Use of blood flow restriction for increasing the strength of the ischiocrural muscles in anterior cruciate ligament rehabilitation: A case report

BACKGROUND

The hamstring muscles have a key function in the stability of the knee, limiting the anterior translation of the tibia. Therefore, to better perform rehabilitation after anterior cruciate ligament (ACL) surgery, it is important to develop a specific program based on hamstring strength recovery. It is possible to increase strength and muscle hypertrophy through high load exercises (HL); the recommended load is about 60%-80% of a maximum repetition (MR). Although low-load resistance training (LL) is ineffective at reproducing these values, the use of Blood Flow Restriction (BFR) with LL exercises appears to allow athletes to increase strength and muscle hypertrophy. This could limit functional decline and mitigate muscle atrophy allowing to optimize the recovery path and load management in post-operative patients. Recent scientific evidence, as far as the increasingly frequent use of BFR in rehabilitation and sports rehabilitation is concerned, suggests that these devices could represent one of the most significant innovations in the physiotherapy field. The aim of this study was to increase the strength of the hamstrings in the early phases of ACL rehabilitation with an LL-BFR training protocol for speeding up the development of adequate muscle strength.

CASE DESCRIPTIONS

The patient, a 25-year-old male professional footballer, suffered from ACL injury during a football match, and after three months, he underwent a reconstruction ACL surgery with medial Hamstring tendon autograft. The athlete engaged a pre-operative program to restore a full active and passive knee range of motion and increase muscular strength. The first rehabilitation phase was supported by the adoption of BFR for hamstring strengthening, starting from the sixth week post-surgery (T0). A complete assessment of posterior hamstring muscles was performed through a hand-held dynamometer and load detection platforms. Three different types of exercises, focusing on the hamstring muscles, were chosen. Two further assessments were performed over time (T1 ant T2), highlighting different changes that occurred.

RESULTS

Interesting results showed a significant increase between T0 and T1 for all the assessed outcomes; in this case an average increase in strength of 59.87% between the beginning and the end of 4 weeks rehabilitation protocol was obtained in the first interval (T0-T1), while only 25.26% resulted in the second interval (T1-T2). However, the collected data should be considered with caution due to some limitations: the single experience of a single patient can hardly be generalized. Moreover, the reliance on isometric measurement of maximal strength and the absence of a direct strength measurement of the hamstrings during squat remain questionable.

CONCLUSION

The final results suggest the capacity of the LL-BFR exercises to recreate a condition of a high intensity muscular effort with respect to load management, especially after surgery. This highlights the need to further investigate BFR adoption as it allows the patients to speed up their rehabilitation goals in developing adequate muscle strength.

Rehabilitation following shoulder arthroplasty: a survey of current clinical practice patterns of Italian physiotherapists

BACKGROUND

The incidence of Total Shoulder Arthroplasty (TSA) and Reverse Total Shoulder Arthroplasty (RTSA) is constantly increasing. As a result, the interest in post-surgical rehabilitation has grown, since it is crucial in order to achieve full recovery and successful outcomes. The first aim of this study is to investigate the Italian physiotherapists (PTs) clinical practice in the management of patients with TSA and RTSA and to compare it with the best evidence available in the literature. The second purpose of this study is to assess any existing difference between the survey answers and the different sample subgroups.

MATERIALS AND METHODS

This cross-sectional observation study was designed following the CHERRIES checklist and the STROBE guidelines. A 4-sections survey with a total of 30 questions was developed for investigating post-surgery rehabilitation management in patient with TSA and RTSA. The survey was sent to Italian PTs from December 2020 until February 2021.

RESULTS

Six-hundred and seven PTs completed the survey regarding both TSA and RTSA; 43.5% of participants (n = 264/607) stated that TSA is more likely to dislocate during abduction and external rotation. Regarding reverse prosthesis, 53.5% (n = 325/607) affirmed RTSA is more likely to dislocate during internal rotation, adduction and extension. In order to recover passive Range of Motion (pROM), 62.1% (n = 377/607) of participants reported that they gain anterior flexion, abduction, internal rotation, external rotation up to 30°, with full pROM in all directions granted at 6-12 weeks. Regarding the active ROM (aROM), 44.2% (n = 268/607) of participants stated that they use active-assisted procedures within a range under 90° of elevation and abduction at 3-4 weeks and higher than 90° at 6-12 weeks, with full recovery at a 3-month mark. Sixty-five point seven percent of the sample (n = 399/607) declared that, during the rehabilitation of patients with TSA, they tend to focus on strengthening the scapular and rotator cuff muscles, deltoid, biceps and triceps. Conversely, 68.0% (n = 413/607) of participants stated that, for the rehabilitation of patients with RTSA, they preferably focus on strengthening the periscapular and deltoid muscles. Finally, 33.1% (n = 201/607) of participants indicated the instability of the glenoid prosthetic component as the most frequent complication in patients with TSA, while 42.5% (n = 258/607) of PTs identified scapular neck erosion as the most frequent post-RTSA surgery complication.

