D ratio between pathological subgroups of breast cancer and healthy control group. In this study, 204 participants, 154 breast cancer patients and 50 healthy control volunteers with similar age distribution, were included. Both hands of all participants were scanned using a digital scanner. The second and fourth finger lengths were measured using a digital measuring ruler with an accuracy of 0.05 mm. The 2D:4D ratio was calculated as the length of the second finger divided by the length of the fourth finger. A total of 204 patients (55 triple negative, 52 luminal B, 33 luminal A, 14 HER2-overexpessing and 50 healthy control volunteers) were subjected to finger scanning. There was no statistically significant difference in mean age between the groups. The right hand 2D:4D ratio was significantly lower in the Luminal A group compared to the other groups (p < 0.048). Although prenatal hormonal exposure is accepted as a risk factor for breast cancer, no study has evaluated patients in pathological subgroups. The 2D:4D ratio may be associated with breast cancer especially in the luminal A group in which hormone receptors are strongly positive and which has a better prognosis compared to the other groups.

2D/4D Finger Length Ratio in the Screening of Developmental Dysplasia of the Hip.

OBJECTIVE: To investigate whether there is a relationship between the 2nd finger and 4th finger length measurement ratios and developmental dysplasia of the Hip (DDH). STUDY DESIGN: Cross-sectional observational study. Place and Duration of the Study: Department of Orthopaedics and Traumatology, Meram Faculty of Medicine Hospital, Konya, Turkiye, from January 2020 to May 2023. METHODOLOGY: Infants were screened for DDH with Graff method for the ultrasounds of both hips. Lengths of the 2nd and 4th fingers of both hands were measured and recorded. Patients with additional risk factors for developmental dysplasia of the hip (breech birth, family history, oligohydramnios, swaddling) were excluded. RESULTS: Two hundred and fifty-six babies were screened including 55.1% (n = 141) girls and 44.9% (n = 115) boys. Their mean age was 2.51 ± 0.80 months. The average lengths were 31.73 ± 3.05 mm, for the left 2nd finger and 34.26 ± 3.48 mm for the left 4th finger. In the hip USG measurements, the mean alpha angles were 62.91 ± 3.12° for the right hip and, 63.20 ± 3.55° for the left hip. Eighteen (7%) of babies who underwent hip ultrasound (USG) had unilateral or bilateral DDH. Among these cases, 2.7% (n = 7) had right, 2.3% (n = 6) had left, and 2% (n = 5) had bilateral DDH. There was no statistically significant correlation between the ratios of right 2/4 finger lengths and the right alpha angle (rs = 0.051; p = 0.421). There was a statistically positive and statistically significant correlation between the ratios of left 2/4 finger lengths and the left alpha angle (rs = 0.154; p = 0.013). CONCLUSION: Only the left-hand finger ratio among the parameters in the model had a statistically significant effect on DDH. Therefore, the left hand 2D/4D finger length may be of value in screening for DDH. KEY WORDS: Developmental dysplasia of the hip, Second to fourth finger digit ratio, Ring finger, Digit ratios.

Is digit ratio (2D:4D) a biomarker for lactate? Evidence from a cardiopulmonary test on professional male footballers.

BACKGROUND: Lactate accumulation is associated with vigorous exercise, cardiovascular disease and a number of cancers. Digit ratio (2D:4D) has also been linked to oxygen metabolism, myocardial infarction and various cancers. Such similarities suggest the possibility that 2D:4D is a biomarker of lactate. Here, we consider the relationship between 2D:4D and lactate during an incremental cardiopulmonary exercise test. METHOD: The participants were male professional football players. The treadmill test began at a speed of 8 km/h when the first lactate measurement was taken. The speed was increased by 2 km/h every 3.15 min, with measurements at 10, 12, 14 and 16 km/h. RESULTS: There were 72 Caucasian and 7 Black participants, results are reported for the most numerous group. Lactate levels increased with running speed and were not correlated with age, body size or body composition. Median splits of digit ratios (right, left and right-left 2D:4D [Dr-l]) were calculated. In comparison to the Low ratio group, the High ratio group showed higher lactate levels across speeds. Effect sizes varied from very large to huge (right 2D:4D), large (left 2D:4D) and medium (Dr-l). At the individual level, positive correlations between digit ratios and lactate at the five different speeds varied from large (right 2D:4D), medium (left 2D:4D) and small (Dr-l). CONCLUSION: There were large positive associations between right 2D:4D and lactate at all running speeds. We discuss our findings in relation to oxygen metabolism and suggest that 2D:4D may be a biomarker for lactate in the wider context of the latter's importance in health and disease.

