RHD Group Research Articles

Hemispheric specialization and functional impact of ipsilesional deficits in movement coordination and accuracy

Previous studies have demonstrated that following unilateral stroke, motor impairment occurs both contralateral, as well as ipsilateral, to the lesion. Although ipsilesional impairments can be functionally limiting, they can also provide important insight into the role of the ipsilateral hemisphere in controlling movement and the lateralization of specific motor control mechanisms, given that unilateral arm movements are thought to recruit processes in each hemisphere. The purpose of this study was to examine whether left and right hemisphere damage following stroke produces different ipsilesional deficits, and whether our dynamic dominance model of motor lateralization can predict such deficits. Specifically, the dynamic dominance model attributes control of multijoint dynamics to the left hemisphere, and control of steady-state position to the right hemisphere. Chronic stroke patients with either left or right hemisphere damage (LHD or RHD) used their ipsilesional arm, and the control subjects used either their left or right arm (LHC or RHC), to perform targeted reaching movements in different directions within the workspace ipsilateral to their reaching arm. We found that the LHD group showed deficits in controlling the arm's trajectory due to impaired multijoint coordination, but no deficits in achieving accurate final positions. In contrast, the RHD group showed deficits in final position accuracy but not in the ability to coordinate multiple joints during movement, thereby providing additional evidence for the hemisphere-specific nature of motor deficits. Furthermore, while both the LHD and RHD groups were functionally impaired to the same degree on the Jebsen Hand Function Test (JHFT), our results suggest that the underlying mechanisms for such impairment may be hemisphere-dependent.

The Role Of Du Testing In Scaling Down The Burden Of Rhesus-D Negative Transfusion In Northern Nigeria

The low frequency of RhD negativity in Nigeria coupled with a sub-optimal national blood transfusion service has resulted in scarcity of RhD negative blood in Nigerian blood banks. This study was conducted to determine the frequency of D antigen among RhD negative patients scheduled for transfusion with the aim of scaling down the burden of RhD negative transfusion in northern Nigeria. The RhD groups of 2978 patients that were scheduled for transfusion were determined. Samples that were RhD negative were further tested for the D antigen. A total of 2897 (97.3%) samples were RhD positive while 81 (2.7%) samples were RhD negative. Out of the 81 RhD negative samples, 4 (4.9%) were D positive while the remaining 77 (95.1%) samples were D negative. Therefore, the D test may be used to scale down the burden of RhD negative transfusion by 4.9% in northern Nigeria.

Kell alloimmunization in pregnancy: associated with fetal thrombocytopenia?

Kell haemolytic disease in pregnancies has been suggested to be associated with decreased fetal platelet counts. The aim of this study was to evaluate the incidence and clinical significance of fetal thrombocytopenia in pregnancies complicated by Kell alloimmunization. In this retrospective cohort study, fetal platelet counts were performed in 42 pregnancies with severe Kell alloimmunization prior to the first intrauterine blood transfusion. Platelet counts from 318 first intrauterine transfusions in RhD alloimmunized pregnancies were used as controls. Fetal thrombocytopenia (platelet count < 150 x 10(9)/l) was found in 4/42 (10%) in the Kell group and in 84/318 (26%) in the RhD group. None of the fetuses in the Kell alloimmunized pregnancies, including 15 with severe hydrops, had a clinically significant thrombocytopenia defined as a platelet count < 50 x 10(9)/l. In the RhD alloimmunized pregnancies, 2/230 (1%) of the non-hydropic fetuses and 7/30 (23%) of the severely hydropic fetuses had a clinically significant thrombocytopenia. In contrast to fetuses with severe anaemia and hydrops due to RhD alloimmunization, fetuses with severe anaemia due to Kell alloimmunization are generally not at risk for substantial thrombocytopenia.