CONCLUSIONS

The clinical practice of Italian PTs effectively reflects the indications of the literature as far as the strengthening of the main muscle groups and the prevention of movements, which may result in a dislocation, are concerned. Some differences emerged in the clinical practice of Italian PTs, regarding the restoration of active and passive movement, the starting and progression of muscle strengthening and the return to sport (RTS). These differences are actually quite representative of the current knowledge in post-surgical rehabilitation for shoulder prosthesis in the rehabilitation field.

LEVEL OF EVIDENCE

V.

Parsonage-Turner Syndrome mimicking musculoskeletal shoulder pain: A case report during the SARS-CoV-2 pandemic era

Parsonage-Turner Syndrome or neuralgic amyotrophy is a peripheral neuropathy typically characterized by an abrupt onset of pain, followed by progressive neurological deficits (e.g. weakness, atrophy, occasionally sensory abnormalities) that involve the upper limb, mainly the shoulder, encompassing an extensive spectrum of clinical manifestations, somehow difficult to recognize. This case report describes the proper management of a 35-year-old, bank employee and sports amateur who reported subtle and progressive upper limb disorder with previous history of neck pain. SARS-CoV-2 pandemic era made patient's access to the healthcare system more complicated. Nevertheless, proper management of knowledge, relevant aspects of telerehabilitation-based consultation for musculoskeletal pain, advanced skills, tools and technologies led the physiotherapist to suspect an atypical presentation of Parsonage-Turner Syndrome. Further, neurologist consultation and electromyography suggested signs of denervation in the serratus anterior and supraspinatus muscle. Therefore, an appropriate physiotherapist's screening for referral is conducted to correct diagnosis and thorough treatment.

Intracranial Epidermoid Cyst Mimics Musculoskeletal Shoulder Disease: Findings from a Case Report in Physiotherapy Clinical Practice

Shoulder pain is often attributable to a musculoskeletal disorder, but in some instances, it may be linked to pathologies outside the physiotherapist's area of expertise. Specifically, some intracranial problems can cause pain and disability to the shoulder complex. This case report aims to describe the clinical presentation, history taking, physical examination, and clinical decision-making procedures in a patient with an intracranial epidermoid cyst mimicking a musculoskeletal disorder of the shoulder girdle. A 42-year-old man complained of pain and disability in his left shoulder. Sudden, sharp pain was reported during overhead movements, associated with intermittent tingling of the left upper trapezius and left scapular area. Moreover, the patient reported reduced hearing in his left ear and left facial dysesthesia. The physical examination led the physiotherapist to hypothesize a pathology outside the physiotherapist's scope of practice and to refer the patient to another health professional to further investigate the patient through imaging. It is essential for the physiotherapist to recognize when the patient's clinical condition requires a referral to another healthcare professional. Therefore, the physiotherapist must be able to, in a timely manner, identify signs and symptoms suggesting the presence of medical pathology beyond his expertise, through appropriate medical history collection and physical evaluation.

Identifying peripheral arterial diseases or flow limitations of the lower limb: Important aspects for cardiovascular screening for referral in physiotherapy

Many conditions could potentially cause pain in the lower limbs. One of these is peripheral arterial disease (PAD). PAD is often a real challenge to be recognized for clinicians due to symptoms that commonly mimic musculoskeletal conditions. PAD is defined as a total or partial blockage of the vessels that supply blood from the heart to the periphery. Its prevalence is around 7 percent in subjects between 55 and 59, reaching almost 25% in individuals between 95 and 99 years old. The most dominant symptom of PAD is lower limb pain. Also, PAD can produce other symptoms such as discoloration, altered skin temperature, and, when arterial blood flow is insufficient to meet the metabolic demands of resting muscle or tissue, focal areas of ischemia. In our view, physical therapists should be capable of triaging for PAD in a direct access setting. Therefore, in this Professional Issue, we present the main characteristics of PAD and the physiotherapy role in its management. A supplementary step-by-step guide will provide further resources for testing PAD.

Manipulation under Anesthesia versus Non-Surgical Treatment for Patients with Frozen Shoulder Contracture Syndrome: A Systematic Review