Can the Second and Fourth Finger (2D: 4D) Ratio Guide Physicians in Choosing Internal Medicine or Surgical Branch? / ¿Puede la proporción del Segundo y Cuarto Dedo (2D: 4D) Guiar a los Médicos en la Elección de Medicina Interna o Rama Quirúrgica?

SUMMARY: This study investigates the relationship between the second and fourth finger ratio (2D:4D), physicians' propensity to choose an internal or surgical branch, and sex differences. On a voluntary basis, 177 physicians working in Elazig, 122 men and 55 women were enrolled in the study. Their hands were measured for 2D and 4D lengths, and the 2D:4D ratio was computed. In female doctors, the left hand's 2D:4D ratio is 1.01, compared to the right hand's 1.00. Male doctors' right 2D:4D ratio is 0.99, while their left 2D:4D ratio is 1.00. Male physicians' 2D:4D ratios were different from those of men in the general population, whereas female physicians' 2D:4D ratios were comparable to those of women in the general population. As a result, this study was the first to examine the relationship between the ratio of the second and fourth fingers (2D:4D), physicians' tendency to choose an internal medicine or surgical branch, and sex differences. While the 2D:4D ratio was higher than 0.98 in all physicians, it was low in women who disliked their profession and branch. Since there aren't many studies on this subject, data from in-depth studies that will be conducted in the future will help physicians who choose internal medicine and surgery make more informed decisions.

Este estudio investiga la relación entre la proporción de los dedos segundo y cuarto (2D:4D), la propensión de los médicos a elegir una rama interna o quirúrgica y las diferencias de género. De forma voluntaria, se inscribieron en el estudio 177 médicos que trabajaban en Elazig, 122 hombres y 55 mujeres. Sus manos se midieron en longitudes 2D y 4D, y se calculó la relación 2D:4D. En las médicos mujeres, la relación 2D:4D de la mano izquierda es 1,01, en comparación con 1,00 de la mano derecha. La relación 2D:4D derecha de los médicos hombres fue 0,99, mientras que la relación 2D:4D izquierda fye 1,00. Las proporciones 2D:4D de los médicos hombres fueron diferentes de las de los hombres en la población general, mientras que las proporciones 2D:4D de las mujeres médicas fueron comparables a las de las mujeres en la población general. Como resultado, este estudio fue el primero en examinar la relación entre la proporción del segundo y cuarto dedo (2D:4D), la tendencia de los médicos a elegir una rama de medicina interna o quirúrgica y las diferencias de sexo. Mientras que la relación 2D:4D fue superior a 0,98 en todos los médicos, fue baja en las mujeres que no les gustaba su profesión y rama. Dado que no hay muchos estudios sobre este tema, los datos de estudios en profundidad que se realizarán en el futuro ayudarán a los médicos que eligen medicina interna y cirugía a tomar decisiones más informadas.

Digit ratio (2D:4D), laryngeal cancer and vocal fold leukoplakia.

BACKGROUND: To date, there are no studies that have analyzed the possible influence of exposure to prenatal sex hormones on the risk of laryngeal cancer (LC) and premalignant laryngeal lesion-vocal fold leukoplakia (VFL). Digit ratio (2D:4D) is suggested to be a proxy of prenatal sex hormone exposure. OBJECTIVE: To examine 2D:4D in patients with LC and clarify if it could add to the verified risk factors in estimating the overall risk of LC. METHODS: 511 subjects participated in the study. The study group included 269 patients: with LC (N = 114, 64 men) and VFL (N = 155, 116 men). Controls included 242 healthy individuals (66.40 ± 4.50 years (106 men)). RESULTS: Predictive models estimating the risk of VFL and LC in women, based solely on predictors like smoking and alcohol consumption had a lower area under the ROC curve (AUC) than the model with left 2D:4D. AUC for the model estimating the likelihood of VFL increased from 0.83 to 0.85, and for LC from 0.76 to 0.79. CONCLUSIONS: Low left 2D:4D may be associated with an increased risk of developing leukoplakia and laryngeal cancer in women. In the case of laryngeal cancer, left 2D:4D may serve as additional variable (to other known risk factors, such as smoking and/or alcohol consumption), which can improve cancer risk prediction.