A RhD Negative Patient Failed to Produce Detectable Anti-D after Transfusion of 35 Units of RhD Positive Red Blood Cells

In the present day, pretransfusion tests include ABO and RhD grouping, antibody screening, antibody identification, and cross matching. Although error rates for these tests have decreased compared to those in the past, clerical errors still occur. When exposed to RhD positive RBCs, a RhD negative person can produce anti-D that causes a severe hemolytic disease of the fetus and the newborn in addition to hemolytic transfusion reactions. Therefore, administration of RhD positive RBCs to a RhD negative person should be avoided. We experienced a RhD negative patient who had been misidentified as positive and transfused 35 units of RhD positive RBCs eight years ago, but did not have detectable anti-D in present. The red cells of the patient showed no agglutination with the anti-D reagent and a negative result in the standard weak D test. The multiplex PCR with sequence-specific priming revealed that the patient was RhD negative.

RHD 1227AIs an Important Genetic Marker for RhDelIndividuals

Approximately 30% of apparently Rh- Taiwanese people actually were RhD(el), a rare variant of the Rh system that might carry a grossly intact RHD gene. Several studies have indicated that the RhD(el) trait might be generated by multiple molecular mechanisms. In this study, a total of 294 Taiwanese serologically RhD- blood donors were tested for Rh phenotypes and RHD genotypes. Among them, total RHD deletion, partial RHD gene, and RhD(el) were found in 185 (62.9%), 15 (5.1%), and 94 (32.0%), respectively. The 1227A allele and exon 9 of the RHD gene were found in all 94 RhD(el) donors. The Ccee was the most prevalent phenotype in the RhD(el) group (78/94 [83%]), and the ccee phenotype was highly prevalent in the true D- group (87.6%). RHD 1227A can be used as an important and useful genetic marker for RhD(el). It can be detected easily by a simple, rapid, specific sequence primer-polymerase chain reaction method.

Hemispheric asymmetries for kinematic and positional aspects of reaching

Kinematic analyses of reaching have suggested that the left hemisphere is dominant for controlling the open loop component of the movement, which is more dependent on motor programmes; and the right hemisphere is dominant for controlling the closed loop component, which is more dependent on sensory feedback. This open and closed loop hypothesis of hemispheric asymmetry would also predict that advance planning should be dependent on the left hemisphere, and on-line response modification, which defines closed loop processes, should be dependent on the right hemisphere. Using kinematic analyses of reaching in patients with left or right hemisphere damage (LHD or RHD), we examined the ability: (i) to plan reaching movements in advance by examining changes in reaction time (RT) when response amplitude and visual feedback were cued prior to the response; and (ii) to modify the response during implementation when target location changed at the RT. Performance was compared between the stroke groups, using the ipsilesional arm, and age-matched control groups using their right (RNC) or left (LNC) arm. Aiming movements to a target that moved once or twice, with the second step occurring at the RT, were performed with or without visual feedback of hand position. There were no deficits in advance planning in either stroke group, as evidenced by comparable group changes in RT with changes in amplitude and visual feedback. Response modification deficits were seen for the LHD group in secondary velocity only. In addition, LHD produced slower initial peak velocity with prolongation of the deceleration phase and faster secondary peak velocities, and the RHD group produced deficits in final error only. These differences are more consistent with the dynamic dominance hypothesis, which links left hemisphere specialization to movement trajectory control and right hemisphere specialization to position control, rather than to global deficits in open and closed loop processing.