Purpose: To investigate the efficacy of manipulation under anesthesia (MUA) compared to other non-surgical therapeutic strategies for patients with frozen shoulder contracture syndrome (FSCS). Methods: A systematic review of literature was conducted. A literature search was performed in MEDLINE, EMBASE, PEDro, Cochrane Central Library and Scopus. Only randomized controlled trials were included and assessed for critical appraisal through the Cochrane Collaborations tools. Results: Five randomized controlled trials were included. The overall risk of bias (RoB) was high in 4 out of 5 of the included studies. MUA was found to be not superior in terms of reduction of pain and improvement of function when compared to cortisone injections with hydrodilatation (mean regression coefficient MUA −2.77 vs. injection −2.75; 95% CI (−1.11 to 1.15)) and home exercise (mean difference 95% CI: 0.2 (−0.64 to 1.02)) in the short term (3 months), and cortisone injections with hydrodilatation (mean regression coefficient MUA 3.13 vs. injection 3.23; 95% CI (−0.90 to 1.11)) in the long term (>6 months). Moreover, if compared to structured physiotherapy, MUA highlighted a higher Oxford Shoulder Score at final 1-year follow up (mean difference 95% CI: 1.05 (−1.28 to 3.39); p = 0.38). Similar results were obtained for disability, with statistically no significant long-term (>12 months) differences between MUA and home exercise (mean difference 95% CI: 0 (−3.2 to 3.2)) or structured physiotherapy (mean difference 95% CI: −0.50 (−5.70 to 4.70); p = 0.85)). Only two trials reported adverse events. Conclusions: This review suggested that limited and inconsistent evidence currently exists on the efficacy of MUA compared to other non-surgical strategies in the management of patients with FSCS. Future research should focus on clinical trials with higher methodological quality.

Osteoid Osteoma in an Adult Wheelchair Basketball Player Mimicking Musculoskeletal Shoulder Pain: Red Flag or a Red Herring?

Osteoid osteoma (OO) is a relatively common, benign bone-forming tumour, which mainly occurs on the long tubular bones of the limbs in adolescents. Usually, the OO is classified based on its localisation. Night-time pain is the major symptom of OO, which is commonly relieved using non-steroidal anti-inflammatory drugs, while surgery is required only for those patients with severe pain or in case of failure of previous conservative treatments. Our case report describes a 56-year-old male basketball player who self-referred to our outpatient physical therapy with a shoulder pain complaint. Considering the anamnesis and the physical examination, the physical therapist referred the patient to an orthopaedic surgeon, who suggested a detailed imaging investigation. The peculiarity of this clinical case is the overlapping of two clinical presentations: the symptomatology of the OO and the concurrent mechanical disorder due to a rotator cuff tendinopathy.

Rotator cuff repair vs. nonoperative treatment: a systematic review with meta-analysis

BACKGROUND

Rotator cuff (RC) tears have been widely studied as many treatment strategies have been recommended. However, optimal management for patients with RC tears is still unclear.

PURPOSE

The main aim of this systematic review was to analyze randomized controlled trials using meta-analysis to compare repair to conservative treatments for patients with any type of RC tear.

METHODS

MEDLINE, Cochrane Library (CENTRAL database), PEDro, and Scopus databases were used. Two independent reviewers selected randomized controlled trials that compared surgical to conservative treatments for RC tear patients. The studies included were assessed using Cochrane Risk of Bias 2 tools, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used to evaluate the certainty of evidence and to summarize the study conclusions.

RESULTS

Six trials were included. Pooled results showed improvement in function and pain perception in favor of the repair group at 6 months (mean difference 1.26, 95% CI -2.34, 4.85, P = .49; and -0.59, 95% CI -0.84, -0.33, P < .001, respectively), at 12 months (mean difference 5.25, 95% CI 1.55, 8.95, P = .005, for function; and -0.41, 95% CI -0.70, -0.12, P = .006, for pain) and at 24 months (mean difference 5.57, 95% CI 1.86, 9.29, P = .003, for function; and -0.92, 95% CI -1.31, -0.52, P < .001, for pain) in RC tear patients. However, these differences did not reach the minimum clinically important difference. The certainty of evidence ranged from low to moderate because of imprecision in the studies included.

CONCLUSIONS

Overall analysis showed that in patients with RC tear, repair compared with conservative treatment could result in increased pain reduction and functional improvement at 6, 12, and 24 months. Even if these effects were often statistically significant, their clinical relevance was limited. Moreover, the certainty of body of evidence ranged from low to moderate.

Assessing Cranial Nerves in Physical Therapy Practice: Findings from a Cross-Sectional Survey and Implication for Clinical Practice

BACKGROUND AND OBJECTIVE

Serious pathologies of the neck can potentially result in cranial nerve palsy. Knowledge about cranial nerve examination (CNE) seems sparse, and its use is still unknown. We aim to investigate the knowledge, skills, and utilization of CNE of Italian physiotherapists.

MATERIALS AND METHODS

An online cross-sectional survey.

RESULTS

396 completed the survey, reaching the required sample size. Although Italian physiotherapists consider CNE relevant (mean ± SD = 7.6/10 ± 2.0), over half of all responders (n = 229 (57.8%)) were not trained in the fundamentals and around a third did not use it in their daily practice (n = 138 (34.8%)). Additionally, participants were unconfident and insecure in conducting (n = 152 (38.4%) and n = 147 (37.1%)), interpreting (n = 140 (35.4%) and n = 164 (41.4%)), and managing the CNE (n = 141 (35.6%) and n = 154 (38.9%)). Possessing a musculoskeletal specialization was associated with an increased value attributed to clinical practice guidelines and reduced the lack of confidence in conducting, interpreting, and managing the CNE (respectively, n = 35 (25.5%), p = 0.0001; n = 32 (23.4%) p = 0.0002; n = 32 (23.4%) p = 0.0002). Working in a direct access setting significantly increased the considered relevance of guidelines and the concerns about arterial (p = 0.004) and other serious pathologies (p = 0.021). Pain and visual disturbances were considered the main indicators to CNE, demonstrating limited knowledge of signs and symptoms' indicating CNE. Participants considered specific training in CNE as relevant (mean ± SD = 7.6/10 = 2.1).