The association of prenatal amniotic sex hormones and digit ratio (2D:4D) in children aged 5 to 70 months: A longitudinal study.

The sex difference of the 2D:4D digit ratio (female > male)-a proposed marker for prenatal testosterone exposure-is well established. Studies suggest it already exists in utero and is of moderate effect size in adulthood. However, evidence for the claim that 2D:4D reflects prenatal androgen action is limited, and the sex difference may exhibit lability during childhood. In the present study, 244 mothers were recruited in the course of an amniocentesis examination (performed between gestational weeks 14 and 18). Prenatal testosterone (T) and estradiol (E) levels were determined from amniotic fluid for boys and girls. The majority (97.4%, n = 114) of available female T levels (n = 117) were found below the level of quantification. Therefore, only male amniotic fluid data (n = 117) could be included for the analysis of associations between amniotic sex hormones (T levels and T to E ratio (T/E)) and 2D:4D. The families were then invited to each of the five consecutive follow-ups (ages: 5, 9, 20, 40, and 70 months) where children's 2D:4D was measured for both hands. The alternative marker D[r-l] reflects the directional asymmetry of 2D:4D (right subtracted by left 2D:4D) and was subsequently calculated as an additional measure for prenatal T exposure. No significant correlations between amniotic T or the T/E ratio (measured between week 14 and 18 of gestation) with 2D:4D respectively D[r-l] were observed for any time point. There was a significant sex difference (females > males) and a significant age effect with moderate correlations of 2D:4D between time points. 2D:4D increased between 20 and 40 months and between 40 and 70 months of age. The findings raise questions regarding the applicability of 2D:4D as a marker for prenatal androgen action and are discussed in terms of the reliability of obtained digit ratio data as well as in terms of the developmental timing of amniocentesis.

Second to fourth digit ratio in women with breast cancer / Relación del segundo al cuarto dígito en mujeres con cáncer de mama

SUMMARY: Digit ratio established in utero is positivelly correlated with intrauterine level of estrogen. Since the breast cancer is related to excessive and prolonged exposure to estrogen, digit ratio might be considered as useful marker in breast cancer risk assessment. The aim of the present study was to compare digit ratios in breast cancer patients and healthy controls. The study group consisted of 98 breast cancer patients aged between 29 to 84 years while the control group included 141 healthy women aged between 21 and 67 years. After collecting anamnestic data concerning menopausal status, the length of second and fourth fingers were measured and the digit ratios were calculated for both hands, as well as the difference between right and left digit ratio. Digit ratio was significantly higher on right hand in breast cancer patients compaired to healthy controls (1.003±0.05 vs. 0.990±0.03). Right digit ratio showed better predictive capacity for the breast cancer development then the left (AUC:0.609 vs. 0.541). Negative statistically significant correlation between right digit ratio and the age of breast cancer diagnosis was observed (r=-0.271). Higher values of right digit ratio in women with breast cancer when compared to healthy women suggest their higher prenatal estrogen exposure that confirms the importance of digit ratio determination in breast cancer risk assessment.

