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PubMed2002

Simultaneous toe-to-hand transfer and lower extremity amputations for severe upper and lower limb defects: the use of spare parts.

From 1995 to 2000, five microvascular toe-to-hand transfers were performed in three children who were simultaneously undergoing lower extremity amputations. Their ages at time of transfer ranged from 4 to 10 years and the types of lower extremity amputation included toe amputation, foot amputation and through-knee amputation. The resulting toe-to-hand transfers included three great toe-to-thumb transfers and one combined great and second toe-to-hand transfer. The toe-to-hand transfers were all successful and all the lower extremity amputations healed without complications. In all cases, improved hand function and lower extremity function was noted by the families. These unique cases represent the ultimate use of spare parts in congenital hand surgery.

Amputation, Surgical↗
PubMed1997

Further support for linkage of extreme obesity to the obese gene in a study group of obese children and adolescents.

The role of the obese gene in human obesity is presently unclear. Evidence for linkage of markers flanking the gene to obesity has been found in some but not all studies. We investigated transmission disequilibrium between two highly polymorphic microsatellite markers (D7S504 and D7S1875) flanking the human obese gene (OB) and extreme obesity in a study group of German children and adolescents. Due to the early onset and severity of obesity in the ob/ob mouse we hypothesized that especially children and adolescents with extreme obesity are enriched for possible mutations in the human OB. The analysis of 88 trios (index probands and both parents) for transmission disequilibrium of a haplotype which has previously been determined to be linked to extreme obesity (Reed et al., 1996) revealed a one-sided transmission disequilibrium test (TDT) p-value of 0.039. Post hoc analyses revealed one-sided TDT p-values of 0.015 for the 214 bp allele of D7S1875 (corrected p-value = 0.03) and 0.215 for the 145 bp allele of D7S504 (corrected p-value = 0.43). These findings substantiate the evidence for linkage of extreme obesity to OB.

Adolescent↗
PubMed2002

[Vascular injuries after extremity trauma].

The aim of the present examination was to analyse extremity trauma with additional vascular injuries. Between 1973-2000 78 patients with traumatic peripheral vascular injuries have been treated at the Surgical Department of the University Hospital of Mannheim. In addition to clinical examination Doppler-Duplex ultrasonography (cw-Doppler) was routinely performed. In selected cases either conventional or magnetic resonance angiography completed the diagnostic procedure. Vascular injuries to the upper extremities were found in 46.2 % (n = 36) whereas 53.8 % (n = 42) of the patients suffered from trauma of the lower extremities. The popliteal artery was affected in 28.2 % followed by the brachial artery with 23.1 %. 52.6 % of the patients had interposition of autologous vein for reconstruction. Only 7.7 % of the cases needed interposition of alloplastic material. In general the injured extremity was immobilised by external fixation, followed by secondary vascular reconstruction. An efficient trauma management reduced amputation rate as low as 2.6 %.

Adolescent↗
PubMed2005

Flow-through, functioning, free musculocutaneous flap transfer for restoration of a mangled extremity.

Reconstructing a mangled extremity requires careful, complete examination of the functional and structural status of the injured part. Although the vascular status of the injured extremity is a priority, simultaneous reconstruction of skeletal, vascular, and neuromuscular structures should be considered in a combined approach. The purpose of this study was to describe a one-stage reconstruction of both soft-tissue coverage and revascularization for a lower extremity, along with functional restoration of an anterior lower leg. For this purpose, the functioning transfer of a free latissimus dorsi musculocutaneous flap as a flow-through type was performed. The results demonstrate that the technique is extremely useful in limb-salvage procedures from both functional and structural viewpoints.

Child↗
PubMed2005

Palmar arch revascularization for arterial occlusion of the distal upper extremity.