CONCLUSIONS

a substantial proportion of Italian physiotherapists are not schooled in the fundamentals of cranial nerve examination. Given the number of physiotherapists who work in first contact roles, this is a professional concern.

A Thoracic Outlet Syndrome That Concealed a Glioblastoma. Findings from a Case Report

Background: Glioblastoma is the most frequent and aggressive malignant brain tumor among adults. Unfortunately, its symptoms can vary considerably depending on the size, location and the anatomic structures of the involved brain. Case report: A 58-year-old male amateur cyclist who suffered from sharp arm pain was examined for a thoracic outlet syndrome due to a previous clavicle fracture. Because of ambiguous results of the neck and nerve plexus imaging, he was referred to a neurosurgeon who properly suspected a brain tumor. The neuroimaging of the brain shown a 3 cm disploriferative mass with a blood enhancement within the left parietal lobe. The mass was urgently removed, and its histologic analysis stated a grade 4 glioblastoma. Conclusion: This case report highlights the differential diagnosis process and the teamwork approach needed to diagnose a rare presentation of a brain glioblastoma, which started its symptoms mimicking a thoracic outlet syndrome caused by a previous bone fracture.

Can Haglund's Syndrome Be Misdiagnosed as Low Back Pain? Findings from a Case Report in Physical Therapy Direct Access

Background: Haglund’s syndrome (HS) is a painful condition that is caused by an exostosis of the posterior superior part of the calcaneus coupled with Achilles tendinopathy and retrocalcaneal bursitis. Both for the proper musculoskeletal assessment and for the differential diagnosis process of possible concurrent diseases deriving from other anatomical areas, the diagnosis of HS is still a challenge. Case Presentation: A 41-year-old male amateur runner was diagnosed and treated for low back pain and referred leg pain by his general practitioner. Due to ineffective results, he self-presented to a physical therapist (PT) with intense right heel pain, radiating up to the leg and to the lumbopelvic region. Results: The PT’s examination and interview relating to the sports activities led to the correct diagnosis and a proper orthopedic referral. At the one-year follow-up, the patient reported regular pain-free marathon running. Discussion: This case report highlights the central role of PTs working in direct access environments as primary care healthcare professionals for the management of musculoskeletal diseases, and their abilities in identifying patients with suspected pathologic conditions that may need referral for imaging, medical assessment or surgical intervention.

A Rare Consequence after Shoulder Dislocation in a Professional Cyclist: A Case Report

Background: Cycling is a popular source of recreation and physical activity for children and adults. With regard to the total number of sports injuries, cycling has the highest absolute number of injuries per year in the United States population. Cycling injuries can be classified into bicycle contact, traumatic, or overuse injuries. Aim of this study: The aims of this case report are to report a rare clinical complication of glenohumeral joint anterior dislocation that resulted in a patient experiencing continuous GHJ dislocations secondary to involuntary violent muscular spasms and emphasize the role of the physical therapist's differential diagnosis and clinical decision-making process in a patient following direct access referral. Case presentation: A professional 23-year-old cyclist presented to a physical therapist with spontaneous multidirectional dislocations to the right shoulder after the recurrence of trauma occurred during a recent cycling race. The dislocations do not occur at night, but occur during the day, randomly, and mostly associated with changes in the patient's psychological conditions. Directly from the clinical history, the physical therapist identified a neuro-physiological orange flag as well as an orthopedic red flag and, therefore, decided it was appropriate to refer the patient to a neurologist. It was determined by the physical therapist to be a priority to focus on the patient's neurologic status and then to evaluate the orthopedic problem. The neurological examination revealed a condition of spontaneous multidirectional dislocation associated with recurrent antero-posterior pain spasms of the shoulder joint. The neurologist prescribed medication. Following the second cycle of medication assumption, the patient was able to continue physiotherapy treatment and was referred to the orthopedic specialist to proceed with shoulder stabilization surgery. Discussion and conclusion: Currently, the diagnosis of this unusual clinical condition is still unclear. It is a shared opinion of the authors that the trauma during the past bicycle race awakened an underlying psychological problem of the patient that resulted in a clinical condition of weakness of all the structures of the shoulder, such that these spasms could result in multiple multidirectional dislocations.

