Hospital admissions among patients with Comorbid Substance Use disorders: a secondary analysis of predictors from the NavSTAR Trial.

BACKGROUND: Individuals with substance use disorders (SUDs) frequently use acute hospital services. The Navigation Services to Avoid Rehospitalization (NavSTAR) trial found that a patient navigation intervention for hospitalized patients with comorbid SUDs reduced subsequent inpatient admissions compared to treatment-as-usual (TAU). METHODS: This secondary analysis extends previous findings from the NavSTAR trial by examining whether selected patient characteristics independently predicted hospital service utilization and moderated the effect of the NavSTAR intervention. Participants were 400 medical/surgical hospital patients with comorbid SUDs. We analyzed 30- and 90-day inpatient readmissions (one or more readmissions) and cumulative incidence of inpatient admissions through 12 months using multivariable logistic and negative binomial regression, respectively. RESULTS: Consistent with primary findings and controlling for patient factors, NavSTAR participants were less likely than TAU participants to be readmitted within 30 (P = 0.001) and 90 (P = 0.03) days and had fewer total readmissions over 12 months (P = 0.008). Hospitalization in the previous year (P < 0.001) was associated with cumulative readmissions over 12 months, whereas Medicaid insurance (P = 0.03) and index diagnoses of infection (P = 0.001) and injuries, poisonings, or procedural complications (P = 0.004) were associated with fewer readmissions. None of the selected covariates moderated the effect of the NavSTAR intervention. CONCLUSIONS: Previous findings showed that patient navigation could reduce repeat hospital admissions among patients with comorbid SUDs. Several patient factors were independently associated with readmission. Future research should investigate risk factors for hospital readmission among patients with comorbid SUDs to optimize interventions. TRIAL REGISTRATION: NIH ClinicalTrials.gov NCT02599818, Registered November 9, 2015 https://classic. CLINICALTRIALS: gov/ct2/show/NCT02599818 .

Structure of biomimetic casein micelles: Critical tests of the hydrophobic colloid and multivalent-binding models using recombinant deuterated and phosphorylated ß-casein.

Milk contains high concentrations of amyloidogenic casein proteins and is supersaturated with respect to crystalline calcium phosphates such as apatite. Nevertheless, the mammary gland normally remains unmineralized and free of amyloid. Unlike κ-casein, ß- and αS-caseins are highly effective mineral chaperones that prevent ectopic and pathological calcification of the mammary gland. Milk invariably contains a mixture of two to five different caseins that act on each other as molecular chaperones. Instead of forming amyloid fibrils, several thousand caseins and hundreds of nanoclusters of amorphous calcium phosphate combine to form fuzzy complexes called casein micelles. To understand the biological functions of the casein micelle its structure needs to be understood better than at present. The location in micelles of the highly amyloidogenic κ-casein is disputed. In traditional hydrophobic colloid models, it, alone, forms a stabilizing surface coat that also determines the average size of the micelles. In the recent multivalent-binding model, κ-casein is present throughout the micelle, in intimate contact with the other caseins. To discriminate between these models, a range of biomimetic micelles was prepared using a fixed concentration of the mineral chaperone ß-casein and nanoclusters of calcium phosphate, with variable concentrations of κ-casein. A biomimetic micelle was also prepared using a highly deuterated and in vivo phosphorylated recombinant ß-casein with calcium phosphate and unlabelled κ-casein. Neutron and X-ray scattering experiments revealed that κ-casein is distributed throughout the micelle, in quantitative agreement with the multivalent-binding model but contrary to the hydrophobic colloid models.

Hepatitis C in Black Individuals in the US: A Review.