During a period of nine years, 10 patients, ages 42 to 66 years (55 +/- 7, mean +/- SD) underwent upper extremity bypass for ischemic changes to the hand not responsive to conservative management. Patients were referred from the vascular department at the authors' institution. Preoperative angiograms were performed and attempts at angioplasty or intravenous attempts to dissolve clots were carried out (with tissue plasminogen activator-tPA) when appropriate. Patients with persistent upper extremity ischemia and an obvious occlusion with reconstitution in the hand were candidates for upper extremity bypass to the palmar arch. All patients had upper extremity bypasses performed with reverse saphenous vein grafts. The proximal anastomoses (end-to-side) were performed by either the vascular or plastic surgery team, while all distal anastomoses (end-to-side) were performed by plastic surgery team microscopic magnification to the deep or superficial palmar arch. Postoperative follow-up ranged from 3 months to 3 years. The bypass graft to the hand resulted in improved pain and resolution of tissue ischemia in all cases. Patients with preoperative ulcers were completely healed by 3 months. The results are in accordance with previous studies demonstrating that improved blood flow afforded by the procedure can improve the healing of recalcitrant ulcers and mitigate the symptoms of ischemic changes. In addition, end-to-side anastomosis to the palmar arch offers significant advantages, in that the continuity of the arch is maintained with all possible outflow vessels, and the problems associated with size discrepancy in the anastomosed vessels are eliminated.

Adult↗
PubMed1998

Reconstruction of upper-extremity peripheral-nerve injuries with ePTFE conduits.

This reported investigation was designed to determine the role of a new synthetic conduit-expanded polytetrafluoroethylene (ePTFE) tube--in clinical repair of median and ulnar nerves in the upper extremities. The main goals of this study were: to determine the effectiveness of the ePTFE conduit in clinical nerve reconstruction; to evaluate the potential of this technique in reconstruction of various nerve gaps (1.5 to 6 cm); and to analyze the results of repair with the ePTFE tube regarding different mechanisms of injury. Forty-three patients were evaluated. They had upper-extremity peripheral-nerve injuries (21 injuries to the median nerve, and 22 ulnar nerve injuries) located at the various levels of the upper extremities. All surgical procedures described in the study were secondary reconstructions, and the average delay from injury to repair was 4.2 months. With regard to the nerve-gap lengths, patients were categorized in two groups. Group 1 (gaps from 1.5 to 4 cm) included 28 patients (17 median nerve injuries and 11 ulnar nerve injuries), and Group 2 (gaps from 4.1 to 6 cm) comprised 15 patients (4 median nerve injuries and 11 ulnar nerve injuries). Results showed that 78.6 percent of patients from Group 1 demonstrated functional motor and sensory recovery, while reconstruction of only 13.3 percent of peripheral nerves from Group 2 resulted in useful reinnervation. According to published results, ePTFE conduit is a reliable and successful surgical procedure for nerve repair in reconstruction of nerve gaps up to 4 cm between the ends of median and ulnar nerves in various levels of the upper extremity. Because of its properties, ePTFE conduit has the advantages of promoting better nerve regeneration, compared to other synthetic tubes, especially in reconstruction of proximal nerve injuries, larger nerve gaps, and in cases with unfavorable mechanisms of nerve injury.

Adult↗
PubMed1991

Free groin flaps in microsurgical reconstruction of the extremity.

The authors performed free groin flap transplantation in 36 patients with extensive soft-tissue injury of the extremities. In each case, the vascular anatomy of the groin flap was analyzed during the operation. The anatomic classification of the superficial circumflex iliac artery according to its origin was as follows: a common origin with the superficial inferior epigastric artery in 15 cases (39.5 percent); an isolated origin and absent superficial inferior epigastric artery in 14 cases (36.8 percent), a separate origin in three cases (7.9 percent), and an origin from the profunda femoral artery in six cases (15.8 percent). These results are similar to those reported previously. The overall success rate was 72.2 percent. The success rate was better in the upper extremity (100.0 percent) than in the lower extremity (65.5 percent). Free vascularized groin flap transplantation is a suitable procedure for the one-stage reconstruction of severe soft-tissue injury, especially in the upper extremity.

Arm Injuries↗
PubMed2005

Natural pollution caused by the extremely acidic crater lake Kawah Ijen, East Java, Indonesia.