Nanohertz frequency determination for the gravity probe B high frequency superconducting quantum interference device signal

In this paper, we present a method to measure the frequency and the frequency change rate of a digital signal. This method consists of three consecutive algorithms: frequency interpolation, phase differencing, and a third algorithm specifically designed and tested by the authors. The succession of these three algorithms allowed a 5 parts in 10(10) resolution in frequency determination. The algorithm developed by the authors can be applied to a sampled scalar signal such that a model linking the harmonics of its main frequency to the underlying physical phenomenon is available. This method was developed in the framework of the gravity probe B (GP-B) mission. It was applied to the high frequency (HF) component of GP-B's superconducting quantum interference device signal, whose main frequency f(z) is close to the spin frequency of the gyroscopes used in the experiment. A 30 nHz resolution in signal frequency and a 0.1 pHz/s resolution in its decay rate were achieved out of a succession of 1.86 s-long stretches of signal sampled at 2200 Hz. This paper describes the underlying theory of the frequency measurement method as well as its application to GP-B's HF science signal.

Development of a new CBR-based platform for human contamination emergency situations

In the case of a radiological emergency situation, involving accidental human exposure, it is necessary to establish as soon as possible a dosimetry evaluation. In most cases, this evaluation is based on numerical representations and models of the victims. Unfortunately, personalised and realistic human representations are often unavailable for the exposed subjects. Hence, existing models like the 'Reference Man' representative of the average male individual are used. However, the accuracy of the treatment depends on the similarity of the phantom to the victim. The EquiVox platform (Research of Equivalent Voxel phantom) developed in this work uses the case-based reasoning principles to retrieve, from a set of existing phantoms, the most adapted one to represent the victim. This paper introduces the EquiVox platform and gives the example of in vivo lung monitoring optimisation to prove its efficiency in choosing the right model. It also presents the artificial neural network tools being developed to adapt the model to the victim.

[Simulation of lung motions using an artificial neural network]

PURPOSE

A way to improve the accuracy of lung radiotherapy for a patient is to get a better understanding of its lung motion. Indeed, thanks to this knowledge it becomes possible to follow the displacements of the clinical target volume (CTV) induced by the lung breathing. This paper presents a feasibility study of an original method to simulate the positions of points in patient's lung at all breathing phases.

PATIENTS AND METHODS

This method, based on an artificial neural network, allowed learning the lung motion on real cases and then to simulate it for new patients for which only the beginning and the end breathing data are known. The neural network learning set is made up of more than 600 points. These points, shared out on three patients and gathered on a specific lung area, were plotted by a MD.

RESULTS

The first results are promising: an average accuracy of 1mm is obtained for a spatial resolution of 1 × 1 × 2.5mm(3).

CONCLUSION

We have demonstrated that it is possible to simulate lung motion with accuracy using an artificial neural network. As future work we plan to improve the accuracy of our method with the addition of new patient data and a coverage of the whole lungs.

[Clarity and legal authority in decisions to limit therapy]

The decision to limit a patient's therapy can lead to conflicts in the therapeutic team if their views have not been carefully weighed. Further problems also result if they are not clearly and logically documented. The legal authority of patient will, medical indication, and interaction of the care-giving team for arriving at a common decision are examined here. Using a case history as an example, we discuss ethical and legal questions of documentation and obligations on those faced with concrete decisions whether to continue medical procedures. To widen the basis for such decisions, discussion must include the viewpoints of all participants. The final decision must then be clearly documented without any unclarity or ambivalence. Those finally required to carry out that prospective decision, however, must decide whether it actually applies to the situation at hand.

The role of venography in the evaluation of malfunctioning central venous access ports (CVAPs)

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Background: Malfunction of CVAPs is common in cancer patients receiving chemotherapy. We evaluated the role of venography as a means of assessing the cause of malfunction. Methods: We reviewed and analyzed data available from cancer patients who had a venogram for a malfunctioning CVAP between 1/03 to 3/05. All patients in our institution who have a malfunctioning CVAP receive a trial of intracatheter thrombolytics. If the malfunction persists, then a venogram is performed through the catheter. Results: Seventy-seven patients were studied. The indication for evaluation was inability to aspirate blood (54%), pain (18%), swelling at site of injection (10%), difficult aspiration and infusion (6.5%) and others (11.5%). Forty-four patients had chest ports (31% left and 26% right side), while 33 patients had the CVAP placed in the upper extremity (24% right and 18% left arm). Fibrin sheath or thrombus was the most common finding in 44% of patients, and 41% of venograms were normal. Only two patients had soft tissue extravasation of contrast. Sites of extravasation were in the chest at the catheter/port junction and in the supraclavicular area secondary to a catheter fracture. In patients with aspiration failure, 68% had either a fibrin sheath or thrombus at the catheter tip, 14% had CVAP malposition as the only abnormality, 14% were normal and one patient had extravasation. The CVAP tips were optimally positioned in 70% of patients (distal superior vena cava (SVC), venocava-atrial junction or atrium), while 30% were in a suboptimal position (proximal SVC, brachiocephalic, azygous, or internal jugular vein). Suboptimally positioned CVAPs had a higher incidence of an associated abnormality compared to optimally positioned CVAPs (58% vs. 4% P = 0.001). Only five CVAPs were removed, for extravasation (1), cellulitis (2), and malposition (2). Conclusion: Although the incidence of extravasation was low, venography evaluation could be considered in patients with malfunctioning catheters receiving a vesicant drug to help prevent a potentially significant complication. CVAPs with suboptimally positioned tips had a higher rate of associated abnormalities, emphasizing the importance of proper tip position.