Importance: In the US, the prevalence of hepatitis C virus (HCV) is 1.8% among people who are Black and 0.8% among people who are not Black. Mortality rates due to HCV are 5.01/100 000 among people who are Black and 2.98/100 000 among people who are White. Observations: While people of all races and ethnicities experienced increased rates of incident HCV between 2015 and 2021, Black individuals experienced the largest percentage increase of 0.3 to 1.4/100 000 (367%) compared with 1.8 to 2.7/100 000 among American Indian/Alaska Native (50%), 0.3 to 0.9/100 000 among Hispanic (200%), and 0.9 to 1.6/100 000 among White (78%) populations. Among 47 687 persons diagnosed with HCV in 2019-2020, including 37 877 (79%) covered by Medicaid (7666 Black and 24 374 White individuals), 23.5% of Black people and 23.7% of White people with Medicaid insurance initiated HCV treatment. Strategies to increase HCV screening include electronic health record prompts for universal HCV screening, which increased screening tests from 2052/month to 4169/month in an outpatient setting. Awareness of HCV status can be increased through point-of-care testing in community-based settings, which was associated with increased likelihood of receiving HCV test results compared with referral for testing off-site (69% on-site vs 19% off-site, P < .001). Access to HCV care can be facilitated by patient navigation, in which an individual is assigned to work with a patient to help them access care and treatments; this was associated with greater likelihood of HCV care access (odds ratio, 3.7 [95% CI, 2.9-4.8]) and treatment initiation within 6 months (odds ratio, 3.2 [95% CI, 2.3-4.2]) in a public health system providing health care to individuals regardless of their insurance status or ability to pay compared with usual care. Eliminating Medicaid's HCV treatment restrictions, including removal of a requirement for advanced fibrosis or a specialist prescriber, was associated with increased treatment rates from 2.4 persons per month to 72.3 persons per month in a retrospective study of 10 336 adults with HCV with no significant difference by race (526/1388 [37.8%] for Black vs 2706/8277 [32.6%] for White patients; adjusted odds ratio, 1.02 [95% CI, 0.8-1.3]). Conclusions and Relevance: In the US, the prevalence of HCV is higher in people who are Black than in people who are not Black. Point-of-care HCV tests, patient navigation, electronic health record prompts, and unrestricted access to HCV treatment in community-based settings have potential to increase diagnosis and treatment of HCV and improve outcomes in people who are Black.

Implementing a peer-supported, integrated strategy for substance use disorder care in an outpatient infectious disease clinic is associated with improved patient outcomes.

BACKGROUND: Substance use disorder (SUD) and infectious disease (ID) care integration may lead to improvements in SUD and ID outcomes. We assessed implementation of integrating peer-supported SUD care in an outpatient ID setting. METHODS: In this implementation study, we describe REcovery in Specialty care Through medication and OutREach (RESTORE), a low-threshold SUD program implemented in a Baltimore outpatient ID clinic. Key program components were clinician training and support in SUD care, prescription of SUD treatment medications, and peer-based psychosocial support provided by peer recovery specialists. We assessed clinician adoption of RESTORE and compared patient outcomes from baseline to 6 months. RESULTS: Between January 2019 and January 2022, the number of ID clinicians (N=61) who prescribed buprenorphine increased eightfold from 3 (5%) to 24 (39%). Of 258 ID patients referred to RESTORE, 182 (71%) engaged, 137 consented to study participation. Mean age in the study sample was 52.1 (SD=10.4), 63% were male, 84% were Black/African-American. Among 127 (93%) who completed 6-month follow-up, fewer participants reported illicit/non-prescribed opioid use in the past 30 days at follow-up (32%) compared to baseline (52%; p<0.001). Similar reductions were noted for cocaine use (47% to 34%; p=0.006), emergency department visits (23% to 9%; p=0.002), and inpatient hospitalizations (15% to 7%; p=0.025). CONCLUSION: SUD care integration into an outpatient ID care setting using a peer-supported implementation strategy was adopted by clinicians and improved clinical outcomes for patients. This strategy is a promising approach to treating people with infectious diseases and SUD.

Identification of diverse lipid-binding modes in the groove of zinc α2 glycoprotein reveals its functional versatility.

ZAG is a multifunctional glycoprotein with a class I MHC-like protein fold and an α1-α2 lipid-binding groove. The intrinsic ZAG ligand is unknown. Our previous studies showed that ZAG binds the dansylated C11 fatty acid, DAUDA, differently to the boron dipyrromethane C16 fatty acid, C16 -BODIPY. Here, the molecular basis for this difference was elucidated. Multi-wavelength analytical ultracentrifugation confirmed that DAUDA and C16 -BODIPY individually bind to ZAG and compete for the same binding site. Molecular docking of lipid-binding in the structurally related Cluster of differentiation 1 proteins predicted nine conserved ligand contact residues in ZAG. Twelve mutants were accordingly created by alanine scanning site directed mutagenesis for characterisation. Mutation of Y12 caused ZAG to misfold. Mutation of K147, R157 and A158 abrogated C16 -BODIPY but not DAUDA binding. L69 and T169 increased the fluorescence emission intensity of C16 -BODIPY but not of DAUDA compared to wild-type ZAG and showed that C16 -BODIPY binds close to T169 and L69. Distance measurements of the crystal structure revealed K147 forms a salt bridge with D83. A range of bioactive bulky lipids including phospholipids and sphingolipids displaced DAUDA from the ZAG binding site but unexpectedly did not displace C16 -BODIPY. We conclude that the ZAG α1-α2 groove contains separate but overlapping sites for DAUDA and C16 -BODIPY and is involved in binding to a bulkier and wider repertoire of lipids than previously reported. This work suggested that the in vivo activity of ZAG may be dictated by its lipid ligand.