La proporción de dígitos establecida en el útero, se correlaciona positivamente con el nivel intrauterino de estrógeno. Dado que el cáncer de mama está relacionado con una exposición excesiva y prolongada a los estrógenos, la proporción de dígitos podría considerarse un marcador útil en la evaluación del riesgo de cáncer de mama. El objetivo del presente estudio fue comparar proporciones de dígitos en pacientes con cáncer de mama y controles sanos. El grupo de estudio consistió en 98 pacientes con cáncer de mama con edades comprendidas entre los 29 y los 84 años, mientras que el grupo de control incluyó a 141 mujeres sanas con edades comprendidas entre los 21 y los 67 años. Después de recopilar datos anamnésticos sobre el estado menopáusico, se midió la longitud de los dedos segundo y anular y se calcularon las proporciones de los dedos para ambas manos, así como la diferencia entre la proporción de los dedos derecho e izquierdo. La proporción de dígitos fue significativamente mayor en la mano derecha en pacientes con cáncer de mama en comparación con controles sanos (1,003 ± 0,05 frente a 0,990 ± 0,03). La proporción del dígito derecho mostró una mejor capacidad predictiva para el desarrollo de cáncer de mama que el izquierdo (AUC: 0.609 vs. 0.541). Se observó una correlación estadísticamente significativa negativa entre la proporción de dígitos derechos y la edad del diagnóstico de cáncer de mama (r=-0,271). Los valores más altos de la proporción de dígitos derechos en mujeres con cáncer de mama en comparación con mujeres sanas sugieren una mayor exposición prenatal a estrógenos que confirma la importancia de la determinación de la proporción de dígitos en la evaluación del riesgo de cáncer de mama.

No association between developmental instability as a general measure of stress and 2D:4D digit ratios in a non-western sample.

OBJECTIVE: Random deviation from perfect symmetry of organisms is defined as fluctuating asymmetry. Fluctuating asymmetry is widely considered to be a marker of developmental instability, developmental noise and phenotypic quality at the population level. In this study, we investigated hypothesized relationship between 2D:4D digit ratios as a proxy measure of prenatal sex hormones and developmental instability levels in young adult humans. MATERIALS AND METHODS: In the study, seven bilateral traits were measured for fluctuating asymmetry, as well as second and fourth digit lengths on both hands of 185 individuals, 87 men (mean age: 22.42 ± 3.37) and 97 women (mean age: 22.88 ± 3.87). The second digit length was divided by the fourth digit length and the resulting value was used as the digit ratio (2D:4D). Composite fluctuating asymmetry was calculated using five bilateral traits displaying fluctuating asymmetry. RESULTS: Only the right hand 2D:4D ratio is lower in men than in women. However, this difference disappears when the effect of digit lengths is controlled. Composite fluctuating asymmetry results reveal that men are more asymmetrical than women. There was no significant relationship between digit ratios and composite fluctuating asymmetry. CONCLUSION: In this study, the 2D:4D digit ratios appear to be influenced (at least in humans) by different digit lengths. This study also confirms previous studies that digit ratios as a proxy measure of exposure to either high testosterone or estrogen levels during early development does not appear to affect levels of developmental instability.

Digit ratio (2D:4D) and maternal testosterone-to-estradiol ratio measured in early pregnancy.

The ratio of index to ring finger (2D:4D) has been hypothesised to indicate prenatal androgen exposure, yet evidence for its validity is lacking. We report the first pre-registered study to investigate mothers' early pregnancy sex hormone concentrations in relation to their children's digit ratios measured at 18-22-month follow-up. Although the testosterone (T) to estradiol (E) ratio correlated negatively with right hand digit ratio (R2D:4D) and directional asymmetry (right-minus-left) in digit ratio (D[R-L]), neither effect remained statistically significant once demographic and obstetric covariates were controlled for. Nevertheless, the multivariate level of analysis did reveal that T correlated positively with left hand digit ratio (L2D:4D) and negatively with D[R-L]. However, the first of these effects is in the opposite direction to that predicted by theory. Taken together, the results of our study suggest research with larger samples is required to determine whether digit ratios are valid proxies for maternal sex hormone exposure.

Is there a correlation between the second to fourth digit ratio and vitiligo? A cross-sectional study.