Hemispheric specialisation in processing prosodic structures: Revisited

Background : Research addressing prosodic deficits in brain-damaged populations has concentrated on the specialised capabilities of the right and the left cerebral hemispheres in processing the global characteristics of prosody. This focus has been of interest in that the fundamental frequency (F0), duration and intensity acoustic characteristics within a prosodic structure can convey different linguistic and nonlinguistic information. Much of the research investigating this interesting phenomenon has produced conflicting results. As such, different theories have been proposed in an attempt to provide plausible explanations of the conflicting findings regarding hemispheric specialisation in processing prosodic structures. Aims : The purpose of this study was to examine one of the theories, the functional lateralisation theory, through four experiments that altered the linguistic and nonlinguistic functions across a range of prosodic structures. Methods & Procedures : Three groups of subjects participated in each of the four experiments: (1) eight subjects with LHD, (2) eight subjects with RHD, and (3) eight control subjects. The first experiment addressed the extent to which the processing of lexical stress differences would be lateralised to the left or right hemisphere by requiring listeners to determine the meanings and grammatical assignments of two-syllable words conveyed through stressed or unstressed syllables. In another linguistic condition, the second experiment placed demands on syntactic parsing operations by requiring listeners to parse syntactically ambiguous sentences which were disambiguated through the perception of prosodic boundaries located at syntactic junctures. A third linguistic condition required listeners to determine the categorical assignment of a speaker's intention of making a statement or asking a question conveyed through the prosodic structures. The fourth experiment was designed to determine hemispheric lateralisation in processing nonlinguistic prosodic structures. In this experiment, listeners were required to determine the emotional state of a speaker conveyed through the prosodic structures in sentences that contained semantic information which was either congruent or incongruent with the emotional content of the prosodic structures. Results : When subjects were asked to identify lexical stress differences (Experiment 1), syntactically ambiguous sentences (Experiment 2), and questions and statements (Experiment 3) conveyed through prosody, the LHD group demonstrated a significantly poorer performance than the control and RHD groups. When asked to identify emotions conveyed through prosody (Experiment 4), the RHD group demonstrated a significantly poorer performance than the control and LHD groups. Conclusion : These findings support the functional lateralisation theory that proposes a left hemisphere dominance for processing linguistic prosodic structures and a right hemisphere dominance for processing nonlinguistic prosodic structures.

Frecuencias de grupos sanguíneos e incompatibilidades ABO y RhD, en La Paz, Baja California Sur, México

To determine genic and phenotypic frequencies and predict the risk of incompatibility and maternal alloimmunization in the population of La Paz.This descriptive study evaluated 1809 voluntary blood donors attending in 1998 the Hospital General de Zona of Instituto Mexicano del Seguro Social (Zone General Hospital of the Mexican Institute of Social Security) in La Paz, Baja California Sur, Mexico. Blood donors were typified by tube agglutination. The gene frequencies were estimated assuming equilibrium conditions, and incompatibilities and alloimmunization were statistically assessed with the chi 2 test.Percent frequencies were as follows: blood group O, 58.49%; A, 31.40%; B, 8.40%; AB, 1.71%; RhD, 95.36%; and RhD negative, 4.64%. Genic frequencies were: i, 0.7648; IA, 0.1821; IB, 0.0519; D, 0.7845; and d, 0.2155, respectively. Incompatibilities between couples and mother-child were 0.3023 and 0.1685 for ABO, 0.0442 and 0.0364 for RhD, and 0.0134 and 0.0061 for double incompatibility, respectively. The probability of maternal alloimmunization was estimated at 0.0309.The O and RhD groups were the most common in La Paz, although frequencies were among the lowest in Mexico, contrary to the case of A and RhD negative groups. The probabilities of maternal alloimmunization and of incompatibilities were also high. Ancestral white, black, and indigenous groups admixed in the northwestern part of Mexico; after migrating to Baja California Sur the admixture of the population probably became similar to that of the remainder of the northwestern area.

The United Kingdom National External Quality Assessment Scheme (Blood Transfusion Laboratory Practice): trends in proficiency and practice between 1985 and 2000

Proficiency in blood transfusion laboratory practice has improved over the last 15 years (1985-2000). Error rates for ABO grouping have fallen from 0 x 19 to 0 x 02% (P = 0 x 003). A similar trend is evident for antibody screening, with error rates for false negative antibody screens falling from 3 x 2 to 0 x 5% (P < 0 x 001), and for antibody identification, for sera containing a single alloantibody, with error rates falling from 8 x 8% to 0 x 9% over the last 10 years (P < 0 x 001). Proficiency in serological crossmatching to detect clinically significant non-ABO incompatibilities (other than Kidd), has also improved (P < 0 x 001). However, error rates for RhD grouping have not changed and there has been a recent decline in proficiency in detecting weak ABO incompatibilities and Kidd antibodies with heterozygous cells. Procedures for pretransfusion testing have also been rationalized over this time. The indirect antiglobulin test (IAT) is used in isolation by 73% of laboratories for antibody screening, and 10% rely on the direct room temperature (DRT), immediate spin (IS) crossmatch in the absence (current and/or historical) of clinically significant antibodies. Despite the improvements in error rates that have occurred alongside the rationalizations, there is still evidence of noncompliance with current published BCSH guidelines and manufacturers' instructions.