Synthesis of the Prototypical Cyclopropyl Dipeptide Mimic and Evaluation of Its Turn-Inducing Capability.

The (+) and (-) enantiomers of a new turn-inducing cyclopropyl dipeptide mimic have been synthesized and evaluated. The mimic derives its turn-inducing capabilities solely from the cyclopropyl group and without the conformational biasing that would be provided by side-chain substituents. The mimic and peptide-mimic hybrids prepared from it have been studied using a combination of spectroscopic techniques (NMR, IR, and CD). The dipeptide mimic itself displays intramolecular hydrogen bonding in organic solvents, which differs from that observed in natural peptide turns. In contrast, more elaborate peptide-mimic hybrids exhibit hydrogen bonding characteristics that vary with solvent but are consistent with structures found in the tetrapeptide portion (i → i + 3) of a native ß-turn.

Views of barriers and facilitators to continuing methadone treatment upon release from jail among people receiving patient navigation services.

BACKGROUND: Patient navigation has potential for assisting patients who initiate methadone during pretrial detention to enter and remain in treatment following release, but we know little about participants' experiences with this service. METHODS: This study drew a purposive sample of male and female participants (N = 17) from participants enrolled in a randomized trial of initiating methadone with vs. without patient navigation while in the Baltimore City Detention Center. The study interviewed participants in the community at 1 and 3 months following release and asked them about their experiences of reentry, methadone treatment continuation, drug use, and interactions with the patient navigator. The study recorded, transcribed, coded using Atlas.ti, and analyzed thematically the interviews. RESULTS: Participants reported encountering four key challenges in the community: getting to treatment following release, assembling basic supports, managing criminal justice system demands, and staying in treatment. Participants' experiences of the patient navigator's support to address these challenges fell into six thematic groups: showing nonjudgmental caring and persistence, advocating within programs, brokering resources, managing interactions with the criminal justice system, balancing encouragement and self-determination, and offering genuine and familial-type support. CONCLUSION: Nearly all participants appreciated the navigator's support and deemed it helpful. The previously reported randomized trial found that participants assigned to initiate methadone treatment with navigation had higher rates of receiving their first "guest" methadone dose in the community but did not have significantly different rates of treatment enrollment or of illicit opioid use compared to those assigned to begin methadone treatment without navigation. Treatment programs should work to improve retention and postrelease outcomes among this population.

Randomized trial of methadone treatment of arrestees: 24-month post-release outcomes.

BACKGROUND: We report on the 24-month post-release outcomes of arrestees with opioid use disorder (OUD) enrolled in a randomized trial comparing three treatment approaches initiated in jail. METHODS: Adults (N = 225) receiving medically supervised withdrawal from opioids in the Baltimore Detention Center within a few days of arrest were randomly assigned to: (1) interim methadone treatment plus patient navigation (IM + PN) started in the Detention Center; (2) IM; or (3) Enhanced Treatment-as-Usual (ETAU) consisting of detoxification with methadone and referral to treatment in the community. Participants in both methadone conditions could transfer to standard methadone treatment following release. Participants were interviewed at baseline, and 1, 3, 6, 12, and 24 months post-release. Urine was drug tested at follow-up and official arrest records were obtained. RESULTS: On an intention-to-treat basis, there were no significant differences among the three conditions over the 24-month post-release period in terms of opioid- or cocaine-positive urine test results or self-reported opioid or cocaine use, meeting opioid or cocaine use disorder criteria, self-reported criminal behavior, or the number of official arrests. There were 9 fatal overdoses, none occurring during methadone treatment, and 109 hospitalizations unrelated to the study. CONCLUSIONS: Given the high morbidity and mortality found in this population of arrestees and costs to society associated with their health care utilization and continued crime and arrests, research aimed at finding more effective interventions should be continued. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: NCT02334215.