BACKGROUND, AIMS AND SCOPE: Lakes developing in volcano craters can become highly acidic through the influx of volcanic gases, yielding one of the chemically most extreme natural environments on earth. The Kawah Ijen crater lake in East Java (Indonesia) has a pH < 0.3. It is the source of the extremely acidic and metal-polluted river Banyupahit (45 km). The lake has a significant impact on the river ecosystem as well as on a densely populated area downstream, where agricultural fields are irrigated with water with a pH between 2.5 and 3.5. The chemistry of the river water seemed to have changed over the past decade and the negative effect in the irrigation area increased. A multidisciplinary approach was used to investigate the altered situation and to get insight in the water chemistry and the hydrological processes influencing these alterations. Moreover, a first investigation of the effects of the low pH on ecosystem health and human health was performed. METHODS: Water samples were taken at different sites along the river and in the irrigation area. Sampling for macroinvertebrates was performed at the same sites. Samples of soil and crop were taken in the irrigation area. All samples were analysed for metals (using ICP-AES) and other elements, and concentrations were compared to local and international standards. RESULTS AND DISCUSSION: The river carries a very high load of SO4, NH4, PO4, Cl, F, Fe, Cu, Pb, Zn, Al and other potentially toxic elements. Precipitation and discharge data over the period of 1980-2000 clearly show that the precipitation on the Ijen plateau influences water chemistry of the downstream river. Metal concentrations in the river water exceed the concentrations mentioned in Indonesian and international quality guidelines, even in the downstream river and the irrigation area. Some metal concentrations are extremely high, especially iron (up to 1,600 mg/l) and aluminium (up to 3,000 mg/l). The food-webs in the acidic parts of the river are highly underdeveloped. No invertebrates were present in the extremely acidic water and, at pH 2.3, only chironomids were found. This also holds true for the river water with pH 3.3 in the downstream area. Agricultural soils in the irrigation area have a pH of 3.9 compared to a pH of 7.0 for soils irrigated with neutral water. Decreased yields of cultivated crops are probably caused by the use of Al containing acidic irrigation water. Increased levels of metals (especially Cd, Co, Ni and Mn) are found in different foodstuffs, but still remain within acceptable ranges. Considering local residents' diets, Cd levels may lead to an increased risk for the human health. Fluoride exposure is of highest concern, with levels in drinking water exceeding guideline values and a lot of local residents suffering from dental fluorosis. CONCLUSIONS, RECOMMENDATIONS AND OUTLOOK: In short, our data indicate that the Ijen crater lake presents a serious threat to the environment as well as human health and agricultural production.

Animals↗
PubMed2000

An evaluation of botulinum-A toxin injections to improve upper extremity function in children with hemiplegic cerebral palsy.

OBJECTIVE: In a randomized, controlled, single-blind trial, to test the hypothesis that botulinum-A toxin (BTA) injections into the upper extremity of children with spastic hemiplegia improve upper extremity function. STUDY DESIGN: Thirty children with hemiplegia, aged 2.5 to 10 years, were randomly assigned to receive: (1) a BTA injection into 1 or more of 3 muscle groups (biceps, volar forearm muscles, adductor pollicis) plus occupational therapy or (2) occupational therapy alone. Blinded outcomes obtained at baseline and at 1, 3, and 6 months included the Quality of Upper Extremity Skills Test (QUEST), goniometry measurements, grip strength, and Ashworth scores. The caregiver completed the self-care domain of the Pediatric Evaluation of Disability Inventory. RESULTS: Twenty-nine subjects completed the study. The QUEST demonstrated a significant improvement favoring the treatment group on a 2-way analysis of variance (F = 4.69, df = 1,83; P =.039). BTA treatment was also associated with an improvement in score on the self-care domain of the Pediatric Evaluation of Disability Inventory (F = 4.68, df = 1,82; P =.04). CONCLUSIONS: This study supports the effectiveness of BTA injections to improve upper extremity function of children with hemiplegia who have at least moderate spasticity.

Analysis of Variance↗
PubMed1989

Does open fasciotomy contribute to morbidity and mortality after acute lower extremity ischemia and revascularization?