No significant financial relationships to disclose.

Citrate synthase and pyruvate kinase activities during early life stages of the shrimp Farfantepenaeus paulensis (Crustacea, Decapoda, Penaeidae): effects of development and temperature

Energy metabolism in early life stages of the shrimp Farfantepenaeus paulensis subjected to temperature reduction (26 and 20 degrees C) was determined using the activities of citrate synthase (CS) and pyruvate kinase (PK). At both temperatures, weight-specific activity of CS decreased throughout the ontogenetic development from protozoea II (PZ II) to postlarva XII-XIV (PL XII-XIV). PK activity reached a pronounced peak in PL V-VI, followed by a further decrease in PL XII-XIV. Temperature reduction produced variation in oxygen consumption rates (QO(2)), ammonia-N excretion and in enzyme activities. Ammonia-N excretion was higher at 20 degrees C in mysis III (M III), PL V-VI and PL XII-XIV, resulting in substantially lower O:N ratios in these stages. QO(2) was increased in protozoea II (PZ II) and mysis I (M I) at 26 degrees C, while no difference in QO(2) was detected in the subsequent stages at either temperature. This fact coincided with higher CS and PK activities in M III, PL V-VI and PL XII-XIV at 20 degrees C compared with 26 degrees C. Regressions between individual enzyme activities and dry weight exhibited slope values of 0.85-0.92 for CS and 1.1-1.2 for PK and temperature reduction was reflected by higher slope values at 20 than at 26 degrees C for both enzymes. Weight-specific CS activity was positively correlated with QO(2) at 20 and 26 degrees C, and may thus be used as an indicator of aerobic metabolic rate throughout the early stages of F. paulensis. The variation in enzyme activities is discussed in relation to possible metabolic adaptations during specific ontogenetic events of the F. paulensis life cycle. Here, the catalytic efficiency of energy-metabolism enzymes was reflected in ontogenetic shifts in behaviour such as larval settlement and the adoption of a benthic existence in early postlarvae. In most cases, enhanced enzyme activities appeared to counteract negative effects of reduced temperature.

Lipid composition of outer leaflet of chloroplast outer envelope determines topology of OEP7

OEP7, a 6.7-kDa outer envelope protein of spinach chloroplasts inserts into the outer envelope of the organelle independent of a classical cleavable targeting signal. The insertion of OEP7 was studied to describe the determinants for association with, integration into, and orientation of the protein in the outer envelope of chloroplasts. The insertion of OEP7 into the membrane is independent of outer membrane channel proteins and can be reconstituted with the use of protein-free liposomes. In situ, the binding of OEP7 to the membrane surface is not driven by electrostatic interaction because reduction of phosphatidylglycerol or phosphatidylinositol did not reduce the association with the liposomes. The positively charged amino acids flanking the transmembrane domain at the C terminus are essential to retain the native N(in)-C(out) orientation during insertion into chloroplasts. OEP7 inserts with reversed orientation into liposomes containing the average lipid composition of the outer envelopes. The native like N(in)-C(out) orientation is achieved by reduction of the phoshpatidylglycerol concentration mimicking the composition of the outer leaflet of the outer envelope of chloroplasts. We conclude that the unique lipid composition of the outer leaflet due to lipid asymmetry of the outer envelope is essential for the correct topology of OEP7.

Functional and structural similarity of V gamma 9V delta 2 T cells in humans and Aotus monkeys, a primate infection model for Plasmodium falciparum malaria

Gammadelta T cells are implicated to play crucial roles during early immune responses to pathogens. A subset of human gammadelta T cells carrying the Vgamma9Vdelta2 TCR recognize small, phosphorylated nonpeptidic Ags. However, the precise role of these cells and the ligands recognized in human immune responses against pathogens remains unclear because of the lack of suitable animal models. We have analyzed the reactivity of spleen cells of the New World monkey Aotus nancymaae against isopentenyl pyrophosphate (IPP), a phosphorylated microbial metabolite selectively activating Vgamma9Vdelta2 T cells. Spleen cells were stimulated by IPP and the expanding cell population expressed the Vgamma9 TCR. TRGV-J and TRDV-D-J rearrangements expressed by IPP-stimulated cells of Aotus were analyzed by RT-PCR and DNA sequencing. The TRGV-J and TRDV-D-J rearrangements expressed by IPP-stimulated Aotus and human gammadelta T cells were similar with respect to 1) TCR gene segment usage, 2) a high degree of germline sequence homology of the TCR gene segments used, and 3) the diversity of the CDR3 regions. Phylogenetic analysis of human, Pan troglodytes, and A. nancymaae TRGV gene segments showed that the interspecies differences are smaller than the intraspecies differences with TRGV9 gene segments located on a distinct clade of the phylogenetic tree. The structural and functional conservation of Vgamma9Vdelta2 T cells in A. nancymaae and humans implicates a functionally important and evolutionary conserved mechanism of recognition of phosphorylated microbial metabolites.