Cost and cost-effectiveness of interim methadone treatment and patient navigation initiated in jail.

BACKGROUND: Individuals with opioid use disorder (OUD) who are released from pre-trial detention in jail have a high risk of opioid relapse. While several interventions for OUD initiated during incarceration have been studied, few have had an economic evaluation. As part of a three-group randomized trial, we estimated the cost and cost-effectiveness of a negative urine opioid test. Detainees were assigned to interim methadone (IM) in jail with continued methadone treatment post-release with and without 3 months of post-release patient navigation (PN) compared to an enhanced treatment-as-usual group. METHODS: We implemented a micro-costing approach from the provider's perspective to estimate the cost per participant in jail and over the 12 months post-release from jail. Economic data included jail-based and community-based service utilization, self-reported healthcare utilization and justice system involvement, and administrative arrest records. Our outcome measure is the number of participants with a negative opioid urine test at their 12-month follow-up. We calculated incremental cost-effectiveness ratios (ICERs) for intervention costs only and costs from a societal perspective. RESULTS: The average cost of providing patient navigation services per individual beginning in jail and continuing in the community was $283. We find that IM is dominated by ETAU and IM + PN. Per additional participant with a negative opioid urine test, the ICER for IM + PN including intervention costs only is $91 and $305 including societal costs. CONCLUSIONS: IM + PN is almost certainly the cost-effective choice from both an intervention provider and societal perspective.

Impact of methadone treatment initiated in jail on subsequent arrest.

BACKGROUND: There are limited data from randomized trials about the impact of starting methadone treatment in jail on subsequent arrest after release for adults with opioid use disorder (OUD). METHODS: Official arrest records were obtained for 212 participants with OUD who were enrolled in a three-group randomized controlled trial of initiating methadone treatment in jail either with or without patient navigation vs. enhanced treatment-as-usual in Baltimore, Maryland. Participants treated for opioid withdrawal in jail were assigned to: 1) interim methadone (IM) with patient navigation (PN; IM + PN); 2) IM without PN (IM); or 3) enhanced treatment-as-usual (ETAU). Participants in both IM groups were able to continue treatment at a community-based methadone treatment program with counseling upon release, while ETAU participants received overdose information and a city-wide treatment assessment/referral number. Likelihood of arrest, time to first subsequent arrest, and severity of arrest charges in the 12 months following release were examined for: 1) combined IM + PN and IM groups compared to ETAU; and 2) IM + PN compared to IM. RESULTS: Within 12 months of release from the index incarceration, 50.5% of the sample had been arrested. The majority of arrest charges (71%) were for low-level, nonviolent crimes. On an intention-to-treat basis, there were no significant differences between the combined IM + PN and IM groups vs. ETAU or IM + PN vs. IM in the likelihood of arrest, time to first subsequent arrest, or severity of arrest charges. CONCLUSION: Initiating IM with or without PN during pretrial detention did not have a significant effect on subsequent arrest during a 12-month post-release follow-up compared to not starting methadone maintenance during detention, despite the high rate of methadone treatment entry in the community following release. This finding may be attributable to the considerable attrition from treatment in the community or other systematic factors. Additional interventions may be needed to reduce the likelihood of subsequent arrest.

A Latent Class Analysis of HIV Risk Factors Among Men and Women with Opioid Use Disorder in Pre-trial Detention.

Adults entering pre-trial detention who inject drugs are at high risk for acquiring HIV/AIDS. In the current study, we examined pre-incarceration HIV risk behaviors among 114 people with opioid use disorder who inject drugs. Participants were recruited from the Baltimore City Detention Center as part of a randomized controlled trial of pre-release methadone treatment. Using latent class analysis, we found three separate latent classes, which we identified as the sex exchange class (14.2%), drug equipment sharing class (36.8%) and lower risk class (49.0%). Women in the sex exchange class (n = 16) reported having multiple male partners and selling sex for money or drugs; however, this group also reported more consistent condom use and less frequent injection drug and equipment sharing than participants in the drug equipment sharing class. Our findings highlight distinct profiles of jail detainees with OUD based on their risks for HIV, and could inform more targeted interventions for each group.Clinical Trials Registration: Clinicaltrials.gov NCT02334215.

Tunable Supramolecular Gel Properties by Varying Thermal History.