Differential effects of left and right cerebral vascular accidents on language competency

While language facility was once considered to be the sole province of the "dominant" left hemisphere, clinical and experimental findings suggest the right hemisphere plays an equally important role in many language tasks. To elucidate differential hemispheric language processes, Right Hemisphere Language Battery and Western Aphasia Battery data from left (LHD) and right (RHD) hemisphere cerebral vascular accident (CVA) patients and controls were subjected to multivariate discriminant analysis. The highly significant group differences and overall 95% classification rate obtained confirms the utility of the dependent measures in differential diagnosis. Results suggest CVA patients experience disparate language deficits, with the LHD group experiencing concordant-convergent language deficits and the RHD group displaying discordant-divergent deficits that interfere with the receptive and expressive language skills necessary for successful social discourse.

Derivated fetal haemoglobin as a marker for red cell age in the human fetus reflecting stimulated or impaired red blood cell production.

We have determined whether derivated fetal haemoglobin (dHbF, consisting of glycated and acetylated HbF) can be used as a cell age marker for fetal red blood cells (RBCs). Cord blood was obtained between 19 and 39 weeks of gestation from 28 alloimmunised anaemic fetuses (23 RhD+ and 5 Kell) and from 20 non-anaemic fetuses and newborns (controls). Density gradient centrifugation was applied to 36 samples (20 RhD+, 15 controls and 1 Kell) to obtain fractions of increasing cell age. Blood samples were used for measurements of mean cellular volume (MCV), mean cell haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), pyruvate kinase activity (PK) and derivated fetal haemoglobin (dHbF) by cation-exchange HPLC. Reticulocytes were counted only in the whole blood samples. In all density gradient separated RBC fractions, the values for MCV, MCH and PK activity decreased and those of MCHC and dHbF increased with increasing density (equivalent to increasing cell age). The mean density was lower for RBCs of the anaemic RHD group (1.072+/-0.007 g/ml) than for the non-anaemic controls (1.077+/-0.005 g/ml) (p<0.05) The RBC density of the Kell sensitised fetus did not differ from those of the controls. In the control group, the values of the cell age markers in whole blood changed significantly with the gestational age, showing an increase of mean age of the erythrocyte population. The best linear relationship was found for dHbF (y=6.28+0.17*weeks; r=0.84; p<0.001). In the anaemic RhD+ fetuses, the RBC age markers did not change with gestational age; the dHbF percentages were lower, and the MCV, MCH, PK values and the reticulocyte counts were higher than in the controls (0.05<p<0.001). The dHbF values of the Kell sensitised fetuses were above (p<0.01) and the reticulocyte counts were below normal (p<0.05) for gestational age. For the anaemic fetuses, a significant number of the dHbF values (86%) and of the reticulocyte counts (78%) differed from the values of the controls (p<0.01). The dHbF percentages in RhD+ fetuses showed the best correlation with the Hb deficit, which is a measure for anaemia (r=-0.81, p<0.0001). We conclude that the percentage derivated HbF may indicate whether the RBC production is normal for gestational age. It may in that sense reflect stimulated or impaired erythropoiesis in alloimmunised haemolytic anaemia.

The Effect of Compressed Speech on the Ability of Right-Hemisphere-Damaged Patients to Use Context

The ability of RHD patients to use context under conditions of increased processing demands was examined. Subjects monitored for words in auditorily presented sentences of three context types-normal, semantically anomalous, and random, at three rates of speech —normal, 70% compressed (Experiment 1) and 60% compressed (Experiment 2). Effects of semantics and syntax were found for the RHD and normal groups under the normal rate of speech condition. Using compressed rates of speech, the effect of syntax disappeared, but the effect of semantics remained. Importantly, and contrary to expectations, the RHD group was similar to normals in continuing to demonstrate an effect of semantic context under conditions of increased processing demands. Results are discussed relative to contemporary theories of laterality, based on studies with normals, that suggest that the involvement of the left versus right hemisphere in context use may depend upon the type of contextual information being processed.