AIMS: Vitiligo is a multifactorial, acquired skin disease of unknown etiology characterized by depigmented patches caused by melanocyte loss. The ratio of the second to fourth digits (2D:4D) is believed to be a marker of prenatal androgen exposure. Among the many hypotheses for melanocyte loss, one is that sex hormones may play a role in the development of vitiligo. In this study, we aimed to investigate a possible relationship between vitiligo and 2D:4D ratios. MATERIAL AND METHODS: The participants in this study were healthy volunteers and patients with vitiligo. This study included 100 patients with vitiligo and 110 healthy controls. An electronic Vernier caliper was employed to measure the finger lengths. The Vitiligo Extent Tensity Index was used to rate the severity of vitiligo (VETI). RESULTS: The study included 100 patients with vitiligo and 110 healthy volunteers of similar age and gender. The mean age of patients with vitiligo was 27.000 ± 13.000 years for females and 30.612 ± 9.112 years for males, and the study sample included 54 (49.09%) females and 56 (50.91%) male patients. Patients' 2D:4D ratios were significantly lower than those of the controls for right hands (p = 0.0001). For left hands, there was no correlation between the 2D:4D ratio (p = 0.740). There was no statistically significant correlation between the VETI score and the 2D/4D ratio (left hand, p = 0.136; right hand p = 0.329). CONCLUSION: To our knowledge, this is the first study to look at the link between 2D:4D ratios and vitiligo in the literature. The findings obtained in this study suggest that the 2D:4D ratio may be a predictor of vitiligo development.

Sinestre, deviance, or biology? An investigation of hand dominance in relation to tendon absence.

The present study aimed to examine the relationship between hand dominance and the presence or absence of the flexor digitorum superficialis (FDS) in the fifth digit to add to the current body of knowledge. We hypothesized that the absence of the FDS in the right small finger is more prevalent in left-handed individuals. This was a prospective study conducted from January 2020 to April 2021 and performed at the plastic surgery department of a university hospital. The sample consisted of volunteers with no history of upper limb trauma, surgery, or any other condition. The study included male and female individuals over 18 years old at a local Rhode Island university campus. The FDS tendons of the bilateral fifth fingers were evaluated through clinical testing by an independent examiner. A total of 236 hands from 118 volunteers were analyzed. Left-hand dominant participants composed of 5% of the population. For these participants, the prevalence of absence of the fifth finger FDS tendon in the right hand was significantly higher than that of right-hand dominant participants (71.4% vs. 28.8%). No significant difference between sex assigned at birth (male vs. female) was noted and the absence of the FDS in either hand, regardless of hand dominance. The results from the current study demonstrate that anatomy may contribute to one's preference for left-handedness. For children who have difficulty using their right hand, perhaps, an assessment of their FDS status may result in earlier acceptance of using their left hand.

Digit ratio (2D:4D) and body mass index in the BBC Internet Study: prenatal sex steroids and a Trivers-Willard effect on body composition.

Digit ratio - a putative measure of prenatal sex steroids - may be related to body mass index (BMI). However, reports of correlations between 2D:4D and BMI have yielded mixed results with some studies showing no relationship while others have reported positive associations in men or women only. This study considers associations between self-reported 2D:4D and BMI in a large online survey (i.e. the BBC Internet Study). At the individual level, there was a weak positive association between 2D:4D and BMI in both sexes with greater effect sizes in women. Body mass index was positively related to age and negatively related to parental income; however, the relationship between 2D:4D and BMI was independent of both variables. At the national level, mean 2D:4D per country showed positive associations with mean national BMI but those correlations were restricted to females. It is concluded that BMI is positively related to low prenatal testosterone and high prenatal oestrogen. Parental income inequality may influence both prenatal sex steroids (through a 'Trivers-Willard' effect) and BMI such that increases in inequality result in reductions in prenatal testosterone and increases in BMI at the individual and national level.

The second to fourth digit ratio (2D:4D): A risk factor of bladder cancer in men.

BACKGROUND: Exposure to prenatal sex steroids as indicated by the ratio of the second to fourth digit length (2D:4D) has been linked to the risk of onset of cancer, while sex steroids may expand the gender disparity in bladder cancer (BC) morbidity. AIM: To explore the association between 2D:4D ratio and BC risk. SUBJECTS: 307 bladder cancer patients and 321 cancer-free individuals. OUTCOME MEASURES: Relationships between 2D:4D and incidence of bladder cancer. RESULTS: For males, a lower 2D:4D ratio of both hands was obtained in the BC group, relative to the control group (left hand: 0.940 ± 0.031 vs. 0.954 ± 0.024, t = -4.72, p < 0.001, Cohen's d = 0.491 and right hand: 0.939 ± 0.031 vs. 0.952 ± 0.022, t = -4.493, p < 0.001, Cohen's d = 0.511). In females, no differences in the 2D:4D ratio were observed between the BC and control groups (p > 0.05). Correlation analysis between 2D:4D ratio and pathological index found no correlation among the BC grade or stage (p > 0.05). CONCLUSION: Men with BC have a lower 2D:4D ratio compared with healthy men. Therefore, having a low 2D:4D ratio is a risk factor for BC in men. Prenatal exposure to sex steroids might play a role in the etiology of BC, which could partially explain the gender disparity in the prevalence of BC.