An optomechanical transducer in the blue light receptor phototropin from Avena sativa

The PHOT1 (NPH1) gene from Avena sativa specifies the blue light receptor for phototropism, phototropin, which comprises two FMN-binding LOV domains and a serine/threonine protein kinase domain. Light exposure is conducive to autophosphorylation of the protein kinase domain. We have reconstituted a recombinant LOV2 domain of A. sativa phototropin with various (13)C/(15)N-labeled isotopomers of the cofactor, FMN. The reconstituted protein samples were analyzed by NMR spectroscopy under dark and light conditions. Blue light irradiation is shown to result in the addition of a thiol group (cysteine 450) to the 4a position of the FMN chromophore. The adduct reverts spontaneously in the dark by elimination. The light-driven flavin adduct formation results in conformational modification, which was diagnosed by (1)H and (31)P NMR spectroscopy. This conformational change is proposed to initiate the transmission of the light signal via conformational modulation of the protein kinase domain conducive to autophosphorylation of NPH1.

Phototropins: a new family of flavin-binding blue light receptors in plants

Phototropin is the designation originally assigned to a recently characterized chromoprotein that serves as a photoreceptor for phototropism. Phototropin is a light-activated autophosphorylating serine/threonine kinase that binds two flavin mononucleotide (FMN) molecules that function as blue light-absorbing chromophores. Each FMN molecule is bound in a rigid binding pocket within specialized PAS (PER-ARNT-SIM superfamily) domains, known as LOV (light, oxygen, or voltage) domains. This article reviews the detailed photobiological and biochemical characterization of the light-activated phosphorylation reaction of phototropin and follows the sequence of events leading to the cloning, sequencing, and characterization of the gene and the subsequent biochemical characterization of its encoded protein. It then considers recent biochemical and photochemical evidence that light activation of phototropin involves the formation of a cysteinyl adduct at the C(4a) position of the FMN chromophores. Adduct formation causes a major conformational change in the chromophores and a possible conformational change in the protein moiety as well. The review concludes with a brief discussion of the evidence for a second phototropin-like protein in Arabidopsis and rice. Possible roles for this photoreceptor are discussed.

Studies on metabolic properties in the Northern Krill, Meganyctiphanes norvegica (Crustacea, euphausiacea): influence of nutrition and season on pyruvate kinase

The specific activity and the kinetic properties of partly purified pyruvate kinase (PK) (EC 2.7.1.40) from the Northern Krill, Meganyctiphanes norvegica, were investigated in relation to varying food resources. In order to evaluate the effect of starvation on the total energy metabolism, the respiration rates of fed and unfed krill were determined. The FPLC-elution profile of PK displayed two distinct peaks - PK I and II. The first isoform represented 80% of the total PK activity in the organism, and 20% was contributed by the second isoform. PK I was inhibited by ATP but was not influenced by fructose-1,6-bisphosphate (FBP). In contrast, PK II showed ATP inhibition and up to 2.5-fold increased activity by addition of 17 micromol.l(-1) FBP. The Michaelis-Menten constants of both isoforms were 2-10-fold higher for ADP than for phosphoenolpyruvate (PEP). Alanine showed no regulatory effect on PK I and II. In specimens starved for 7 days oxygen consumption decreased by 20%. Neither the feeding experiments nor the animals captured in the field during low and high productive seasons indicate that PK properties of M. norvegica are modified in relation to food supply. Accordingly, alternative mechanisms are involved in the depression of the metabolic rate in terms of oxygen consumption.

Photochemical and mutational analysis of the FMN-binding domains of the plant blue light receptor, phototropin

The plant photoreceptor phototropin is an autophosphorylating serine-threonine protein kinase activated by UV-A/blue light. Two domains, LOV1 and LOV2, members of the PAS domain superfamily, mediate light sensing by phototropin. Heterologous expression studies have shown that both domains function as FMN-binding sites. Although three plant blue light photoreceptors, cry1, cry2, and phototropin, have been identified to date, the photochemical reactions underlying photoactivation of these light sensors have not been described so far. Herein, we demonstrate that the LOV domains of Avena sativa phototropin undergo a self-contained photocycle characterized by a loss of blue light absorbance in response to light and a spontaneous recovery of the blue light-absorbing form in the dark. Rate constants and quantum efficiencies for the photoreactions indicate that LOV1 exhibits a lower photosensitivity than LOV2. The spectral properties of the photoproduct produced for both LOV domains are unrelated to those found for photoreduced flavins and flavoproteins, but are consistent with those of a flavin-cysteinyl adduct. Flavin-thiol adducts are generally short-lifetime reaction intermediates formed during the flavoprotein-catalyzed reduction of protein disulfides. By site-directed mutagenesis, we have identified several amino acid residues within the putative chromophore binding site of LOV1 and LOV2 that appear to be important for FMN binding and/or the photochemical reactivity. Among those is Cys39, which plays an important role in the photochemical reaction of the LOV domains. Replacement of Cys39 with Ala abolished the photochemical reactions of both LOV domains. We therefore propose that light sensing by the phototropin LOV domains occurs via the formation of a stable adduct between the FMN chromophore and Cys39.