A retrospective review was undertaken of 127 lower extremity fasciotomies performed for compartment syndrome after acute ischemia and revascularization in 73 patients with vascular trauma and 49 patients with arterial occlusive disease. One hundred twelve (88%) fasciotomies were performed early (at the time revascularization); 15 (12%) were delayed because of late compartment syndrome diagnosis. Ninety-four (77%) patients had more than one accepted indication for fasciotomy. Double-incision fasciotomy was used in 98 (77%) extremities, single-incision fasciotomy was used in 19 (15%), and fasciotomy-fibulectomy was used in 10 (8%). Fasciotomies were closed in 88 (69%) patients an average of 14 days after surgery. Seven patients needed multiple skin grafting procedures or myocutaneous flaps to close the wound; none compromised limb salvage. Five other patients had minor wound infections that resolved. Functional status returned to preoperative levels by the time of discharge from the hospital in 59 (48%) patients. Thirty-one (24%) patients had residual lower extremity disability related to delayed union of the fracture (five), chronic neuropathy (20), leg swelling (one), or ischemic nonhealing fasciotomy wounds (three); two patients had unrelated disabilities. Fourteen (11%) amputations were required for refractory limb ischemia; two (1.6%) were required for wet gangrene of the foot, which infected the fasciotomy site; the others had open noninfected incisions. Eighteen (15%) patients died of cardiopulmonary failure or multisystem failure or both, without fasciotomy-related problems. Open fasciotomy for compartment syndrome after acute lower extremity ischemia and revascularization was associated with an increased risk of minor wound morbidity. However, limb loss and death resulted from persistent ischemia and underlying systemic disease processes or injuries, but not from open fasciotomy wound complications.

Adolescent↗
PubMed2000

Arm vein conduit is superior to composite prosthetic-autogenous grafts in lower extremity revascularization.

PURPOSE: Various alternative conduits have been used for lower extremity revascularization when an adequate ipsilateral greater saphenous vein is absent. This study compared the effectiveness of all-autogenous multisegment arm vein bypass grafts with that of composite grafts composed of combined prosthetic and autogenous conduits. METHODS: One hundred fifty-three lower extremity revascularization procedures performed between 1990 and 1998 were followed up prospectively using a computerized vascular registry. The grafts were composed of spliced arm vein segments with venovenostomy in 122 and of composite prosthetic-autogenous conduit in 31. Arm vein conduit was prepared by means of intraoperative angioscopy for valve lysis and identification of luminal abnormalities in 47.7% of cases. RESULTS: Bypass graft configurations were as follows: femoropopliteal (12 arm vein, 2 composite); femorotibial (75 arm vein, 23 composite); femoropedal (14 arm vein, 6 composite), and popliteo-tibial/pedal (21 arm vein, 0 composite). The indication for surgery was limb salvage in 98% and disabling claudication in 2% of cases. The mean follow-up was 25.1 months (range, 1 month to 7.9 years). Overall survival at 4 years was 51%. Overall patency and limb salvage rates were as follows: primary patency, at 1 year-arm vein, 76.9% +/- 4.8%; composite, 59. 5% +/- 9.6% (P =.02); at 3 years-arm vein, 70.0% +/- 8.0%; composite, 43.7% +/- 12.4% (P <.01); and at 5 years-arm vein, 53.8% +/- 8.7%; composite, 0%; secondary patency, at 1 year-arm vein, 77.5% +/- 4. 6%; composite, 59.8% +/- 9.5% (P =.02); at 3 years-arm vein, 70.7% +/- 7.5%, composite, 44.9% +/- 13.1% (P <.01); at 5 years-arm vein, 57.7% +/- 8.0%; composite, 0%; limb salvage, at 1 year-arm vein, 89. 3% +/- 3.7%; composite, 73.9% +/- 8.9% (P <.01); at 3 years-arm vein, 80.5% +/- 7.0%; composite, 49.6% +/- 14.3% (P <.01); at 5 years-arm vein, 76.3% +/- 9.9%; composite, 0%. CONCLUSION: In this study, multisegment autogenous arm vein was used successfully in a wide variety of lower extremity revascularization procedures and achieved good long-term patency and limb salvage rates, well in excess of those achieved with composite prosthetic-autogenous grafts. The use of autogenous conduit appears to offer superior results to composite conduit in lower extremity revascularization. The superior durability of arm vein makes it one of the alternative conduits of choice when an adequate greater saphenous vein is not available.