Evidence for a robust, estradiol-associated sex difference in narrative-writing fluency.

Objective: Despite evidence for an estradiol-linked sex difference in verbal fluency favoring women, recent reviews question this difference. We therefore examined the issue based on a narrative task that we have administered to different populations for over 20 years. Method: We meta-analyzed 98 studies (N = 11,528) conducted by our laboratories and that featured measures of biological sex and storytelling. We ran primary-data analyses (N = 797) on an overlapping subset of these studies that also included salivary hormone and digit ratio measures. Results: Women told longer stories than men, d = 0.31, 95% CI [0.24, 0.38], an effect that did not vary by geographic region but was moderated by cue type (verbal: d = 0.57, [0.44, 0.71]; pictures: d = 0.29, [0.22, 0.36]), response modality (oral: d = -0.04, [-0.18, 0.09]; handwriting: d = 0.39, [0.31, 0.47]; typing: d = 0.31, [0.21, 0.42]), and age (prepubertal children: d = 0.13, [-0.04, 0.30]; pubescents: d = 0.48, [0.23, 0.74]; premenopausal adults: d = 0.36, [0.29, 0.42]; postmenopausal adults: d = -0.09, [-0.35, 0.16]). Consistent with the age effect, estradiol, a sex-dimorphic hormone during the reproductive life stage, was a specific mediator of the sex difference in narrative-writing fluency. This mediation effect was moderated by prenatal hormone exposure, estimated via digit ratio. Conclusions: When verbal fluency is assessed through narrative writing, a robust female advantage becomes evident. It is associated with the reproductive life stage and variations in current estradiol concentrations, particularly in individuals prenatally exposed to relatively more estradiol than testosterone. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Digit ratio (2D:4D) in women and men with lung cancer.

A prenatal sex steroid environment of high prenatal testosterone and low prenatal oestrogen inhibits lung development and may predispose individuals to be vulnerable to lung disease in later life. Therefore, the aim of this report was to investigate whether there is an association between right and left 2D:4D (biomarker of prenatal sex steroids exposure) and primary lung cancer in women and men. Also, we considered the relationship between right-left 2D:4D (Δ2D:4D, a negative correlate of high prenatal testosterone and low prenatal oestrogen) and the age of lung cancer diagnosis. The study included 109 patients (61 men) with lung cancer and 197 controls (78 men). In the study we found that: (i) women with lung cancer have lower 2D:4D compared to controls (the effect was independent of smoking), (ii) among women with cancer, age at diagnosis was positively related to 2D:4D, i.e. women with masculinized 2D:4D present earlier with the cancer than women with feminized 2D:4D, (iii) among men with lung cancer, those with the most aggressive form (small-cell lung cancer) had masculinized (low) Δ2D:4D compared to those with the less aggressive form (non-small cell lung cancer). The data suggests that masculinized right 2D:4D and Δ2D:4D are associated with a predisposition to lung cancer and/or the more aggressive forms of lung cancer.

Flexor tendon grafts for pulley reconstruction - Morphological aspects.

BACKGROUND: Pulleys are crucial to convert flexor tendon excursion into angular motion at the metacarpophalangeal and interphalangeal joints. Loss of pulley function can lead to significant impairment of hand function and may require surgical reconstruction. This reconstruction can be achieved using different flexor tendons grafts, such as the intrasynovial flexor digitorum superficialis (FDS) or the extrasynovial palmaris longus (PL). However, there is limited knowledge on the micromorphology of human pulleys and the suitability of flexor tendon grafts for their reconstruction remains elusive. METHODS: In the present cadaver study A2 and A4 pulleys were compared with FDS and PL tendons by means of scanning electron microscopy (SEM), histology and immunohistochemistry. Surface morphology, core structure and vascularization of the specimens were analyzed. RESULTS: SEM imaging of the gliding surfaces revealed morphological differences between tendons and pulleys. Moreover, the core structure of FDS samples was characterized by bundles of individual collagen fibrils whereas PL tendons exhibited a less hierarchical microstructure. In contrast, pulleys consisted of lamellar sheets of densely packed collagen fibrils. Finally, immunohistochemical analyses revealed that the flexor tendons and pulleys contain similar numbers of CD31+ microvessels, indicating a comparable tissue vascularization. CONCLUSION: This study provides novel SEM and immunohistochemical insights into the micromorphology of human pulleys and flexor tendon grafts. Intrasynovial flexor tendons may be particularly suitable for pulley reconstruction and preserving the paratenon may be crucial for graft revascularization.