Distribution of ABO and Rh-D blood groups among blood donors in a tertiary care centre in South India.

The distribution of ABO and Rh-D blood groups was studied among 150,536 blood donors screened at the Dr John Scudder Memorial Blood Bank, Christian Medical College Hospital, Vellore, over a period of 11 years (April 1988 to March 1999). The most common blood group was found to be group O [58,330 (38.75%)], followed by group B [49,202 (32.69%)], and group A [28,372 (18.85%)]. The least common blood group was AB group [7,930 (5.27%)]. A2 or A2B groups were found in 3.01% and 1.43% of donors, respectively. The prevalence of Rh-D negative group was found in 8,225 (5.47%) donors. Bombay group (H negative non-secretor, genotype hh phenotype Oh) was found in six donors (0.004%). Although the incidence of Rh-D negative group was identical to previously published data from North India, the most common blood group was O group in our study as opposed to B group.

Guidelines for pre‐transfusion compatibility procedures in blood transfusion laboratories

1. INTRODUCTION1.1. Purpose of pre-transfusion guidelines.Technicalerrors and/or inappropriate test systems or administrativeerrors may result in immediate and delayed haemolytictransfusion reactions. The purpose of these guidelines,which replace those previously published (BCSH,1991a), is to define organizational, documentation andtechnical procedures undertaken in hospital or RegionalTransfusion Centre laboratories prior to blood transfu-sion.1.2. Elements in pre-transfusion testing1.2.1. ABO and RhD grouping of the recipient1.2.2. Antibody screen of the recipient, or mother in thecase of neonatal transfusion, which in the event of apositive screen, should be followed by antibody identi-fication.1.2.3. A computer or manual check of records. Thesethree elements constitute a group and screen.1.2.4. Donor red cell selection and crossmatching.1.2.5. In certain emergencies, the recipient’s need forimmediate red cell support may dictate that pre-transfu-sion testing is abbreviated.1.3. Clinical significance of red cell antibodies1.3.1. Clinically significant antibodies are those whichare capable of giving rise to accelerated destruction ofred cells bearing the relevant antigen.1.3.2. Anti-A, anti-B and anti-A,B must always beregarded to be of clinical significance.1.3.3. With few exceptions, irregular antibodies whichare potentially clinically significant are only those whichare reactive in the indirect antiglobulin test (IAT),performed strictly at 37

Figures of speech and context awareness following right hemisphere infarcts

The ability to interpret figures of speech was tested in nineteen patients with right hemisphere damage (RDH) and in seventeen controls. All subjects were presented fifteen expressions with metaphoric meanings and asked to select one of three pictures; one illustrating the literal meaning of the expression, one the metaphoric meaning and one a noun in the expression. RHD patients were expected to have problems in interpreting the metaphoric expressions but the hypothesis that the RHD group would select the literal picture more often than the controls was rejected. The groups differed, however, in the distribution of non-metaphoric answers, and in the way the tasks were solved. The performance by the RHD patients may reflect deficient awareness of the context.

Production and Evaluation of Requests by Right Hemisphere Brain-Damaged Individuals

Several researchers have investigated the comprehension of "indirect requests" by fight hemisphere brain-damaged (RHD) individuals. Until the present, however, no sound description of the phenomenon under investigation has been reached and explanatory attempts of the observed behavior are diverse. Based on a theoretical framework issued from studies in cross-cultural pragmatics, the present study is an attempt to provide a systematic description of the production of request sequences and the evaluation of direct and nonconventionally indirect requests by RHD patients. The analyses of the production data showed that, relative to the control group, the RHD patients behaved differently concerning the application of nonconventionally indirect requests, the use of external request modifiers, the evaluation of nonconventionally indirect requests, and the use of propositions. No differences in production performance were observed with regard to direct requests, conventionally indirect requests, and internal request modifiers. Further, the RHD group and the control group behaved similarly in evaluating direct requests. The results are discussed in relation to previous findings and a mental model approach is proposed as an explanatory framework. The findings suggest that the RHD patients were able to build a mental representation at a text level and a situational level but may have had problems within the realm of monitoring or planning integration processes if more than one mental model is involved. There is some indication that attention and visuospatial abilities may have influenced the verbal and evaluation abilities of the RHD subjects. It seems a worthy endeavor to pursue this issue in future research.