Aged↗
PubMed2001

Efficacy and durability of autogenous saphenous vein conduits for lower extremity arterial reconstructions in preadolescent children.

OBJECTIVE: Limb length discrepancies (LLDs) in growing children may accompany extremity arterial occlusions. Revascularization with vein grafts has been questioned because of degenerative graft changes observed at other sites. This study was undertaken to define vein graft durability and efficacy in lower extremity revascularizations in preadolescent children. STUDY DESIGN: Fourteen children (10 boys, 4 girls) with a mean age of 7.3 years (range, 2-11 years) who underwent 16 lower extremity revascularizations with greater saphenous vein grafts were subjected to follow-up with graft ultrasonography, ankle/brachial indices (ABIs) with and without exercise, and limb length determinations. A mean of 5.7 years elapsed between the onset of ischemia and operation. Arterial occlusions resulted from cardiac catheterizations (11), arteritis (1), dialysis cannulation (1), and penetrating trauma (1). Indications for operation included LLD (6), claudication (4), both LLD and claudication (3), markedly diminished ABIs with a potential for LLD (2), and a traumatic transection with hemorrhage (1). The reconstructions with 15 reversed and one in situ vein grafts included iliofemoral (11), femorofemoral (1), aortofemoral (1), femoropopliteal (1), popliteal-popliteal (1), and popliteal-posterior tibial (1) arterial bypass grafts. RESULTS: Among patent grafts available for follow-up, 36% (5 of 14) remained unchanged, 50% (7 of 14) developed nonaneurysmal dilatation, and 14% (2 of 14) exhibited nonprogressive aneurysmal expansion. One graft became occluded, and one graft was lost to follow-up. Collectively, the grafts manifest an 11.2% expansion at an average of 10.7 years postoperatively. ABIs increased from 0.75 preoperatively to 0.97, at an average of 11.0 years postoperatively. LLDs were reduced from 1.66 to 1.24 cm, at an average of 11.4 years postoperatively. CONCLUSION: Vein graft reconstructions of lower extremity arteries in preadolescent children are durable. They provide an efficacious means of restoring normal blood flow, and in 70% of children their preexisting LLDs were reduced.

Angiography, Digital Subtraction↗
PubMed2002

A quantitative approach to lower extremity vein repair.

OBJECTIVE: We prospectively investigated the patency of venous repair in a quantitative fashion with measurement of vein blood flow velocities after lower extremity injuries caused by either military or civilian trauma. MATERIAL AND METHODS: During a 10-year study period (March 1990 to December 2000), surgical intervention was performed after lower extremity vascular injuries in 130 patients. Most of these patients were men (n = 125), with a mean age of 23 +/- 5 years (range, 17 to 44 years). One hundred ten direct venous injuries were identified in 97 patients, involving the common femoral vein in seven, the deep femoral vein in three, the superficial femoral vein in nine, the popliteal vein in 46, and the posterior tibial (n = 21), anterior tibial (n = 17), or peroneal veins (n = 7) in 45. Popliteal vein thrombosis without apparent venous injury was found in seven patients. Bone fractures (n = 45), nerve injuries (n = 27), or extensive tissue loss (n = 7) often were associated with vascular injuries. Duplex color ultrasonography was used to evaluate patency and to measure blood flow velocity in repaired veins during the early postoperative period and at the time of late follow-up examinations. RESULTS: Significant differences were seen in venous blood flow velocities between severe (extremity diameter more than twice normal) and moderate (diameter 1.5 to 2 times normal) reperfusion injuries. The mean flow velocity in repaired popliteal veins was 15 +/- 2 cm/s with severe reperfusion injuries compared with 8.4 +/- 1.1 cm/s with moderate reperfusion injuries (P <.0001). Flow velocities were lower than 5 cm/s in repaired infrapopliteal veins, and most of these veins occluded on the first postoperative day. Amputations were necessary in 11 patients, all of whom had both tibial fractures and extensive tissue loss. Sodium warfarin therapy was routinely administrated before hospital discharge. The mean follow-up period was 6.2 years (range, 1.3 to 10 years). Repaired common femoral and superficial femoral veins had relatively high patency rates (100% and 89% at 1 year, 100% and 78% at 6 years, respectively), whereas the patency rates for repaired popliteal veins were disappointing (86% at 1 year, 60% at 6 years). All seven popliteal veins that required thrombectomy in the absence of direct injuries remained patent, however. Patch angioplasty had the highest 6-year patency rate (75%) in comparison with all other techniques that were used for venous injuries (lateral repair, 58%; end-to-end anastomosis, 43%; saphenous vein graft interposition, 36%). CONCLUSION: Venous repair has a high patency rate at the femoral and popliteal levels, but the patency rate for infrapopliteal venous repair is extremely poor because of low flow velocities. Therefore, we conclude that repair of infrapopliteal venous injuries is unnecessary.