The possibility of using differential pre-heating prior to supramolecular gelation to control the balance between hydrogen-bonding and aromatic stacking interactions in supramolecular gels and obtain consequent systematic regulation of structure and properties is demonstrated. Using a model aromatic peptide amphiphile, Fmoc-tyrosyl-leucine (Fmoc-YL) and a combination of fluorescence, infrared, circular dichroism and NMR spectroscopy, it is shown that the balance of these interactions can be adjusted by temporary exposure to elevated temperatures in the range 313-365 K, followed by supramolecular locking in the gel state by cooling to room temperature. Distinct regimes can be identified regarding the balance between H-bonding and aromatic stacking interactions, with a transition point at 333 K. Consequently, gels can be obtained with customizable properties, including supramolecular chirality and gel stiffness. The differential supramolecular structures also result in changes in proteolytic stability, highlighting the possibility of obtaining a range of supramolecular architectures from a single molecular structure by simply controlling the pre-assembly temperature.

LC-HRMS-Database Screening Metrics for Rapid Prioritization of Samples to Accelerate the Discovery of Structurally New Natural Products.

In order to accelerate the isolation and characterization of structurally new or novel secondary metabolites, it is crucial to develop efficient strategies that prioritize samples with greatest promise early in the workflow so that resources can be utilized in a more efficient and cost-effective manner. We have developed a metrics-based prioritization approach using exact LC-HRMS, which uses data for 24 618 marine natural products held in the PharmaSea database. Each sample was evaluated and allocated a metric score by a software algorithm based on the ratio of new masses over the total (sample novelty), ratio of known masses over the total (chemical novelty), number of peaks above a defined peak area threshold (sample complexity), and peak area (sample diversity). Samples were then ranked and prioritized based on these metric scores. To validate the approach, eight marine sponges and six tunicate samples collected from the Fiji Islands were analyzed, metric scores calculated, and samples targeted for isolation and characterization of new compounds. Structures of new compounds were elucidated by spectroscopic techniques, including 1D and 2D NMR, MS, and MS/MS. Structures were confirmed by computer-assisted structure elucidation methods (CASE) using the ACD/Structure Elucidator Suite.

Disclosure of Adolescent Substance Use in Primary Care: Comparison of Routine Clinical Screening and Anonymous Research Interviews.

PURPOSE: The American Academy of Pediatrics recommends substance use screening in adolescent primary care. Many studies of substance use prevalence and screening tool validation are conducted under research protocols that differ from routine clinical screening in context, consequences, and privacy implications. METHODS: This study is a secondary analysis drawing from two projects focused on adolescent primary care patients, aged 12-17, conducted nearly contemporaneously in a Federally Qualified Health Center system. The first project conducted anonymous research interviews with patients (N = 525), while the other tracked routine clinical screening as part of a larger service implementation project (N = 5,971). Both projects assessed substance use with the CRAFFT screening tool. RESULTS: Rates of substance use disclosure and substance use problems were over three and four times higher, respectively, in the anonymous research interview sample compared to rates found in routine clinical screening (p values < .001). CONCLUSIONS: Routine clinical screening may underestimate substance use among adolescents.

Initiating methadone in jail and in the community: Patient differences and implications of methadone treatment for reducing arrests.

The extent to which patient characteristics differ between individuals entering methadone treatment through community programs and jail-based programs is not known. Such differences could impact the likelihood of relapse and recidivism in these two populations and inform efforts at targeting interventions. We compared treatment-entry characteristics of participants enrolling in methadone treatment in two studies conducted in Baltimore, one conducted in community programs (N = 295) and the other in a jail-based program (N = 225). Controlling for age, race, and gender, individuals starting methadone treatment in jail compared to the community, had more severe drug use and criminal justice profiles. These different characteristics suggest that patients initiating methadone in a jail-based program could have greater likelihood of future arrest compared to patients entering community-based treatment. CLINICAL TRIALS REGISTRATION: Clinicaltrials.gov NCT 02334215 and NCT 01442493.

Pharmacotherapy for opioid addiction in community corrections.