DIFFERENTIAL IMPACT OF RIGHT AND LEFT HEMISPHERE LESIONS ON FACIAL EMOTION AND OBJECT IMAGERY

Thirty-six patients with unilateral hemispheric lesions of the right hemisphere (RHD), left hemisphere (LHD), or no neurologic disease were evaluated on two tasks of visual imagery: one involved imagery for facial emotions and the other involved imagery for common objects. As a group, the RHD patients were more impaired on the emotional than the object imagery task, whereas the LHD patients showed the opposite pattern. Individual case analyses suggested that the RHD group consisted of different behavioural subtypes. One patient with a right inferior occipito-temporal lesion had a facial emotion imagery generation defect, other RHD patients displayed a facial affect agnosia (being impaired on emotional imagery and emotional perceptual tasks), while other RHD patients had perceptual defects with sparing of imagery performance. A final RHD group was globally impaired across all imagery and perceptual tasks. These findings support the hypothesis that the right hemisphere may contain a 'lexicon' of facial emotions. Furthermore, these findings argue against current views that it is exclusively the left or right hemisphere that mediates visual imagery. Rather, hemispheric asymmetries in imagery performance are to some extent material-representation specific and may arise when (a) the representations of objects/events to be imaged are differentially represented in the hemispheres, and/or (b) when the operations acting on these imaged events are differentially lateralized.

Comprehension of affective and nonaffective prosody.

We studied patients with damage of either the right (RHD) or left hemisphere (LHD) and control subjects to determine whether the RHD patients had a global or limited prosodic defect. Compared with LHD patients and controls, RHD subjects had decreased comprehension of emotional prosody. Both LHD and RHD groups had more impaired comprehension of propositional prosody than controls, but the RHD and LHD groups did not differ. The right hemisphere, therefore, seems to be dominant for comprehending emotional prosody but not propositional prosody.

Differential drawing size associated with unilateral brain damage

Size of Greek Cross reproductions was compared using 35 persons having unilateral right (RHD), 35 having unilateral left (LHD) hemisphere damage and 38 non-neurologic controls. With right hand tapping speed statistically controlled, RHD drawings were significantly larger than LHD reproductions. Spatial Relations scores were significantly associated with drawing size in the RHD group only, following adjustment for right hand tapping speed. Aphasia Screening scores were unrelated to drawing size. These data demonstrate that LHD/RHD drawing size differences are independent of any basic motor impairment and that for RHD subjects, drawing size is positively correlated with visuospatial impairment.

Verbal Comprehension in Aphasia: An English Version of Three Italian Tests

An English version of three Italian tests of auditory verbal comprehension in aphasia, using picture-choice, was given to four groups of subjects: two groups had suffered cerebral vascular accidents, one with left hemisphere damage and aphasia (LHD)., the other with right hemisphere damage without aphasia (RHD); a third group had undergone bilateral frontal leucotomies (BFL ); the fourth group had no known brain damage (NDB). Six other tests were also given, including the English Picture Vocabulary Test 3 and Raven's Standard Progressive Matrices. Like the Italian test, the English Syntax Test distinguished the aphasic from all the non-aphasic groups; so did the Phonological Test, but only at a confidence level of p < .05 in distinguishing between LHD and RHD. The English Semantic Test, however, did not discriminate between the LHD and the RHD groups. The RHD group performance was significantly different from that of the NBD on the vocabulary test, the Semantic Test and the Matrices. The BFL group showed no significant impairment at the p < .01 confidence level. A comparison of types of errors on the Syntax Test made by the LHD, the RHD and by 4 – 6 year old children suggested a qualitative difference in aphasic breakdown: some aphasics seemed to. have disproportionate difficulties with sentences in which the sequencing of the words was critical to their interpretation.