Adolescent↗
PubMed2003

Does subintimal angioplasty have a role in the treatment of severe lower extremity ischemia?

OBJECTIVE: Subintimal angioplasty (SIA) has been advocated to treat long segment lower extremity arterial occlusions, but many question its value. We evaluated the role of SIA in a group of patients with severe lower extremity arterial occlusive disease. METHODS: During a 2.5-year period, 39 patients with arterial occlusions (median length, 8 cm; range, 2 to 31 cm) were treated on an intention-to-treat basis with SIA. Twenty-five patients had gangrene, five had rest pain, and nine had disabling (<one block) claudication. There were 24 superficial femoral, two superficial-femoral-popliteal, four popliteal, two popliteal-tibial, five tibial, and two external iliac artery lesions. With fluoroscopic guidance, via a prograde common femoral artery puncture (n = 29) or a contralateral common femoral artery puncture (n = 9), a subintimal dissection plane was created across the occlusion with a standard guidewire and catheter. The arterial lumen was reentered distal to the occlusion, and the recanalized segment balloon was dilated. All patients were followed prospectively with arterial duplex scan. RESULTS: SIA was technically successful in 34 of 39 patients (87%). All five failures were from an inability to reenter the patent lumen distally. These five patients underwent successful bypasses that in no case were more distal than would have been required before SIA. In the 34 technically successful SIAs, pain completely resolved (14/14) and areas of gangrene (21/25) healed. The cumulative patency rate in patients who underwent successful SIA was 74% +/- 10% at 12 months. The mean increase in ankle-brachial index after SIA was 0.34 (range, 0.1 to 0.69). There were two distal embolic events, successfully treated surgically (n = 1) or with catheter-directed techniques (n = 1). Three patients underwent subsequent bypass, and the remaining five patients remain asymptomatic. CONCLUSION: SIA is feasible and can be effective in some patients with lower extremity arterial occlusions and threatened limbs. These results, plus SIA's many advantages, support an increasing role for it in the treatment of lower extremity arterial occlusive disease.

Aged↗
PubMed2003

Does labor influence neonatal and neurodevelopmental outcomes of extremely-low-birth-weight infants who are born by cesarean delivery?