Pharmacotherapy for opioid addiction with methadone, buprenorphine, and naltrexone has proven efficacy in reducing illicit opioid use. These treatments are under-utilized among opioid-addicted individuals on parole, probation, or in drug courts. This paper examines the peer-reviewed literature on the effectiveness of pharmacotherapy for opioid addiction of adults under community-based criminal justice supervision in the US. Compared to general populations, there are relatively few papers addressing the separate impact of pharmacotherapy on individuals under community supervision. Tentative conclusions can be drawn from the extant literature. Reasonable evidence exists that illicit opioid use and self-reported criminal behaviour decline after treatment entry, and that these outcomes are as favourable among individuals under criminal justice supervision as the general treatment population. Surprisingly, there is no conclusive evidence regarding the extent to which pharmacotherapy impacts the likelihood of arrest and incarceration among individuals under supervision. However, given the proven efficacy of these three medications in reducing illicit opioid use and the evidence that, in the general population, methadone and buprenorphine treatment are associated with reduction in overdose mortality, the use of all three pharmacotherapies among patients under criminal justice supervision should be expanded while more data are collected on their impact on arrest and incarceration.

Re-engineering methadone-Cost-effectiveness analysis of a patient-centered approach to methadone treatment.

Methadone maintenance treatment has proven effectiveness in the treatment of opioid use disorder, but significant barriers remain to treatment retention. In a randomized clinical trial, 300 newly-admitted methadone patients were randomly assigned to patient-centered methadone (PCM) v. treatment-as-usual (TAU). In PCM, participants were treated under revised program rules which permitted voluntary attendance at counseling and other changes focused on reducing involuntary discharge, and different staff roles which shifted disciplinary responsibility from the participant's counselor to the supervisor. The study found no significant differences in treatment retention, measures of opioid use, or other patient outcomes. This paper employs an activity-based costing approach to estimate the cost and cost-effectiveness of the two study conditions. We found that service use and costs were similar between PCM and TAU. Specifically, the average cost for PCM patients was $2396 compared to $2292 for standard methadone, while the average length of stay was 2 weeks longer for PCM patients. Incremental cost-effectiveness ratios (ICER) for self-reported heroin use, opioid positive urine screens, and meeting DSM-IV criteria for opioid dependence were mixed, with TAU achieving non-significantly better outcomes at lower treatment episode costs (i.e., economically dominating) for opioid positive urine screens. PCM patients reported slightly more days abstinent from heroin and fewer meet the opioid dependence criteria. While these differences are small and not statistically significant, we can still examine the cost-effectiveness implications. For days, abstinent from heroin, the ICER was $242 for one additional day of abstinence, however, there was notable uncertainty around this estimate. For opioid dependence criteria, the ICER was $1160 for a one-percentage point increase in the probability that a participant no longer met criteria for opioid dependence at follow-up. This economic study finds that patient choice concepts can be introduced into methadone treatment without significant impacts on costs or patient outcomes.

Counseling Staff's Views of Patient-Centered Methadone Treatment: Changing Program Rules and Staff Roles.

Conflicts with methadone program counseling staff and violations of program rules can contribute to patients leaving treatment prematurely. This qualitative study was conducted as part of a larger trial of patient-centered methadone treatment (PCM). In-depth, semi-structured interviews at baseline and 12-month follow-up were conducted with five counselors and three clinical supervisors from the programs participating in the PCM parent study. Data were analyzed using Atlas.ti. Counselors reported that, in some cases, PCM allowed them to focus on building a therapeutic alliance with patients because they were not addressing program rule issues. Some reported using more pro-active, innovative strategies for engaging PCM patients and that counseling sessions tended to include a broader range of individually tailored topics, compared to topics normally addressed in typical treatment sessions. Adjusting to the new counselor role was challenging for some counselors and required a shift in tactics to encourage patients' participation in counseling services. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov NCT 01442493.

Characterisation of a pucBA deletion mutant from Rhodopseudomonas palustris lacking all but the pucBAd genes.

Rhodopseudomonas palustris is a species of purple photosynthetic bacteria that has a multigene family of puc genes that encode the alpha and beta apoproteins, which form the LH2 complexes. A genetic dissection strategy has been adopted in order to try and understand which spectroscopic form of LH2 these different genes produce. This paper presents a characterisation of one of the deletion mutants generated in this program, the pucBAd only mutant. This mutant produces an unusual spectroscopic form of LH2 that only has a single large NIR absorption band at 800 nm. Spectroscopic and pigment analyses on this complex suggest that it has basically a similar overall structure as that of the wild-type HL LH2 complex. The mutant has the unique phenotype where the mutant LH2 complex is only produced when cells are grown at LL. At HL the mutant only produces the LH1-RC core complex.