Fingertip Infections.

The fingertip is the most common site of infections in the hand, which frequently are encountered by surgeons, dermatologists, and emergency and primary providers. Their mismanagement may have serious consequences. This review discusses the unique anatomy of the volar fingertip pulp and perionychium and reviews pathophysiology and treatment of acute and chronic paronychia, including the decision for surgical versus medical management, choice of antibiotics, incisional techniques, and postincisional care. Felons and the evidence regarding their management are reviewed. Several infectious, rheumatologic, and oncologic conditions that may mimic common fingertip infections and about which the managing provider must be aware are presented.

Understanding COVID-19: Digit ratio (2D:4D) and sex differences in national case fatality rates.

BACKGROUND: The reported national case fatality rates (CFRs) for coronavirus disease 2019 (COVID-19) shows a sex bias with males > females. The relative lengths of the index (2D) and ring (4D) fingers (digit ratio; 2D:4D) is a sexually dimorphic (males < females) proxy of fetal sex steroids (low 2D:4D indicates high prenatal testosterone/low prenatal estrogen). AIM: To examine sex-specific relationships of 2D:4D per nation with national values of COVID-19 CFRs. STUDY DESIGN: COVID-19 CFRs and the percent of male deaths were related to mean national (self-reported) 2D:4D by sex and hand from a large online survey (the BBC Internet Study). SUBJECTS: 103,482 men and 83,366 women. OUTCOME MEASURES: Relationships of mean national 2D:4D with CFRs from 41 countries and with national male death rates from 16 countries. RESULTS: Male right and left hand 2D:4D showed positive relationships with CFR. These relationships remained significant after removing the influence of female 2D:4D. A positive association of male right and left 2D:4D was detected with the percentage of male deaths. CONCLUSIONS: At the national level, high mean 2D:4D (indicating low prenatal testosterone/high prenatal estrogen) is associated with high CFRs and percent male mortality. At the individual level, high 2D:4D may be a risk factor for severity of COVID-19 in males. We speculate that male 2D:4D is a negative correlate for expression of the SARS-CoV2 receptor (ACE2).

The association between second to fourth digit ratio, reproductive and general health among women: findings from an Israeli pregnancy cohort.

The ratio between the length of second and fourth digits (2D:4D) is a putative biomarker for prenatal testosterone and estrogen exposure. The aim of the study was to examine the association between 2D:4D and women's general and reproductive health. This analysis was conducted within a prospective pregnancy cohort study. The study population included 187 women. 2D:4D was measured directly in both hands using a digital caliper. Multivariable linear and logistic models were used to study the associations between digit ratio and the studied health characteristics. Mean age of the participants was 30.7 ± 4.9 years. The mean age at menarche was 12.9 ± 1.4 years. Right hand 2D:4D mean ± SD was 0.965 ± 0.03. Left hand 2D:4D mean ± SD was 0.956 ± 0.03. An association was found between right 2D:4D and age at menarche, with older age in women with 2D:4D ≥ mean versus 2D:4D < mean (13.2 ± 1.5 and 12.8 ± 1.3 respectively, b = 0.48, 95%CI:0.06-0.91) while controlling for ethnicity. Higher 2D:4D was also associated with heavier menses bleeding and dysmenorrhea. There is an association between 2D:4D and sub optimal reproductive characteristics, including later age at menarche, heavier menses bleeding and dysmenorrhea. These findings support the association between the intrauterine period and reproductive characteristics. Further studies are required to support our findings.