OBJECTIVE: The purpose of this study was to examine the influence of labor on extremely-low-birth-weight infants who were born by cesarean delivery with reference to neonatal and neurodevelopmental outcomes. We hypothesized that infants who are born by cesarean delivery without labor will have better outcomes than those infants who are born by cesarean delivery with labor. STUDY DESIGN: This was a retrospective cohort study of extremely-low-birth-weight infants (birth weight, 401-1000 g) who were born by cesarean delivery and cared for in the National Institute for Child Health and Human Development Neonatal Network, during calendar years 1995 to 1997. A total of 1606 extremely-low-birth-weight infants were born by cesarean delivery and survived to discharge. Of these, 1273 infants (80.8%) were examined in the network follow-up clinics at 18 to 22 months of corrected age and had a complete data set (667 infants were born without labor, 606 infants were born with labor). Outcome variables that were examined include intraventricular hemorrhage grade 3 to 4, periventricular leukomalacia, and neurodevelopmental impairment. RESULTS: Mothers in the cesarean delivery without labor group were older (P<.001), more likely to be married (P<.05), less likely to be supported by Medicaid (P<.01), more likely to have preeclampsia/hypertension (P<.001), more likely to receive prenatal steroids (P<.005), and less likely to have received antibiotics (P<.001). Infants who were born by cesarean delivery without labor had higher gestational age (P<.001), lower birth weight (P<.01), and were less likely to be outborn (P<.001). By univariate analysis, infants who were born by cesarean delivery with labor had a higher incidence of grade 3 to 4 intraventricular hemorrhage (23.3% vs 12.1%, P<.001), periventricular leukomalacia (8.5% vs 4.7%, P<.02), and neurodevelopmental impairment (41.7% vs 34.6%, P<.02). Logistic regression analysis that controlled for all maternal and neonatal demographic and clinical variables that were statistically associated with labor or no labor revealed that the significant differences in grade 3 to 4 intraventricular hemorrhage, periventricular leukomalacia, and neurodevelopmental impairment were no longer evident. CONCLUSION: In extremely-low-birth-weight infants who were born by cesarean delivery and after control for other risk factors, labor does not appear to play a significant role in adverse neonatal outcomes and neurodevelopmental impairment at 18 to 22 months of corrected age.

Adult↗
PubMed2006

Extreme heat reduces and shifts United States premium wine production in the 21st century.

Premium wine production is limited to regions climatically conducive to growing grapes with balanced composition and varietal typicity. Three central climatic conditions are required: (i) adequate heat accumulation; (ii) low risk of severe frost damage; and (iii) the absence of extreme heat. Although wine production is possible in an extensive climatic range, the highest-quality wines require a delicate balance among these three conditions. Although historical and projected average temperature changes are known to influence global wine quality, the potential future response of wine-producing regions to spatially heterogeneous changes in extreme events is largely unknown. Here, by using a high-resolution regional climate model forced by the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios A2 greenhouse gas emission scenario, we estimate that potential premium winegrape production area in the conterminous United States could decline by up to 81% by the late 21st century. While increases in heat accumulation will shift wine production to warmer climate varieties and/or lower-quality wines, and frost constraints will be reduced, increases in the frequency of extreme hot days (>35 degrees C) in the growing season are projected to eliminate winegrape production in many areas of the United States. Furthermore, grape and wine production will likely be restricted to a narrow West Coast region and the Northwest and Northeast, areas currently facing challenges related to excess moisture. Our results not only imply large changes for the premium wine industry, but also highlight the importance of incorporating fine-scale processes and extreme events in climate-change impact studies.

Agriculture↗
PubMed1976

Conjugate points on a limiting extremal.

Theorem 1, together with the author's extensions of the Sturmian Comparison Theorems, will suffice to establish the basic Theorem 27.3, p. 211 of Global Variational Analysis: Weierstrass Integrals on a Riemannian Manifold. Mathematical Notes, Princeton University Press, Princeton, N.J., 1976. Here and in the preceding reference there is given a Weierstrass Integral on a compact, connected, Riemannian manifold M(n), conditioned as in the above reference. Let gamma be an arbitrary extremal of J joining a point P to a point Q, not equal P on M(n). An extremal zeta of J joining A to B is termed nondegenerate if A and B are not conjugate on zeta. The index of zeta is by definition the "count" of conjugate points of A on zeta definitely preceding B.THEOREM 1. When the extremal gamma is nondegenerate, extremals of J issuing from P with the same length as gamma and sufficiently near gamma in the sense of Fréchet, are nondegenerate and have the same index as gamma.

Journal Article↗
PubMed1991

Work under extreme conditions.

Extreme conditions are defined in terms of deviation from the norm, and the mismatch between capacity and demand. Analysis of ergonomic job description data revealed the predominance, through their frequent occurrence, of extreme conditions. Extreme work environment conditions, such as climate, acceleration, and air pressure, are discussed. Task and error-concepts for workers operating under extreme workload are investigated, with reference to Chernobyl, stress-strain concepts for ATC, college examinations and shiphandling.

Acceleration↗