Photochemical and mutational analysis of the FMN-binding domains of the plant blue light receptor, phototropin

The plant photoreceptor phototropin is an autophosphorylating serine-threonine protein kinase activated by UV-A/blue light. Two domains, LOV1 and LOV2, members of the PAS domain superfamily, mediate light sensing by phototropin. Heterologous expression studies have shown that both domains function as FMN-binding sites. Although three plant blue light photoreceptors, cry1, cry2, and phototropin, have been identified to date, the photochemical reactions underlying photoactivation of these light sensors have not been described so far. Herein, we demonstrate that the LOV domains of Avena sativa phototropin undergo a self-contained photocycle characterized by a loss of blue light absorbance in response to light and a spontaneous recovery of the blue light-absorbing form in the dark. Rate constants and quantum efficiencies for the photoreactions indicate that LOV1 exhibits a lower photosensitivity than LOV2. The spectral properties of the photoproduct produced for both LOV domains are unrelated to those found for photoreduced flavins and flavoproteins, but are consistent with those of a flavin-cysteinyl adduct. Flavin-thiol adducts are generally short-lifetime reaction intermediates formed during the flavoprotein-catalyzed reduction of protein disulfides. By site-directed mutagenesis, we have identified several amino acid residues within the putative chromophore binding site of LOV1 and LOV2 that appear to be important for FMN binding and/or the photochemical reactivity. Among those is Cys39, which plays an important role in the photochemical reaction of the LOV domains. Replacement of Cys39 with Ala abolished the photochemical reactions of both LOV domains. We therefore propose that light sensing by the phototropin LOV domains occurs via the formation of a stable adduct between the FMN chromophore and Cys39.

Effects of temperature on the respiration rates and the kinetics of citrate synthase in two species of Idotea (Isopoda, Crustacea)

The two species of isopods, Idotea baltica (Pallas) and Idotea emarginata (Fabricius), co-occur frequently near Helgoland, North Sea, occupying different ecological niches. Respiration rates and kinetic properties of citrate synthase (CS) were compared in these species in order to identify possible mechanisms of temperature adaptation. Specimens were acclimated to 5 and 15 degrees C prior to further investigations. Respiration rates were measured under normoxic conditions at 5, 10 and 15 degrees C. CS was partly purified chromatographically and influences of temperature, pH, substrate saturation and ATP-concentration on enzyme activity were examined. In both species, rising temperatures led to linearly increasing oxygen consumption, with estimated Q10 values between 3.2 and 4.2. Only I. baltica showed an effect of short term acclimation: warm adapted animals had always higher respiration rates than cold adapted ones. In I. emarginata, the acclimation temperature had no effect on oxygen consumption. Furthermore, its CS slightly indicates higher affinity to oxaloacetic acid when specimens were adapted to 15 degrees C compared to those maintained at 5 degrees C. Any effect of the experimental temperature on CS in I. baltica was negligible. The results are discussed in view of the different habitats occupied by the species compared.

LOV (light, oxygen, or voltage) domains of the blue-light photoreceptor phototropin (nph1): binding sites for the chromophore flavin mononucleotide

Phototropism, the bending response of plant organs to or away from a directional light source, is one of the best studied blue light responses in plants. Although phototropism has been studied for more than a century, recent advances have improved our understanding of the underlying signaling mechanisms involved. The NPH1 gene of Arabidopsis thaliana encodes a blue light-dependent autophosphorylating protein kinase with the properties of a photoreceptor for phototropism. NPH1 apoprotein noncovalently binds FMN to form the holoprotein nph1. The N-terminal region of the protein contains two LOV (light, oxygen, or voltage) domains that share homology with sensor proteins from a diverse group of organisms. These include the bacterial proteins NIFL and AER, both of which bind FAD, and the phy3 photoreceptor from Adiantium capillus-veneris. The LOV domain has therefore been proposed to reflect a flavin-binding site, regulating nph1 kinase activity in response to blue light-induced redox changes. Herein we demonstrate that the LOV domains of two nph1 proteins and phy3 bind stoichiometric amounts of FMN when expressed in Escherichia coli. The spectral properties of the chromopeptides are similar to the action spectrum for phototropism, implying that the LOV domain binds FMN to function as a light sensor. Thus, our findings support the earlier model that nph1 is a dual-chromophoric flavoprotein photoreceptor regulating phototropic responses in higher plants. We therefore propose the name phototropin to designate the nph1 holoprotein.